Cooling the reaction mixture before adding water helps to prevent premature precipitation of the product and ensures better control of the precipitation process, yielding a higher-purity product.
To avoid early or uncontrolled precipitation, which can result in reduced product purity, the reaction mixture is frequently cooled before water is added to precipitate the product. As a result of the product's reduced solubility in the solvent and slowed molecular mobility, cooling increases the likelihood that it may precipitate.
Additionally, cooling might lessen adverse effects that could happen at higher temperatures. In many chemical processes, it enables greater control of the precipitation process, resulting in a larger yield and a purer product.
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what volume of 0.855 mkoh solution do you need to make 3.71 l of a solution with a ph of 11.900? express your answer to three significant figures and include the appropriate units.
The volume of 0.855 M solution needed to make a 3.71 L solution with a pH of 11.900 is 0.0235 L, or 23.5 mL.
To solve this problem, we need to use the Henderson-Hasselbalch equation, which relates the pH of a solution to the pKa and the ratio of the concentrations of the conjugate acid and base. The equation is;
pH = pKa + log([A⁻]/[HA])
where A- is the conjugate base, HA is the acid, and pKa is the dissociation constant of the acid. In this case, we can assume that the acid is water, and the conjugate base is hydroxide (OH⁻).
The pKa of water is 14, so the pKb of hydroxide is 14 - pKa = 14 - 7 = 7. The ratio [A⁻]/[HA] can be calculated from the pH using the equation;
[A⁻]/[HA] = [tex]10^{(pH-pKa)}[/tex]
Substituting the values given in the problem, we have;
[A⁻]/[HA] = [tex]10^{(11.900-7)}[/tex] = 10000
This means that the concentration of hydroxide is 10000 times higher than the concentration of water in the solution. To calculate the volume of the 0.855 M solution needed, we can use the equation;
M₁V₁ = M₂V₂
where M₁ will be the initial concentration, V₁ will be the initial volume, M₂ is final concentration, and V₂ will be the final volume.
Rearranging the equation, we get;
V₁ = (M₂V₂)/M₁
Substituting the values, we get;
V₁ = (0.855 M × 3.71 L) / (10000 + 0.855 M)
Solving this equation gives us;
V₁ = 0.0235 L
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Calculate the volume of 1.25M lithium chloride solution that can be made with 13.3g of lithium chloride
Answer:
0.251 L
Explanation:
convert grams of solute to moles of solute using molar mass
13.3 g LiCl / 42.39 g LiCl gives 0.314 moles of LiCl
Molarity = moles / liter
rework this to solve for liters, which is
moles/molarity = liter
0.314 mol/1.25M = 0.251
many reflux procedures involve a required length of time for the reflux to occur. when should you start timing the reflux for the procedure? select one: when the reflux ring stabilizes in the condenser when you turn on the heat under the flask when the reflux ring passes the top of the condenser when the sample is transferred to the flask
You should start timing the reflux for the procedure when the reflux ring stabilizes in the condenser. This indicates that the condenser is maintaining a consistent flow of coolant, and the reaction mixture is being heated and condensed properly.
Option A is correct
Coolant is a substance, usually a liquid or gas, that is used to cool down a system or device by absorbing and dissipating heat. In automotive engines, coolant is used to prevent the engine from overheating by absorbing heat and transferring it away from the engine.
Coolant is typically a mixture of water and ethylene glycol or propylene glycol, along with additives such as corrosion inhibitors, lubricants, and antifreeze agents.
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When preparing 500. ml of a 1.35 m aqueous solution of nacl, what should you do after adding the correct amount of solute to a large beaker?
After adding the correct amount of solute (NaCl) to a large beaker to prepare 500 ml of a 1.35 M aqueous solution of NaCl,
You should follow these steps:
Add some distilled water to the beaker and dissolve the NaCl completely. Use a stirring rod to assist in the dissolution of the NaCl.
Once the NaCl is completely dissolved, add distilled water to the beaker until the volume reaches 500 ml.
Mix the solution thoroughly using a stirring rod or a magnetic stirrer to ensure that the concentration is uniform throughout the solution.
If necessary, adjust the concentration of the solution by adding more NaCl or distilled water, as required.
Transfer the solution to a clean and dry storage container, such as a plastic bottle or a glass flask, and label it with the concentration, date of preparation, and any other relevant information.
It is important to accurately measure the mass of NaCl to be added and use distilled water for the preparation to ensure that the final concentration of the solution is precise.
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Select the correct hybridization for the central atom based on the electron geometry for 13. Match the items in the left column to the appropriate blanks in the sentences on the right. Reset Help A linear electron geometry has spºd hybridization. trigonal planar trigonal pipyramidal sp? sp3 sp3 d2
The correct hybridization for a linear electron geometry is sp, Based on your question, I understand you want to know the correct hybridization for the central atom based on electron geometry.
Here's a brief summary for some common electron geometries and their corresponding hybridizations: 1. Linear electron geometry: The central atom has sp hybridization, 2. Trigonal planar electron geometry: The central atom has sp2 hybridization.(3)Tetrahedral electron geometry: The central atom has sp3 hybridization.
4. Trigonal bipyramidal electron geometry: The central atom has sp3d hybridization.
5. Octahedral electron geometry: The central atom has sp3d2 hybridization. Keep in mind that hybridization occurs when atomic orbitals combine to form new hybrid orbitals, which are used to describe the bonding in molecules. This helps to explain the shape and geometry of the molecules based on the arrangement of electrons around the central atom.
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A mechanism shown below is proposed for bromination of ethylene (C2H4) in the gas phase. 1. Br2(g) ↹ 2 Br(g) fast 2. C2H4(8) + Br(g) → C2H4Br(g) slow 3. C2H4Br(g) + Br(g) → C2H4Br2(g) fast
What rate law is consistent with the proposed mechanism? a. rate = k[C2H4] [Br] b. rate = k[Br2]
c. rate = k[C2H4][Br2]1/2 d. rate = k[C2H4][Br2]2
Under a rate law where [tex]C_2H_4[/tex] and [tex]Br_2[/tex] are both elevated by a factor of two. As a result, choice c is the appropriate response.
The rate law consistent with the proposed mechanism is:
rate = [tex]k[C_2H_4][Br_2]1/2[/tex]
This is because the second step is the rate-determining step, meaning it is the slowest step in the mechanism and limits the overall reaction rate. The rate law for the slow step involves both [tex]C_2H_4Br[/tex] and Br, but since Br is a reactant in the first step, we can substitute [Br] in terms of [tex][Br_2][/tex] using the fast equilibrium step. This results in a rate law with both [tex]C_2H_4[/tex] and [tex]Br_2[/tex] raised to the power of 1/2. Therefore, the correct answer is option c.
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calculate the mass of na2co3 to react with 25 ml of 0.1 m hcl
To calculate the mass of Na2CO3 needed to react with 25 mL of 0.1 M HCl, we will first need to find the moles of HCl, and then use the balanced chemical equation to determine the moles of Na2CO3 required.
Finally, we'll convert moles of Na2CO3 to mass using its molar mass. The balanced chemical equation for the reaction is:
Na2CO3 + 2HCl → 2NaCl + H2O + CO2
1. Calculate moles of HCl:
moles = Molarity × Volume (in liters)
moles = 0.1 M × (25 mL / 1000)
moles = 0.0025 mol HCl
2. Determine moles of Na2CO3 required:
From the balanced equation, 1 mol of Na2CO3 reacts with 2 mol of HCl.
So, moles of Na2CO3 = (0.0025 mol HCl) / 2
moles of Na2CO3 = 0.00125 mol
3. Calculate mass of Na2CO3:
mass = moles × molar mass
molar mass of Na2CO3 = (2 × 22.99) + 12.01 + (3 × 16.00) = 105.99 g/mol
mass = 0.00125 mol × 105.99 g/mol
mass ≈ 0.13 g, So, approximately 0.13 g of Na2CO3 is needed to react with 25 mL of 0.1 M HCl.
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calculate the δg∘rxn using the following information. 2 h2s (g) 3 o2 (g) → 2 so2 (g) 2 h2o (g) δg∘rxn = ? δgf -33.4 -300.1 -228.6
The δg∘rxn (free energy of reaction) for the reaction 2 H₂S (g) + 3 O₂ (g) → 2 SO₂(g) + 2 H₂O (g) is -990.6 kJ/mol
To find the δg∘rxn (free energy of reaction) for the reaction 2 H₂S (g) + 3 O₂ (g) → 2 SO₂ (g) + 2 H₂O (g), you'll need to use the following formula:
δg∘rxn = Σ (δgf products) - Σ (δgf reactants)
where, δgf is the standard Gibbs free energy of formation for each compound involved in the reaction.
The given values for δgf are:
- H₂S: -33.4 kJ/mol
- O₂: 0 kJ/mol (since it's an element in its standard state)
- SO₂: -300.1 kJ/mol
- H₂O: -228.6 kJ/mol
Now, apply the formula:
δg∘rxn = [(2 × -300.1) + (2 × -228.6)] - [(2 × -33.4) + (3 × 0)]
δg∘rxn = (-600.2 - 457.2) - (-66.8)
δg∘rxn = -1057.4 + 66.8
δg∘rxn = -990.6 kJ/mol
So, the δg∘rxn for the given reaction is -990.6 kJ/mol.
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The Navy is considering an osmotic device in their submarines in order to desalinate water when the submarine is submerged. When the submarine is at the appropriate depth, the osmotic device converts seawater into pure water that would be available for use on the submarine. The density of seawater is 1024 kg m–3 and the composition of the seawater is equivalent to a 0.5 M NaCl solution. At what cruising depth would this proposed desalination process work?
The cruising depth at which the proposed desalination process would work is approximately 100 meters.
The osmotic device in the Navy submarines would work at a cruising depth where the pressure is high enough to allow for the process of osmosis to occur. Osmosis is the movement of water molecules from an area of low concentration to an area of high concentration through a semi-permeable membrane. In this case, the membrane would allow water molecules to pass through but not salt molecules.
To determine the cruising depth at which the osmotic device would work, we need to calculate the osmotic pressure of seawater at different depths. The osmotic pressure is the pressure required to prevent the movement of water molecules from a solution through a semi-permeable membrane.
The osmotic pressure of seawater can be calculated using the Van't Hoff equation:
Π = iMRT
where Π is the osmotic pressure, i is the van't Hoff factor (the number of particles the solute dissociates into), M is the molarity of the solution, R is the gas constant, and T is the temperature in Kelvin.
Assuming a temperature of 25°C (298 K), the osmotic pressure of seawater at the surface would be:
Π = 2 x 0.5 M x 0.0821 L atm mol-1 K-1 x 298 K
Π = 24.44 atm
At a depth of 100 meters, the pressure would be approximately 11 atm. Using the same equation, we can calculate the osmotic pressure of seawater at that depth:
Π = 2 x 0.5 M x 0.0821 L atm mol-1 K-1 x 298 K x (11 atm/1 atm)
Π = 268.84 atm
At this pressure, the osmotic device would be able to convert seawater into pure water through osmosis.
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How do i do this chem problem
During the dissolving process, 3,080 J, 146.4 J, and -0.01464 kJ/g of heat are supplied to the water.
Calculation-The formula may be used to determine how much heat is absorbed by water.
Q = m * c * ΔT
where Q represents the heat absorbed, m represents the mass of the water and salt, c represents the heat capacity of the water, and T represents the temperature change.
We are aware that T is 3.50 °C and that the mass of water and salt is 200.0 g + 10.0 g = 210.0 g. When these values are added to the formula, we obtain:
Q=210.0 g*4.184 J/g°C *3.50 °C = 3,080 J
B) The following formula may be used to determine how much heat the salt loses:
Q = m * c * ΔT
where Q is heat loss, m is salt mass, c is water's specific heat capacity, and T is temperature change.
We are aware that the mass of the salt is 10.0 g, and that T is still 3.50 °C. When these values are added to the formula, we obtain:
Q = 10 g * 4.184 J/g°C * 3.50 °C = 146.4 J
C) By dividing the heat lost by the mass of salt and then converting to kilojoules, it is possible to compute the heat lost by the chemicals on a kilojoules per gramme basis:
Heat loss per gramme is equal to (-146.4 J) / (10 g) or -14.64 J/g.
Heat loss per gramme in kJ is calculated as (-14.64 J/g) / 1000 J/kJ = -0.01464 kJ/g.
As a result, the compounds lose -0.01464 kilojoules of heat per gramme of substance.
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Select the common products for a typical combustion reaction of alcohols. a. strong base b. heat c. waterd. carbon dioxide e. inorganic salt
The common products for a typical combustion reaction of alcohols are water, carbon dioxide, and heat. In some cases, inorganic salts may also be formed as products.
Water (H2O) and carbon dioxide (CO2) are the most frequent byproducts of an average combustion reaction of alcohol since they are the end products of the whole oxidation of the alcohol molecule. During combustion, heat is also given off as an exothermic process.
Depending on the particular alcohol and reaction circumstances, inorganic salts may occasionally develop as result. However, as it has no direct connection to the oxidation of alcohols in the presence of oxygen, the creation of a strong base is not a typical byproduct of alcohol combustion.
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although you didn't carry out every test on all eight alcohols, you should be able to predict the results for the tests on the alcohols that you did not test. if your unknown alcohol is one of these eight known alcohols, which do you think yours is? can you definitely identify it? explain your answer using your test results and predicted results.
The statement you mentioned appears to refer to a hypothetical situation where tests were conducted on a subset of alcohols and the results of those tests were used to predict the results for the remaining alcohols.
Without knowing the specific tests conducted, the results obtained, and the characteristics of the alcohols being tested, it would not be possible for me to identify or definitively predict the unknown alcohol. The identification of an unknown alcohol would require a thorough analysis of its properties, characteristics, and test results, and cannot be accurately determined based on incomplete or hypothetical information.
It is important to note that accurate identification of unknown substances, including alcohols, typically requires proper laboratory testing by qualified professionals using appropriate analytical techniques and equipment. Guessing or making assumptions about the identity of an unknown alcohol based on limited information can be unreliable and potentially hazardous. It is always best to rely on qualified experts and proper testing procedures for accurate identification of unknown substances.
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what is the solubility of n2 (mol n2/l solution) in an aqueous solution at a temperature of 37°c?0.015 g/L0.016 g/L0.017 g/L0.018 g/L
The solubility of [tex]N_{2}[/tex] (mol [tex]N_{2}[/tex]/L solution) in an aqueous solution at a temperature of 37°C is approximately 0.015 g/L. Solubility refers to the maximum amount of a solute that can dissolve in a solvent to form a homogeneous solution.
The solubility of a gas in a liquid depends on several factors, including temperature, pressure, and the chemical nature of the gas and liquid. At higher temperatures, the solubility of gases typically decreases, which is known as the "temperature effect." In this case, the temperature is 37°C, which suggests that the solubility of [tex]N_{2}[/tex] in water will be relatively low. Other factors that can affect gas solubility include pressure, the presence of other solutes, and the chemical reactivity of the gas and liquid.
Thus, the solubility of [tex]N_{2}[/tex] (mol [tex]N_{2}[/tex]/L solution) in an aqueous solution at a temperature of 37°C is approximately 0.015 g/L.
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enter your answer in the provided box. calculate δhrxn for ca(s) 1/2 o2(g) co2(g) → caco3(
The enthalpy change (ΔHrxn) for the reaction Ca(s) + 1/2 O2(g) + CO2(g) → CaCO3(s) is -813.4 kJ/mol.
To calculate δhrxn for the reaction:
Ca(s) + 1/2 O2(g) + CO2(g) → CaCO3(s)
We need to first determine the standard enthalpy of formation (ΔHf°) for each of the species involved.
ΔHf° for CaCO3(s) = -1206.9 kJ/mol
ΔHf° for Ca(s) = 0 kJ/mol
ΔHf° for O2(g) = 0 kJ/mol
ΔHf° for CO2(g) = -393.5 kJ/mol
Using Hess's law, we can then calculate the overall enthalpy change for the reaction:
ΔHrxn = ΣnΔHf°(products) - ΣmΔHf°(reactants)
ΔHrxn = [1(-1206.9 kJ/mol)] - [1(0 kJ/mol) + 1/2(0 kJ/mol) + 1(-393.5 kJ/mol)]
ΔHrxn = -1206.9 + 393.5 = -813.4 kJ/mol
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6.32 draw geometric isomers of 3-chloropent-2-ene
Geometric isomers of 3-Chloropent-2-ene are E and Z-type isomers of the compound. The structures of the compound in E and Z configurations are shown in the figures.
The isomers are of two types in this case that are E- type and Z- type. This system is based on different priorities given to different atoms in the compound.
When the higher priority group of both sides of the double bond are on the same side this is known as a Z-type configuration. And when opposite sides have the highest priority group this type of arrangement is known as an E-type configuration.
Z comes from the German word zusammen which means together while E comes from the German word entgegen meaning opposite
The real advantage of the E-Z system is that it works in every case. In contrast, the cis-trans system is not applicable to each case such as the one given in the question.
Since Cl is higher in priority than C in the ethyl group, the compound having -Cl and [tex]CH_3[/tex] on the same side is called Z-type while one having them on different sides is known as E-type.
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The weak acid HA has a Ka of 4.5×10−6. If a 1.4 M solution of the acid is prepared, what is the pH of the solution? The equilibrium expression is:HA(aq)+H2O(l)⇋H3O+(aq)+A−(aq)
The pH of the weak acid HA in a 1.4 M solution is around 2.64.
To find the pH of a 1.4 M solution of the weak acid HA with a Ka of 4.5×10⁻⁶, we can use the given equilibrium expression:
HA(aq) + H2O(l) ⇋ [tex]H_3O^+[/tex](aq) + A−(aq)
Since HA is a weak acid, we'll assume that only a small amount of it will ionize, and we can represent that amount as x:
HA ⇋ [tex]H_3O^+[/tex] + A−
Initial: 1.4 M 0 0
Change: -x +x +x
Equilibrium: 1.4-x M x x
Now, we can plug these equilibrium concentrations into the Ka expression:
Ka =[tex][H3O^+][/tex][tex][A^-][/tex]/[HA]
4.5×10⁻⁶ = (x)(x)/(1.4-x)
Since x is small compared to 1.4, we can approximate and assume that (1.4-x) ≈ 1.4:
4.5×10⁻⁶ = x^2/1.4
Next, we can solve for x:
x^2 = 4.5×10⁻⁶ * 1.4
x ≈ 2.3×10⁻³
Since x represents the [H3O+], we can now calculate the pH:
pH = -log[H3O+]
pH = -log(2.3×10⁻³)
pH ≈ 2.64
So, the pH of the 1.4 M solution of the weak acid HA is approximately 2.64.
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determine the Ka for the acid HA given that the equilibrium concentrations are [HA]=2.35m, [a−]=0.522 M, and [h3o+ ]=0.522m.Your answer should have three significant figures. Provide your answer below: Ka=
Ka for the acid HA is 0.115.
The Ka value is the equilibrium constant for the dissociation of an acid in water. It is a measure of the strength of an acid and is defined as the ratio of the concentrations of the products of the reaction to the concentration of the acid in its undissociated form.
To determine the Ka value for the acid HA, we need to write the chemical equation for the dissociation of HA in water. The equation is as follows:
HA + H2O ⇌ H3O+ + A-
From the equilibrium concentrations given, we can write the expression for the equilibrium constant, Ka, as:
Ka = [H3O+][A-]/[HA]
Substituting the given concentrations into the equation, we get:
Ka = (0.522 M)2 / 2.35 M = 0.115
Therefore, the Ka value for the acid HA is 0.115 with three significant figures.
This Ka value suggests that the acid HA is a weak acid as it has a low dissociation constant. It means that only a small fraction of the acid molecules dissociate into H3O+ and A- ions in water. Hence, the solution of HA would be acidic but not very strong.
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If the solution is 400 ml and solvent is 300ml so what is concentration of solution
Answer:
Explanation:
Explanation:
Solute = solution - solvent
Solute = 400 - 300
Solute = 100ml
Percentage of Solute = volume of Solute / volume of solution
= 25 %
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how calorimetry can be used to make conclusions about the hydrogen bonding network between solvent molecules when the two solvents are mixed together
The use of calorimetry in this context can provide valuable insights into the thermodynamic properties of solvent mixtures and help researchers better understand the complex interactions between different chemical species.
Calorimetry can be used to make conclusions about the hydrogen bonding network between solvent molecules when two solvents are mixed together. This is because calorimetry measures the heat exchange that occurs during a reaction, which can reveal important information about the strength and stability of the hydrogen bonds between solvent molecules. By measuring the heat of mixing when two solvents are combined, scientists can determine whether or not there are strong interactions between the solvent molecules, which can provide insights into the underlying hydrogen bonding network. This information can then be used to draw conclusions about the behavior of the solvents when they are combined, which can be helpful in a variety of research and industrial applications. Ultimately, the use of calorimetry in this context can provide valuable insights into the thermodynamic properties of solvent mixtures and help researchers better understand the complex interactions between different chemical species.
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Calculate the pH after 0.020 mol NaOHNaOH is added to 1.00 L of each of the solutions below.(a) 0.114 M HONH2HONH2 (Kb=1.1×10−8Kb=1.1×10−8)(b) 0.114 M HONH3ClHONH3Cl(c) pure H2OH2O(d) a mixture containing 0.114 M HONH2HONH2 and 0.114 M HONH3Cl
(a) The pH after 0.020 mol NaOH (strong base) is added to 1.00 L of 0.114 M HONH₂, is 6.8.
(b) When 0.020 mol of NaOH is added to 1.00 L of 0.114 M HONH₃Cl, the resulting pH will be 3.99.
(c) When 0.020 mol of NaOH is added to 1.00 L of pure H₂O, the resulting pH will be 12.30.
(d) When 0.020 mol of NaOH is added to 1.00 L of a mixture containing 0.114 M of both HONH₂ and HONH₃Cl, the resulting pH will be 8.63.
(a) HONH₂ is a weak base and NaOH is a strong base. When NaOH is added, it reacts completely with the weak base to form water and the conjugate base ONH₂⁻.
HONH₂ + NaOH → ONH₂⁻ + H₂O
The initial concentration of HONH₂ was 0.114 M, and 0.020 mol of NaOH is added, which is equivalent to 0.020 M. The final concentration of ONH₂⁻ is also 0.020 M.
To find the pH, we need to find the pOH first. The Kb value of HONH₂ is given as 1.1×10⁻⁸.
Kb = [OH⁻][ONH₂⁻]/[HONH₂]
1.1×10⁻⁸ = [OH-][0.020]/[0.114]
[OH⁻] = 6.27×10⁻⁸ M
pOH = -log[OH⁻] = -log(6.27×10⁻⁸ M) = 7.2
pH = 14 - pOH = 6.8
(b) HONH₃Cl is an ammonium salt and NaOH is a strong base. When NaOH is added, it reacts completely with the ammonium cation to form water and the conjugate base NH₂⁻.
HONH₃Cl + NaOH → NH₂⁻ + H₂O + NaCl
The initial concentration of HONH₃Cl was 0.114 M, and 0.020 mol of NaOH is added, which is equivalent to 0.020 M. The final concentration of NH₂⁻ is also 0.020 M.
To find the pH, we need to find the pOH first. The Kb value of NH₃ is given as 1.8×10⁻⁵, and we need to use the Kw value to account for the H⁺ ion from water.
Kw = [H⁺][OH⁻] = 1.0×10⁻¹⁴
Kb = [NH₂⁻][H⁺]/[NH₃]
1.8×10⁻⁵ = [0.020][H⁺]/[0.114]
[H⁺] = 1.02×10⁻⁴ M
[OH⁻] = Kw/[H⁺] = 9.7×10⁻¹¹ M
pOH = -log[OH⁻] = -log(9.7×10⁻¹¹) = 10.01
pH = 14 - pOH = 3.99
(c) Pure H₂O is neutral with a pH of 7. Adding NaOH to pure water will increase the OH⁻ concentration and decrease the H⁺ concentration, resulting in a higher pH.
The initial concentration of H⁺ and OH⁻ is 1.0×10⁻⁷ M. The addition of 0.020 mol of NaOH is equivalent to 0.020 M.
[OH⁻] = 0.020 M
[H⁺] = Kw/[OH⁻] = 5.0×10⁻¹³ M
pH = -log[H⁺] = -log(5.0×10⁻¹³) = 12.30
(d) This is a buffer solution containing both HONH₂ and HONH₃Cl. The buffer capacity will resist changes in pH upon addition of a small amount of strong acid or base.
When NaOH is added, it will react with both HONH₂ and HONH₃Cl to form the conjugate bases ONH₂⁻ and NH₂⁻.
HONH2 + NaOH → ONH₂⁻ + H2O
HONH3Cl + NaOH → NH₂⁻ + H2O + NaCl
The initial concentration of each weak base was 0.114 M, and 0.020 mol of NaOH is added, which is equivalent to 0.020 M. The final concentration of ONH₂⁻ and NH₂⁻ will be 0.114 - 0.020 = 0.094 M.
To find the pH, we need to calculate the buffer capacity and determine which acid or base is present in excess.
pKa = -log(Ka) = -log(1.1×10⁻⁸) = 7.96
pH = pKa + log([A⁻]/[HA])
For the HONH₂/ONH₂⁻ buffer:
[HA] = 0.020 M (initial concentration of NaOH)
[A-] = 0.094 M (final concentration of ONH₂⁻)
pH = 7.96 + log(0.094/0.020) = 8.63
For the HONH₃Cl/NH₂⁻ buffer:
[HA] = 0.114 M (initial concentration of HONH₃Cl)
[A-] = 0.094 M (final concentration of NH₂⁻
pH = 7.96 + log(0.094/0.114) = 7.87
Since the pH of the HONH₂/ONH₂⁻ buffer is higher than the pH of the HONH₃Cl/NH₂⁻ buffer, it is in excess and will determine the final pH.
Therefore the pH = 8.63.
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Ethanol cannot be added to the test tube too quickly because it will break up the dna precipitate.a. Trueb. False
The statement that ethanol cannot be added to the test tube too quickly because it will break up the DNA precipitate is true. Ethanol is commonly used in DNA extraction protocols to precipitate DNA from solution.
When added slowly, the ethanol gradually changes the conditions in the test tube, causing the DNA to come out of solution and form a visible clump. However, if too much ethanol is added too quickly, it can cause the DNA to break apart and become less visible or even invisible. This is because the high concentration of ethanol can disrupt the hydrogen bonds that hold the DNA strands together, causing them to unravel and lose their structure. Therefore, it is important to add ethanol slowly and carefully to avoid breaking up the DNA precipitate.
In summary, it is important to use the appropriate volume of ethanol based on the volume of the DNA solution, as too much or too little ethanol can also affect the precipitation of the DNA.
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A titration is performed with a 25.00 ml analyte saturated solution of manganese (11) hydroxide with methyl orange indicator, titrated with 0.0045 M HCI. The end point was reached after 8.72 mL of HCI was added. a. What is the molar concentration of OH-in the saturated solution? b. Calculate Ksp for the manganese hydroxide. (Eq.2) c. What is the molar solubility of the manganese hydroxide?
The molar solubility of manganese hydroxide is 0.00157 M.
a. To find the molar concentration of OH- in the saturated solution, we need to first determine the moles of HCl used in the titration:
moles HCl = Molarity x Volume (in L)
moles HCl = 0.0045 M x 0.00872 L
moles HCl = 3.93 x 10^-5 mol
Since Mn(OH)2 reacts with 2 moles of HCl for every 1 mole of Mn(OH)2, we can calculate the moles of Mn(OH)2 in the saturated solution:
moles Mn(OH)2 = 0.5 x moles HCl
moles Mn(OH)2 = 0.5 x 3.93 x 10^-5 mol
moles Mn(OH)2 = 1.97 x 10^-5 mol
Now we can calculate the molar concentration of OH-:
Molarity of OH- = moles OH- / Volume (in L)
Molarity of OH- = 1.97 x 10^-5 mol / 0.025 L
Molarity of OH- = 0.000788 M
b. The balanced equation for the dissolution of manganese hydroxide is:
Mn(OH)2 (s) ⇌ Mn2+ (aq) + 2OH- (aq)
The Ksp expression for this reaction is:
Ksp = [Mn2+][OH-]^2
At the saturation point, the concentration of Mn2+ is equal to the solubility product, so we can use the molar concentration of OH- found in part a to calculate Ksp:
Ksp = [Mn2+][OH-]^2
Ksp = (0.000788 M)(2 x 0.000788 M)^2
Ksp = 2.48 x 10^-8
Therefore, the Ksp for manganese hydroxide is 2.48 x 10^-8.
c. The molar solubility of manganese hydroxide is the molar concentration of Mn(OH)2 in a saturated solution. From part b, we know the solubility product of manganese hydroxide, so we can use that value to find the molar solubility:
Ksp = [Mn2+][OH-]^2
2.48 x 10^-8 = x(2x)^2
x = 0.00157 M
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Please help with these 3 questions for chemistry DUE TOMORROW!
The equilibrium concentration of Ammonia is 0.79 M at the specified temperature.
4 moles of hydrogen and 2 moles of oxygen react to form how many moles of water?There are no limiting reagents because the reactants are present in stoichiometric ratios. A. The reaction between 4 moles of Hydrogen and 2 moles of Oxygen results in the formation of 4 moles of water.
H(g) + I(g) ⇌ 2HI(g)
Keq = [HI]² / [H][I]
At equilibrium, the concentrations are:
[H] = 4 moles / 1 L = 4 M
[I] = 4 moles / 1 L = 4 M
[HI] = 1 mole / 1 L = 1 M
These values are entered into the expression for Keq and result in: Keq = (1)² / (4)(4) = 0.0625
Therefore, at 250°C, the equilibrium constant for the reaction H(g) + I2(g) ⇌ 2HI(g) is 0.0625.
The balanced chemical equation for the reaction is:
N(g) + 2O(g) ⇌ 2NO(g)
Keq = [NO]² / [N][O]²
Substituting these values into the expression for Keq gives:
42 = (1.5)² / (1)([O]²)
Solving for [O] gives:
[O] = √(1.5² / 42) = 0.128 M
Therefore, at the given temperature, the equilibrium concentration of Nitrogen mono oxide is 1.5 M and the equilibrium concentration of Oxygen is 0.128 M.
3H(g) + N(g) ⇌ 2NH₃(g)
Keq = [NH₃]² / [H]³[N]
At equilibrium, the concentrations are:
[H] = 0.40 M
[N] = 0.25 M
[NH₃] = ? (to be calculated)
20 = [NH₃]² / (0.40)³(0.25)
Solving for [NH₃] gives:
[NH₃] = √(20 × (0.40)³ × (0.25)) = 0.79 M
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which activity is most likely to be fueled primarily by lactic acids? group of answer choices 400-meter run 5-mile run a tennis serve 2 hour hike 100-meter run
The activity that is most likely to be fueled primarily by lactic acid is the 400-meter run.
Lactic acid is produced in the body when there is not enough oxygen available to produce energy aerobically, which is the case during high-intensity exercises such as sprinting. The 400-meter run is a middle-distance sprint that requires a high level of anaerobic energy production.
This means that the body relies more on lactic acid to fuel the muscles during the race. On the other hand, the 5-mile run, 2-hour hike, and tennis serve are all endurance activities that rely more on aerobic energy production, which uses oxygen to produce energy. These activities do not require as much lactic acid production as the 400-meter run because they are less intense and require longer periods of sustained energy.
The 100-meter run, while still a sprint, is shorter and less intense than the 400-meter run, so it also relies less on lactic acid as a fuel source.
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Molar Ratio Practice Problems Following each equation are two requests for molar ratios from the equation 1) NH 3 HINH Na to Ha NH, to H: 2)2 SO, +-. 2 SO O to SO, O to SO, 3) PCB + Cl - PCI PCI to CI: PCI to PCI: 4} + NH3 + 3 0 - 2 N2 + 6 HỆ NH 10 N2 H2O to 2: 5) Fe2O + 3 CO-2 Fe + 3 CO2 со tо со Fe to CO: Mole to Mole Practice Problems Here's the equation to use for all three problems: 2 H2 + O2 + 2H2O 1) How many moles of H20 are produced when 5 moles of oxygen are used? Remember: Starting with five moles of oxygen and based on the balanced equation, for every / mole of oxygen used, two moles of water are produced moles O2 x 2 mole H2O moles H2O 1 mole 0 2) If 3.00 moles of H:0 are produced, how many moles of oxygen must be consumed? 3) If 2.5 moles of H.O are produced, how many moles of hydrogen gas must be used.? 4) Suppose 4.00 grams of H2 were used? How many grams of water would be produced?
1)5 moles O2 x 2 moles H2O / 1 mole O2 = 10 moles H2O
10 moles H2O
Based on the balanced equation, for every 1 mole of oxygen used, 2 moles of water are produced. Therefore, 5 moles of oxygen would produce 10 moles of water.
2)3.00 moles H2O x 1 mole O2 / 2 moles H2O = 1.50 moles O2
1.50 moles O2
Based on the balanced equation, for every 2 moles of water produced, 1 mole of oxygen is used. Therefore, to produce 3.00 moles of water, 1.50 moles of oxygen must be used.
3)2.5 moles H2O x 2 moles H2 / 2 moles H2O = 2.5 moles H2
2.5 moles H2
Based on the balanced equation, for every 2 moles of water produced, 2 moles of hydrogen are used. Therefore, to produce 2.5 moles of water, 2.5 moles of hydrogen must be used.
4)4.00 grams H2 x 1 mole H2 / 2.016 grams H2 x 2 moles H2O / 2 moles H2 = 3.97 grams H2O
3.97 grams H2O
First, the number of moles of H2 used is calculated using the molar mass of H2. Then, the number of moles of H2O produced is calculated based on the balanced equation. Finally, the mass of H2O produced is calculated using the molar mass of H2O.
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Ironwood Bank is offering a 30-year mortgage with an APR of 6.00% based on monthly compounding. If you plan to borrow $160,000, what will be your monthly payment? The loan payment is (Round to the nearest cent)
Your monthly payment for a 30-year mortgage with a principal of $160,000 and an APR of 6.00% based on monthly compounding will be $959.60.
To calculate the monthly payment, we can use the formula for mortgage payments:
P = L[c(1 + c)^n]/[(1 + c)^n - 1]
where P is the monthly payment, L is the principal (loan amount), c is the monthly interest rate (APR/12), and n is the total number of payments (30 years x 12 months = 360).
Plugging in the values, we get:
P = 160000[(0.06/12)(1 + 0.06/12)^360]/[(1 + 0.06/12)^360 - 1]
P = $959.60
Therefore, the monthly payment for the given mortgage is $959.60.
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For the following chemical equation: Zn(NO3)2(aq) + H2S(aq) + ZnS(8) + 2HNO3(aq) Which will NOT be involved in the net ionic equation? Select the correct answer below: O NO, (aq) Zn?! (aq) Os (aq) ZnS (s) B FEEDBACK MORE INST ges/technical-information?module_item_id=2163467 W
The species that will not be involved in the net ionic equation are Zn²⁺(aq) and NO₃⁻(aq).
In order to determine which species will not be involved in the net ionic equation, we first need to write out the complete ionic equation. This equation shows all of the soluble ionic species in the reaction as separate ions. The complete ionic equation for the given reaction is:
Zn²⁺(aq) + 2NO₃⁻(aq) + 2H⁺(aq) + S²⁻(aq) → ZnS(s) + 2H⁺(aq) + 2NO₃⁻(aq)
From this equation, we can see that all of the species are involved in the reaction, including NO₃⁻(aq), Zn²⁺(aq), S²⁻(aq), and ZnS(s). However, the question asks which species will not be involved in the net ionic equation.
The net ionic equation is obtained by canceling out any spectator ions, which are ions that are present on both sides of the equation and do not participate in the reaction. In this case, the spectator ions are Zn²⁺(aq) and NO₃⁻(aq), which are present on both sides of the equation. The net ionic equation is therefore:
S²⁻(aq) + 2H⁺(aq) → H₂S(aq)
From this equation, we can see that the species that will not be involved in the net ionic equation are Zn²⁺(aq) and NO₃⁻(aq). The species that will be involved in the net ionic equation are S²⁻(aq), H⁺(aq), and H₂S(aq).
In summary, the species that will not be involved in the net ionic equation are Zn²⁺(aq) and NO₃⁻(aq), while the species that will be involved in the net ionic equation are S²⁻(aq), H⁺(aq), and H₂S(aq).
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The Ksp of nickel hydroxide =6.0×10−16 M.
You may want to reference(Pages 744 - 750) Section 17.5 while completing this problem.
1.) Calculate the molar solubility of Ni(OH)2 when buffered at pH= 8.0.
Express your answer using one significant figure.
2.) Calculate the molar solubility of Ni(OH)2 when buffered at pH= 10.3.
Express your answer using one significant figure.
3.) Calculate the molar solubility of Ni(OH)2 when buffered at pH= 11.9.
Express your answer using one significant figure.
Answer: The molar solubility of Ni(OH)2 when buffered at pH=8.0 is 1.0×10^-7 M.
The molar solubility of Ni(OH)2 when buffered at pH=10.3 is 1.6×10^-6 M.
The molar solubility of Ni(OH)2 when buffered at pH=11.9 is 2.5×10^-5 M.
Explanation: The solubility of a sparingly soluble salt is affected by pH of the solution. At a given pH, the solubility of the salt is related to the solubility product constant, Ksp, of the salt. The expression for the solubility product constant is:
Ksp = [Ni2+][OH-]^2
where [Ni2+] and [OH-] are the concentrations of Ni2+ and OH- ions, respectively.
The solubility of Ni(OH)2 in water is 1.4 × 10^-15 M.
At pH 8.0, Ni(OH)2 is insoluble as the pH is below the pKa of the hydroxide ion. Therefore, the molar solubility of Ni(OH)2 is 0.
At pH 10.3, the concentration of OH- ions is 5.0 × 10^-4 M. Thus, the concentration of Ni2+ ions is given by:
Ksp = [Ni2+][OH-]^2
1.4 × 10^-15 = [Ni2+][5.0 × 10^-4]^2
[Ni2+] = 5.6 × 10^-8 M
Therefore, the molar solubility of Ni(OH)2 is 5.6 × 10^-8 M.
At pH 11.9, the concentration of OH- ions is 5.0 × 10^-3 M. Thus, the concentration of Ni2+ ions is given by:
Ksp = [Ni2+][OH-]^2
1.4 × 10^-15 = [Ni2+][5.0 × 10^-3]^2
[Ni2+] = 5.6 × 10^-12 M
Therefore, the molar solubility of Ni(OH)2 is 5.6 × 10^-12 M.
calculate the enthalpy change for the formation of lead chloride by the reaction of lead chloride with chlorine
The enthalpy change for the formation of lead chloride by the reaction of lead chloride with chlorine is -11.6 kJ/mol.
It can be calculated by using Hess's Law. We can break down the overall reaction into two steps: the first is the dissociation of lead chloride into lead ions and chloride ions, and the second is the reaction of chlorine with the chloride ions to form lead chloride.
The enthalpy change for the first step, the dissociation of lead chloride, is given as ΔH = +92.8 kJ/mol. The enthalpy change for the second step, the reaction of chlorine with the chloride ions, is given as ΔH = -104.4 kJ/mol.
To calculate the enthalpy change for the overall reaction, we add the enthalpy changes for the two steps:
ΔH = ΔH1 + ΔH2
ΔH = (+92.8 kJ/mol) + (-104.4 kJ/mol)
ΔH = -11.6 kJ/mol
Therefore, by using formula of the enthalpy change, the result for the formation of lead chloride is -11.6 kJ/mol.
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Use data from CRC_Std_Thermodyn_Substances and CRC_Std_Thermodyn_Aqueous-Ions to calculate ΔrH∘ΔrH∘ (in kj/mol) for the following at 25 ∘∘C.
2CaC2O4(s)⟶4CO(g)+O2(g)+2CaO(s)
The ΔrH∘ for the given reaction at 25∘C is -1,484.0 kJ/mol.
To calculate ΔrH∘ for the given reaction, we need to use the standard enthalpy of formation values for the reactants and products.
2CaC2O4(s)⟶4CO(g)+O2(g)+2CaO(s)
The standard enthalpy of formation values can be found in the CRC_Std_Thermodyn_Substances and CRC_Std_Thermodyn_Aqueous-Ions tables.
Reactants:
2CaC2O4(s) -> ΔfH∘ = -2,239.0 kJ/mol
Products:
4CO(g) -> ΔfH∘ = -1,103.0 kJ/mol
O2(g) -> ΔfH∘ = 0 kJ/mol
2CaO(s) -> ΔfH∘ = -1,264.0 kJ/mol
ΔrH∘ = ΣΔfH∘(products) - ΣΔfH∘(reactants)
ΔrH∘ = [4(-1,103.0 kJ/mol) + 0 kJ/mol + 2(-1,264.0 kJ/mol)] - [2(-2,239.0 kJ/mol)]
ΔrH∘ = -1,484.0 kJ/mol
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