Answer:
The correct options are a, b and d
Explanation:
A catalyst is a substance that increases the rate of a chemical reaction by reducing the activation energy. Le Catelier's principle explains how a substance or an "action" can affect a reaction in equilibrium.
The principle states that when a change is made to the conditions of a reacting system at equilibrium, the position of the equilibrium moves to counteract the change made. These changes are change in temperature, pressure, volume and/or concentration. These changes will either cause the equilibrium to shift forward or backward.
However, the presence of a catalyst DOES NOT affect a chemical equilibrium/equilibrium constant nor does it affect the reaction quotient because the same amount of reactants and products are available just as in uncatalyzed reaction except that the reaction proceeds faster (which does not affect equilibrium).
The rate of reaction is given as the time required by the reactant to convert into the product. The addition of catalyst increases the rate of reaction, while the reaction quotient and the equilibrium remain unaffected.
What is a catalyst?A catalyst is a chemical or compound that adds to the reaction and lowers the activation energy by providing an alternative path to the reaction.
The catalyst takes part in the reaction but did not consume in the chemical reaction.
The equilibrium and the reaction quotient are dependent on the conversion of the reactant to the product. The catalyst is not used in the reaction and thus did not affect the reaction quotient or the equilibrium.
Hence, options A, B, and D are correct for the use of catalysts in the chemical reaction.
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A quantity of 1.435 g of naphthalene , was burned in a constant-volume bomb calorimeter. Consequently, the temperature of the water rose from 20.28oC to 25.95oC If the heat capacity of the bomb plus water was , calculate the heat of combustion of naphthalene on a molar basis; that is, find the molar heat of combustion.
Answer:
molar heat of combustion = -5156 *10³ kJ/mol
Explanation:
A quantity of 1.435 g of naphthalene , was burned in a constant-volume bomb calorimeter. Consequently, the temperature of the water rose from 20.28oC to 25.95oC If the heat capacity of the bomb plus water was 10.17 kJ/°C, calculate the heat of combustion of naphthalene on a molar basis; that is, find the molar heat of combustion.
Step 1: Data given
Mass of naphthalene = 1.435 grams
Initial temperature of water = 20.28 °C
Final temperature of water = 25.95 °C
heat capacity of the bomb plus water was 10.17 kJ/°C
Molar mass naphtalene = 128.2 g/mol
Step 2:
Qcal = Ccal * ΔT
⇒with Qcal =the heat of combustion
⇒with Ccal = heat capacity of the bomb plus water = 10.17 kJ/°C
⇒with ΔT = the difference in temperature = T2 - T1 = 25.95 - 20.28 = 5.67°C
Qcal = 10.17 kJ/°C * 5.67 °C
Qcal = 57.7 kJ
Step 3: Calculate moles
Moles naphthalene = 1.435 grams / 128.2 g/mol
Moles naphthalene = 0.01119 moles
Step 4: Calculate the molar heat of combustion
molar heat of combustion = Qcal/ moles
molar heat of combustion = -57.7 kJ/ 0.01119 moles
molar heat of combustion = -5156 *10³ kJ/mol
What is the gravitational potential energy of a 1500-kg truck resting on top of a 550-m hill on earth?( earth’s gravitational pull is 9.8m/s2).
Answer:
E = 8085 kJ
Explanation:
Given that,
The mass of a truck, m = 1500 kg
Height, h = 550 m
We need to find the gravitational potential energy of the truck. It can be calculated as follows :
[tex]E=mgh[/tex]
Put all the values,
[tex]E=1500\times 9.8\times 550\\\\E=8085000\ J\\\\or\\\\E=8085\ kJ[/tex]
So, the gravitational potential energy is 8085 kJ.
Cathode rays are beams of?
electrons
protons
anions
neutrons
Answer:
Electrons
Explanation:
Electrons are produced when light with enough energy is directed onto the cathode where electrons are ejected as beam towards the screen.
2. What is the conductivity of lead as compared to silver?
O A. 7
OB. 15
O C. 30
O D. 61
PLEASE HELP!!!
Explain the various factors that impact the solubility of substances in water.
(At least 4 sentences) :)
The various factors that impact the solubility of substances in water are - nature of solute and solvent, temperature, pressure and pH.
The solubility of substances in water is influenced by several factors:
Nature of the solute and solvent: The chemical properties of both the solute and the solvent play a significant role. Substances with similar polarities and intermolecular forces tend to dissolve more readily in water. Polar solutes, such as salts and sugars, dissolve well in polar solvents like water, whereas nonpolar solutes, like oils and fats, have low solubility in water.Temperature: In general, an increase in temperature enhances the solubility of solid solutes in water, as it provides more energy for the solute particles to overcome intermolecular forces and mix with the solvent. However, the effect of temperature on solubility can vary depending on the specific solute. For some solutes, such as gases, solubility decreases with increasing temperature.Pressure (for gases): The solubility of gases in water is influenced by pressure. According to Henry's law, the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas above the liquid. Therefore, an increase in pressure generally leads to an increase in gas solubility in water.pH: The pH of the solution can impact the solubility of certain substances. For example, the solubility of acidic or basic compounds may change with varying pH levels.Learn more about Solubility, here:
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An atom has 20 electrons. Find out
i. It’s atomic numbers and total number of p-electrons
ii. The value of azimuthal quantum number (l) and magnetic quantum number (m) of the 19th electron of the atom.
iii. It’s group position in the periodic table.
Answer:
it's atomic number is 5 and total number is 10
The atom has an atomic number of 20 and has a total of 12 p electrons.
The azimuthal quantum number (l) of the 19th electron is 0 and the magnetic quantum number (m) of the 19th electron is 0.
It is an element of group 2
The number of electrons in the neutral atom is equal to the number of protons and is also the atomic number of an atom.
An atom is known to be electrically neutral. This is because the number of electrons in the atom is equal to the number of protons in the neutral atom.
The number of protons in the neutral atom is called the atomic number of the atom.
For an element that has 20 electrons, its electronic configuration is;
1s2 2s2 2p6 3s2 3p6 4s2.
The 19th electron is in the 4s orbital hence both the azimuthal and magnetic quantum numbers are zero.
The element has outermost electron configuration ns2 so it mus belong to group 2 of the periodic table.
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Determine the molarity of the sodium ions when 78.0 g Na2S is dissolved in water for a final volume of 1.0 L.
Answer:
[Na⁺] = 1.99 M
Explanation:
Na₂S is a ionic salt that can be dissociated.
Dissociation equation is:
Na₂S → 2Na⁺ + S⁻²
1 mol of sodium sulfide can give 2 moles of sodium cation.
We convert moles of salt: 78 g . 1mol / 78.06 g = 0.999 moles
As ratio is 1:2, after dissociation we have (0.999 . 2) = 1.998 moles of Na⁺
Molarity is a type of concentration.
It indicates moles of solute in 1 L of solution and in this case, we have 1 L as final voulme.
Moles of Na⁺ are 1.998 moles. Then molarity (mol/L) is:
M =1.99 mol/L
following this list of common polyatomic ions what would be the charge for aluminum nitrate?
Nitrate NO3
Phosphate PO43,
Sulfate SO4 -2
acetate C2H3O2-1
Ammonium NH4.
Chromate CrO4-2
Carbonate C03-2
Dichromate CrO7-2
Permanganate MnO4-1
What would be the correct answer for Aluminum nitrate
Answer:
Nitrate NO3
here's your answer, hope it helps you
Para formar bronce, se mezclan 150g de cobre a 1100°C y 35g de estaño a 560°C. Determine la temperatura final del sistema.
Dato: Ce Cu: 0,093 cal/gºC; Ce Sn: 0,060 cal/gºC
URGENTEEEE
Answer:
La temperatura final del sistema es 1029,346 °C.
Explanation:
Asumamos que el sistema conformado por el cobre y el estaño no tiene interacciones con sus alrededores. Por la Primera Ley de la Termodinámica, el cobre cede calor al estaño con tal de alcanzar el equilibrio térmico. El cobre se encuentra inicialmente en su punto de fusión, mientras que el estaño está por encima de ese punto, de modo que la transferencia de calor es esencialmente sensible:
[tex]m_{Cu}\cdot c_{Cu}\cdot (T-T_{Cu}) = m_{Sn}\cdot c_{Sn}\cdot (T_{Sn}-T)[/tex]
[tex](m_{Cu}\cdot c_{Cu} + m_{Sn}\cdot c_{Sn})\cdot T = m_{Sn}\cdot c_{Sn}\cdot T_{Sn} + m_{Cu}\cdot c_{Cu}\cdot T_{Cu}[/tex]
[tex]T = \frac{m_{Sn}\cdot c_{Sn}\cdot T_{Sn}+m_{Cu}\cdot c_{Cu}\cdot T_{Cu}}{m_{Cu}\cdot c_{Cu}+m_{Sn}\cdot c_{Sn}}[/tex] (1)
Donde:
[tex]m_{Sn}[/tex] - Masa del estaño, en gramos.
[tex]m_{Cu}[/tex] - Masa del cobre, en gramos.
[tex]c_{Sn}[/tex] - Calor específico del estaño, en calorías por gramo-grados Celsius.
[tex]c_{Cu}[/tex] - Calor específico del cobre, en calorías por gramo-grados Celsius.
[tex]T_{Sn}[/tex] - Temperatura inicial del estaño, en grados Celsius.
[tex]T_{Cu}[/tex] - Temperatura inicial del cobre, en grados Celsius.
Si sabemos que [tex]m_{Cu} = 150\,g[/tex], [tex]m_{Sn} = 35\,g[/tex], [tex]c_{Cu} = 0,093\,\frac{cal}{g\cdot ^{\circ}C}[/tex], [tex]c_{Sn} = 0,060\,\frac{cal}{g\cdot ^{\circ}C}[/tex], [tex]T_{Sn} = 560\,^{\circ}C[/tex] y [tex]T_{Cu} = 1100\,^{\circ}C[/tex], entonces la temperatura final del sistema es:
[tex]T = \frac{(35\,g)\cdot \left(0,060\,\frac{cal}{g\cdot ^{\circ}C} \right)\cdot (560\,^{\circ}C)+(150\,g)\cdot \left(0,093\,\frac{cal}{g\cdot ^{\circ}C} \right)\cdot (1100\,^{\circ}C)}{(35\,g)\cdot \left(0,060\,\frac{cal}{g\cdot ^{\circ}C} \right)+(150\,g)\cdot \left(0,093\,\frac{cal}{g\cdot ^{\circ}C} \right)}[/tex]
[tex]T = 1029,346\,^{\circ}C[/tex]
La temperatura final del sistema es 1029,346 °C.
During a reaction, ΔH for reactants is −750 kJ/mol and ΔH for products is 920 kJ/mol. Which statement is correct about the reaction? (5 points)
Group of answer choices
It is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
It is endothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
It is exothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
It is exothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
Answer: The statement it is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed, is true.
Explanation:
A chemical reaction in which heat energy is released is called an exothermic reaction. For exothermic reactions, the value of [tex]\Delta H[/tex] is always negative.
A chemical reaction in which heat energy is absorbed is called an endothermic reaction. For endothermic reaction, the value of [tex]\Delta H[/tex] is always positive.
In endothermic reactions, energy required for breaking the bonds between reactants is less than the energy when products are formed due to which the value of [tex]\Delta H[/tex] remains positive.
Thus, we can conclude that the statement it is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed, is true.
It is endothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed. The correct option is B.
The above reaction is endothermic because more energy is produced when new bonds form in the products (H = 920 kJ/mol) than is required to break bonds in the reactants (H = -750 kJ/mol).
In an endothermic process, more energy than is generated during bond creation is absorbed from the environment to dissolve existing bonds. This causes a net absorption of energy, which cools the system.
The reaction takes more energy than it releases, proving its endothermic nature, as seen by the positive difference between the energy needed to dissolve bonds and the energy released during bond formation.
Thus, the correct option is B.
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Your question seems incomplete, the probable complete question is:
During a reaction, ΔH for reactants is −750 kJ/mol and ΔH for products is 920 kJ/mol. Which statement is correct about the reaction? (5 points)
Group of answer choices
A. It is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
B. It is endothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
C. It is exothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed.
D. It is exothermic because the energy required to break bonds in the reactants is greater than the energy released when the products are formed.
What is bond energy
atomaticity of chlorine 1) 2, 2)1, 3) 32 , 4) 4.
Answer:
ATOMICITY OF CHLORINE IS 2Explanation:
Atomicity is defined as the total number of atoms present in a molecule.
when (S)-3-bromo-2,3-dimethylpentane is treated with sodium chloride with water as the solvent, the products formed are ___________. *Select all that apply
Answer:
(S)-3-chloro-2,3-dimethylpentane
Explanation:
When sodium chloride is treated with bromo dimethylpentane in presence of water, then chloro dimethylpentane is formed. This chemical reaction is stable reaction in water because of its solvency.
Write the number of sig. fig. in four numbers given in the sentence below. An (one) octopus has 8 legs. 13 octopi have 104 legs.
Give four answers.
A. Infinity, Infinity, Infinity, Infinity
B. 1, 1, 2, 3
C. Infinity, Infinity, 2, 3
D. No answer text provided.
Answer:
1, 1, 2, 3
Explanation:
The numbers 1 and 8 both have 1 sig. fig.
The number 13 has 2 sig. figs.
The number 104 has 3 sig. figs.
Water has a density of 1.00 g/mL. If you put an object that has a density of 0.79 g/mL into water, it will sink to the
bottom.
ANSWER:
True
False
Answer:
False
Explanation:
An object with a density greater than 1.00g/mL (greater than the density of water) will sink. An object with a density less than the density of water, will float.
If the water has a density of 1.00 g/mL. If you put an object that has a density of 0.79 g/mL into water, it will sink to the bottom, this statement is false.
What is density?The density of an actual content is its mass per unit volume. The most common symbol for density is d, but the Latin letter D can also be used.
Three of an object's most fundamental properties are mass, volume, and density. Mass describes how heavy something is, volume describes its size, and density is defined as mass divided by volume.
The density of something is a measure of how heavy it is in relation to its size. When an artifact is more dense than water, it plunges; when an object is less dense than water, it floats.
Density is a property of a substance that is independent of the amount of substance.
As in the given scenario, water is having density 1 g/mL and object in having density less then it so it will float on water.
Thus, the given statement is false as the material will not sink, rather it will float on water.
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Write a balanced chemical equation for the reaction of aqueous potassium hydroxide with aqueous iron(III) chloride to form solid iron(III) hydroxide and aqueous potassium chloride. Express your answer as a chemical equation including phases. nothing A chemical reaction does not occur for this question.
Answer:
3KOH(aq) + FeCl3(aq) --------> Fe(OH)3 + 3KCl
Explanation:
The rule for balancing chemical equations is that the number of atoms of each element must be the same on both sides of the reaction equation.
Hence, the two reactants are potassium hydroxide and aqueous iron(III) chloride.
The balanced molecular reaction equation is;
3KOH(aq) + FeCl3(aq) --------> Fe(OH)3 + 3KCl
what class of organic compound is formed when cyclopentanone reacts with ethylamine in the presence of trace acid
The question is incomplete, the complete question is;
What functional group results when cyclopentanone reacts with ethylamine in the presence of trace acid? A) cyanohydrin B) semicarbazone C) imine D) enamine E) oxime
Answer:
imine
Explanation:
An imine is an unsaturated amine. An imine contains the carbon- nitrogen double bond.
Imines are obtained when a carbonyl compound is condensed with NH3 or an amine. The reaction involves several steps in its mechanism.
Since cyclopentanone is a ketone (carbonyl compound) and ethylamine is an amine,in the presence of trace acid, condensation of the two compounds occur to yield an imine
from the following equation in which decomposition of CaCO3 takes place, give your justification. CaCO3 gives Ca +CO2
Answer:
CaCO₃(s) => CaO(s) + CO₂(g) ... GpIIA Decomp
Explanation:
Metallic Carbonates decompose into a metallic oxide and carbon dioxide.
Examples:
Na₂CO₃(s) => Na₂O(s) + CO₂(g) ... GpIA Decomp
MgCO₃(s) => MgO(s) + CO₂(g) ... GpIIA Decomp
A compound that contains only carbon, hydrogen, and oxygen is 58.8% C and 9.87% H by mass. What is the empirical formula of this substance
Answer: The empirical formula of the compound becomes [tex]C_5H_{10}O_2[/tex]
Explanation:
The empirical formula is the chemical formula of the simplest ratio of the number of atoms of each element present in a compound.
Let the mass of the compound be 100 g
Given values:
% of C = 58.8%
% of H = 9.87%
% of O = [100 - 58.8 - 9.87] = 31.33%
Mass of C = 58.8 g
Mass of H = 9.87 g
Mass of O = 31.33 g
The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
To formulate the empirical formula, we need to follow some steps:
Step 1: Converting the given masses into moles.Molar mass of C = 12 g/mol
Molar mass of H = 1 g/mol
Molar mass of O = 16 g/mol
Putting values in equation 1, we get:
[tex]\text{Moles of C}=\frac{58.8g}{12g/mol}=4.9 mol[/tex]
[tex]\text{Moles of H}=\frac{9.87g}{1g/mol}=9.87 mol[/tex]
[tex]\text{Moles of O}=\frac{31.33g}{16g/mol}=1.96mol[/tex]
Step 2: Calculating the mole ratio of the given elements.Calculating the mole fraction of each element by dividing the calculated moles by the least calculated number of moles that is 1.96 moles
[tex]\text{Mole fraction of C}=\frac{4.9}{1.96}=2.5[/tex]
[tex]\text{Mole fraction of H}=\frac{9.87}{1.96}=5.03\approx 5[/tex]
[tex]\text{Mole fraction of O}=\frac{1.96}{1.96}=1[/tex]
Converting the mole fraction into whole numbers by multiplying them with 2.
[tex]\text{Mole fraction of C}=2.5\times 2=5[/tex]
[tex]\text{Mole fraction of H}=5\times 2=10[/tex]
[tex]\text{Mole fraction of O}=1\times 2=2[/tex]
Step 3: Taking the mole ratio as their subscripts.The ratio of C : H : O = 5 : 10 : 2
Hence, the empirical formula of the compound becomes [tex]C_5H_{10}O_2[/tex]
The empirical formula of the substance is[tex]C_5H_{10}O_2[/tex].
Explanation:
Given:
A compound made up of 58.8% of carbon, 9.87% hydrogen, and oxygen.
To find:
The empirical formula of this substance.
Solution
The percentage of carbon in a given substance by mass = 58.8%
The percentage of hydrogen in a given substance by mass = 9.87%
The percentage of oxygen in a given substance by mass :
[tex]= 100\%-58.8\%- 9.87\%=31.33\%[/tex]
Consider 100 grams of a substance.
In 100 grams of substance:
The mass of carbon =58.8% of 100 g = 58.8 g
The mass of hydrogen = 9.87% of 100 g = 9.87 g
The mass of oxygen = 31.33% of 100 g= 31.33 g
The moles of carbon [tex]=\frac{58.8 g}{12.0107 g/mol}=4.90 mol[/tex]
The moles of hydrogen[tex]=\frac{9.87g}{1.00784g/mol}=9.79 mol[/tex]
The moles of oxygen[tex]=\frac{31.33g}{15.999g/mol}=1.96 mol[/tex]
let the empirical formula of the substance = [tex]C_xH_yO_z[/tex]
The value of subscript x:
[tex]=\frac{4.90 mol}{1.96 mol}=2.5[/tex]
The value of subscript y:
[tex]=\frac{9.79mol}{1.96 mol}=5[/tex]
The value of subscript z:
[tex]=\frac{1.96mol}{1.96 mol}=1[/tex]
The empirical formula of a substance :
[tex]C_{2.5}H_5O_1=C_{\frac{25}{10}}H_5O_1=C_{25}H_{50}O_{10}[/tex]
Reducing to the lowest whole numbers:
[tex]C_{25}H_{50}O_{10}=C_5H_{10}O_2[/tex]
The empirical formula of the substance is [tex]C_5H_{10}O_2[/tex].
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What are the uses of Sulphuric acid?
Answer:
The major use of sulfuric acid is in the production of fertilizers, e.g., superphosphate of lime and ammonium sulfate. It is widely used in the manufacture of chemicals, e.g., in making hydrochloric acid, nitric acid, sulfate salts, synthetic detergents, dyes and pigments, explosives, and drugs.
The major use of sulfuric acid is in the production of fertilizers, e.g., superphosphate of lime and ammonium sulfate. It is widely used in the manufacture of chemicals, e.g., in making hydrochloric acid, nitric acid, sulfate salts, synthetic detergents, dyes and pigments, explosives, and drugs.
A student needed to make a 3 g/L NaCl solution. The student weighed 3 g of NaCl in a beaker and measured 1 L of water in a 1L volumetric flask that was labeled TC. The student then added the water to the beaker containing the NaCl. What errors did this student make? Describe how this can be performed properly.
Answer:
The answer is in the explanation.
Explanation:
A solution is defined as the homogeneous mixture of a solute (In this case, NaCl) and the solvent (water).
To prepare 1L of the solution, the student can weigh the 3g of NaCl in the volumetric flask but need to add slowly water to dissolve the NaCl (That is very soluble in water). When all NaCl is dissolved the student must transfer the solution to the 1L volumetric flask. Then, you must add more water to the beaker until "Clean" all the solute of the beaker to transfer it completely to the volumetric flask.
Platinum is one of the most dense elements (d = 21.5 g/cm3). What is the volume of a 10.0 g sample of the metal?
Answer:
0.465
Explanation:
To find the volume of a substance, divide the mass by the density.
M/D = V
10.0 / 21.5 = 0.4651163
Then round to 3 significant figures: and the density is 0.465
when a polar bond is formed between 2 atoms which atom receives a partial positive charge
Answer:
The less electronegative atom
Explanation:
Water contains polar bonds. Water is made up of oxygen and hydrogen. Oxygen is more electronegative then hydrogen so it is partial negative (because electron spend more time around oxygen in the polar bond), whereas, hydrogen has a partial positive charge as it is less electronegative (electrons spend less time around hydrogen in this polar bond).
11) Methane and oxygen react to form carbon dioxide and water. What mass of water is formed if 0.80 g of methane reacts with 3.2 g of oxygen to produce 2.2 g of carbon dioxide
What mass of NaOH would need to be dissolved in 500.0 mL of water to produce a solution with a pH of 12.40
Answer:
0.5024 g
Explanation:
Step 1: Calculate the concentration of H⁺
We will use the definition of pH.
pH = -log [H⁺]
[H⁺] = antilog -pH = antilog -12.40 = 3.981 × 10⁻¹³ M
Step 2: Calculate the concentration of OH⁻
We will use the ionic product of water expression.
[H⁺] [OH⁻] = 10⁻¹⁴
[OH⁻] = 10⁻¹⁴/[H⁺] = 10⁻¹⁴/3.981 × 10⁻¹³ = 0.02512 M
Step 3: Calculate the initial concentration of NaOH
NaOH is a strong base and the molar ratio of NaOH to OH⁻is 1:1. Thus, the initial concentration of NaOH is 1/1 × 0.02512 M = 0.02512 M.
Step 4: Calculate the moles of NaOH
We will use the definition of molarity.
M = moles of NaOH/liters of solution
moles of NaOH = M × liters of solution
moles of NaOH = 0.02512 mol/L × 0.5000 L = 0.01256 mol
Step 5: Calculate the mass of 0.01256 moles of NaOH
The molar mass of NaOH is 40.00 g/mol.
0.01256 mol × 40.00 g/mol = 0.5024 g
Classify each of the following as either macroscopic, microscopic or particulate:
a. a red blood cell.
b. a sugar molecule.
c. baking powder.
Answer:
Classify each of the following as either macroscopic, microscopic or particulate:
a. a red blood cell.
b. a sugar molecule.
c. baking powder.
Explanation:
a. A red blood cell is a microscopic particle.
It can be viewed under a microscope.
b. A sugar molecule is also a microscopic substance.
It can be viewed under a microscope.
c. Baking powder is macroscopic substance.
help with the following would be greatly appreciated!
What mass of steam initially at 120oC is needed to warm 200g of water in a glass container from 20.0 oC to 50.0 oC
Complete question:
What mass of steam initially at 120 ⁰C is needed to warm 200g of water in a 100 g glass container from 20.0 oC to 50.0 ⁰C
Answer:
the initial mass of the steam is 10.82 g
Explanation:
Given;
mass of water, m₁ = 200 g
mass of the glass, m₂ = 100 g
temperature of the steam = 120 ⁰C
initial temperature of the water, 20⁰ C
final temperature of the water, = 50⁰ C
let the mass of the steam = m
specific heat capacity of water c = 1 cal/g ⁰ C
specific heat capacity of glass c₂ = 0.2 cal/g ⁰ C
laten heat of vaporization of steam L = 540 cal/g
Apply principle of conservation energy;
Heat given off by the steam = Heat absorbed by water + heat absorbed by glass
[tex]mc\Delta T_1 + mL + mc\Delta T_2 = m_1c\Delta T_3 + m_2c_2\Delta T_3\\\\mc\Delta T_1 + mL + mc\Delta T_2 = [m_1c + m_2c_2]\Delta T_3[/tex]
m(1) (120 - 100) + m(540) + m(1) (100 - 50) = [200(1) + 100(0.2)] (50 - 20)
20m + 540m + 50m = 6600
610 m = 6600
m = 6600 / 610
m = 10.82 g
Therefore, the initial mass of the steam is 10.82 g
Which one of the following compounds does NOT obey the "octet rule"?
LiF
BF3
H20
CBr4
Answer:
BF3
Explanation:
The octet rule describes atoms' preference and affinity for having eight (8) electrons in their valence shell. Whenever an atom is encircled by eight(8) electrons, it forms a stable configuration. This octet can be composed of its' own electrons as well as some shared electrons. In the periodic table, only the s-block and p-block electrons are considered for the octet rule.
However, out of the given option, only BF3 does not comply with the octet rule: This is because the Bromine contains 2 lone pairs of electrons and 3 other shared bonded pairs of electrons with Flourine making a total of 10 electrons in the valence shell and which does not conform with the octet rule.
Help pls!!!
For groups 13 through 18, the number of valence electrons is equal to the group number
a. minus 10
b. minus the period number
c. plus 1
d. plus the period number
Answer:
a. minus 10
Explanation:
An element in group 13 = Boron ,valence electrons = 3 , therefore, valence electrons in group 13 = group no. -10
An element in group 18 = Neon, valence electrons = 8 , therefore, valence electrons in group 18 = group no. - 10
For groups 13 through 18, the number of valence electrons in an atom is equal to the group number minus 10. Therefore, option (A) is correct.
What is a valence electron?Valence electrons in an atom can be described as the electrons occupying the outer most electron shell of an atom while the electrons in the inner shell are core electrons. Lewis structures can be helpful to calculate the number of valence electrons.
Valence electrons can be filled in several electron shells as they are caused interaction between atoms and responsible for the formation of chemical bonds. Only valence electrons can contribute to the formation of a chemical bond and decide the reactivity of the element.
The general electronic configuration of group 13 is ns²np¹ has three valence electrons. It can be determined as group number - 10 = 13 - 10 = 3.
The general electronic configuration of group 18 is ns²np⁶ has eight valence electrons. It can be determined as group number - 10 = 18 - 10 = 8.
Learn more about valence electrons, here:
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