Chem Questions

1) Determine the mass of RbCN required to prepare a 370 mL solution which is 0.12 M RbCN (MW = 112 g/mol).


2) Determine the mass of RbCN required to prepare a 246 mL solution which is 0.12 M RbCN (MW = 112 g/mol).

3) What does a 1-molar solution of CaCl_2 contain?

4) Calculate the empirical formula for a chemical compound that gives the following analysis: 12.6 percent lithium, 29.2 percent sulfur, and 58.2 percent oxygen.

5) Calculate the empirical formula for a chemical compound that gives the following analysis: 65.2 g scandium and 34.8 g oxygen.

The oxygen consumption for a burmese python at 20 contractions per minute 5,30,35,10,15,20,25 contractions per minute.

The Eastern Hemisphere's tropical and subtropical regions are home to the genus Python, a family of constricting snakes. For non-venomous flecked snakes, François Marie Daudin suggested the name "Python" in 1803. There are now 10 recognized python species. A new species has been established, and three previously recognized python subspecies have been elevated.

Ythons lack venom, and colubrids (rear-fanged snakes) either lack venom entirely or have a weak venom. It is important to take venomous elapid (front-fanged snake) bites seriously and treat them accordingly. Massive snakes called pythons have a brutal killing style. These snakes, like other strong constrictors like anacondas, will capture their victims with their mouths and wrap around them.

What was the oxygen consumption for a burmese python at 20 contractions per minute?

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The polar water molecules attract the oppositely assessed polar areas of the sucrose molecules and pull them away, resulting in dissolving. Since the ions in salt and the molecules in sugar are very different, their solubilities tend to be additional.

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The mass of this ion is 1.16*10^-26kg.

To find the answer, we have to know about the force acting on a particle circulating in a uniform magnetic field.

                                  [tex]F_c=F_B\\\frac{mv^2}{r} =qvB\\[/tex]

                   [tex]m=\frac{qBr}{v} =\frac{2*1.67*10^{-19}*0.8*30*10^{-2}}{6.9*10^6} \\m=1.16*10^{-26}kg[/tex]

Thus, we can conclude that, the mass of this ion is 1.16*10^-26kg.

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Answer:

0.71 moles KI

Explanation:

At STP, there should be 1.0 moles at 22.4 L. However, there are only 8.0 L of I₂. Therefore, we must set up a proportion to find the correct moles of I₂.

[tex]\frac{1 mole}{22.4 L} =\frac{? moles}{8.0 L}[/tex]                                <----- Proportion

[tex]8.0 = 22.4(? moles)[/tex]                         <----- Cross multiply

[tex]0.36 = ? moles[/tex]                                 <----- Divide both sides by 22.4

To find the moles of KI, you can use the mole-to-mole ratio from the balanced equation coefficients. The final answer should have 2 sig figs.

2 KI(aq) + Cl₂(g) ---> 2KCl(aq) + 1 I₂(g)
^                                                   ^

0.36 moles I₂          2 moles KI
----------------------  x  --------------------  =  0.71 moles KI
                                   1 mole I₂

Answer: 0.71 moles KI

Explanation:

144 mL of fluorine gas is required to react with 1.28 g of calcium bromide to form calcium fluoride and bromine gas at STP.

The ideal gas law states that the pressure of gas is directly proportional to the volume and temperature of the gas.

PV = nRT

where,

P = Presure

V = Volume in liters

n = number of moles of gas

R = Ideal gas constant

T = temperature in Kelvin

Here,

P = 1 atm  [At STP]

R = 0.0821 atm.L/mol.K

T = 273 K  [At STP]

Now first find the number of moles

F₂  +  CaBr₂  →  CaF₂  +  Br₂

Here 1 mole of F₂ reacts with 1 mole of CaBr₂.

So,  199.89 g CaBr₂ reacts with  = 1 mole of F₂

1.28 g of CaBr₂ will react with = n mole of F₂

[tex]n = \frac{1.28\g \times 1\ \text{mole}}{199.89\ g}[/tex]

n = 0.0064 mole

Now put the value in above equation we get

PV = nRT

1 atm × V = 0.0064 × 0.0821 atm.L/mol.K × 273 K

V = 0.1434 L

V ≈ 144 mL

Thus from the above conclusion we can say that 144 mL of fluorine gas is required to react with 1.28 g of calcium bromide to form calcium fluoride and bromine gas at STP.

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The partial pressure of gas C is 0.54atm. The correct option is D.

The pressure that one of the gases in a mixture would exert if it were in the same volume on its own.

The total pressure of A, B and C is 6.11 atm.

The partial pressure of A is 1.68 atm

The partial pressure of B is 3.89 atm.

Total pressure = sum of partial pressures of all the gasses in that mixture

6.11atm = 1.68atm + 3.89atm + Pc

Pc = 6.11atm - (1.68 + 3.89) = 0.54atm

Thus, the partial pressure of C is 0.54atm. The correct option is D.

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Liquid acetaminophen for children is labeled 180 mg 3 ml. The strength expressed as grams per ml is 0.060.

Acetaminophen is a medicine that is used to treat all kind of pains. Headache, menstrual pain, stomach ache, etc. It also used to reduce fever and cold/cough.

Liquid acetaminophen for children is labeled as 180 mg/ 3ml

The 180 mg will be divided by 3 ml

180 mg/ 3ml = 60 mg/ml

The amount will be multiplied by 1 /1000 to get the quantity equal.

60 mg/ml x 1g / 1000 g

60 x 1/ 1000 mg/ml = 0.060

Thus, the strength expressed as grams per ml is 0.060.

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Answer:

1 mole of H2SO4 contains 2 x 6.023 x 10²³ So, 0.1 mole of H2SO4 contains =2 x 6.023 x 10²³ x 0.1

= 1.2 x 10²³atoms of hydrogen

hello there !!

In the Question it's asked that total atoms present in 0.1 mol of H2So4.

so , in the question number of moles is given as 0.1 mole

=> n = 0.1 mole

and total atoms present are = ???

So , in H2So4 molecule there are two hydrogen atoms

=> H2So4 → 2 hydrogen atoms

one mole of H2So4 consist of ;

=> 2 × 6.022 × 10²³

1 mol = 6.022 × 10 ²³ atoms

Therefore, 0.1 mole of H2So4

=> 0.1 × 2 × 6.022 × 10²³ Atoms

=> 0.1 × 2 × 6.022 × 10²³ Atoms=> 12.004 × 10²² Atoms

Answer:

Reactants: Fe₂O₃ and C

Products: Fe and CO₂

Explanation:

The reactants are the molecules that undergo changes in a reaction.

The products are the molecules which are made during a reaction.

The reactants are on the left side of the arrow and the products are on the right side of the arrow. Therefore.....

The chemical reaction:

2 Fe₂O₃ + 3 C -----> 4 Fe + 3 CO₃

Reactants: Fe₂O₃ and C

Products: Fe and CO₂

Platinum has a face-centered cubic crystal structure and a density of 21.5 g/cm^3. The radius of the platinum atom is 139pm.

The radius of the platinum atom can be found by the relation of density and radius of atom.

Platinum has a face-centered cubic (fcc) crystal structure which means that 4 atoms are present in each structure.

Hence no. of atoms, Z=4

The radius of atom can be found out by substitution in the below formula:

Relation of density and radius of atom:

Density, d = Z × M / Nₐ × a³    

∴ where, Z is the no. of atoms = 4                

M is the Molecular mass of platinum = 195 g/mol    

 N is the Avogadro's number = 6 × 10²³ / mol                

 a is the radius of the atom = ?                

d is the density = 21.5 g/cm³

⇒ a³ = Z × M / Nₐ × d

⇒ a³ = 4 × 195 / 6 × 10²³ ×  21.5

⇒ a = 139 × 10⁻¹²m

a = 139pm

Hence, the radius of the platinum atom is 139pm.

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The answer is 139pm

The relationship between density and radius of an atom may be used to calculate the radius of a platinum atom.

Platinum has a face-centred cubic (fcc) crystal structure, which implies that each structure has four atoms.

As a result, the number of atoms is Z=4.

Substitution in the following formula yields the radius of an atom:

Atomic density and radius relationship:

Density,[tex]$d=Z \times M / N_{a} \times a^{3}$[/tex]

[tex]$\therefore$[/tex] where, Z is the no. of atoms =4

[tex]$\mathrm{M}$[/tex] is the Molecular mass of platinum [tex]$=195 \mathrm{~g} / \mathrm{mol}$[/tex]

[tex]$\mathrm{N}$[/tex]is the Avogadro's number [tex]$=6 \times 10^{23} / \mathrm{mol}$[/tex]

a is the radius of the atom = ?

[tex]$\mathrm{d}$[/tex] is the density [tex]$=21.5 \mathrm{~g} / \mathrm{cm}^{3}$[/tex]

[tex]$$\begin{aligned}&\Rightarrow a^{3}=Z \times M / N_{a} \times d \\&\Rightarrow a^{3}=4 \times 195 / 6 \times 10^{23} \times 21.5 \\&\Rightarrow a=139 \times 10^{-12} m \\&a=139 p m\end{aligned}$$[/tex]

What is platinum atom?

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At STP, the volume of water that is produced is 134.4 L.

Now we know that the equation of the reaction is;

2C6H6(g) + 15O2(g) = 12CO2(g) + 6H2O(g)

We can use the stoichiometry of the reaction to determine the volume of the water produced as follows;

2 mole of C6H6 produced 6 moles of water. If 1 mole of water occupies 22.4 L then 6 moles of water will occupy 6 * 22.4 L = 134.4 L

Thus, we can see that at STP, the volume of water that is produced is 134.4 L.

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The sequence of atomic numbers 1, 2, 3, and 4 denotes the periodic table's ordering of following elements.

Series are significant because they offer a possible point of entry. It's possible for a user to merely be aware of the fact that a publication is part of a specific series or to be searching for all publications in that series without being aware of any of the individual titles. The series could potentially be used as a storage and control system.

There are two ways to recognize elements in a series: The elements are in series if there are two and only two connections between them and a single node. When two elements' currents are determined to be similar by KCL at a node, the elements are in series.

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Nitrogen fixation -

What is the organic form of nitrogen?

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The mass of nickel metal deposited on the cathode is 2.004 g.

When an ionic compound is decomposed into its elements by passing a direct electric current using a compound in its liquid form. The process is known as electrolysis.

At the cathode, cations are reduced and at the anode, anions are oxidized.

The main components used in the process of electrolysis are

Current passed through the solution, I = 0.150 A

Time, t = 12.2 hrs = 12.2×60×60 = 43920 sec

Charge, q = It = 0.150 × 43920 = 6588 C

At cathode,

[tex]Ni^{2+}(aq) + 2e^- \rightarrow Ni(s)[/tex]

Nickel metal deposited by (2×96487 C) = 58.7g

Nickel metal deposited by 6588 C = [tex]\frac{58.7 \times 6588 }{2\times96487}[/tex] = 2.004 g

Hence, The mass of nickel metal deposited on the cathode is 2.004 g.

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The freezing point of benzene is 14.08°C.

The temperature at which the liquid and solid states of the substance are in equilibrium at atmospheric pressure.

Calculation

The equation which give relation between freezing point depletion and molality is,

[tex]\Delta T_{f} = K_{f} \times m[/tex]

where,

[tex]\Delta T_{f}[/tex] = change in the freezing point of the solvent.

[tex]K_{f}[/tex] of benzene = 5.12°C/m (given)

M is molality of the solution = 2.75 M

Now, after putting the value in above formula we get

[tex]\Delta T_{f} = K_{f} \times m[/tex]

[tex]\Delta T_{f} = 5.12 \times 2.75[/tex]

       = 14.08°C

Thus from the above conclusion we can say that The freezing point of benzene is 14.08°C.

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Answer:

-8.58

Okay, im having trouble with the question too and the answer i types was wrong, so i went to omnicalculator instead and got this answer which was right. :')

The amount of barium ions that must be present in order for the salt to precipitate is 0.245 M.

A solution's solubility product is the result of raising each ion's concentration to the power of its stoichiometric ratio. It is portrayed as

A combination of 1 barium ion and 2 fluoride ions results in the ionic compound known as barium fluoride.

The following equation describes the equilibrium reaction for barium fluoride ionization:

BaF₂ → Ba²⁺ + 2F⁻

Ksp = [Ba²⁺] · [F⁻]²

2.45*[tex]10^{-5}[/tex]= [Ba²⁺] * [tex][1. 00*10^{-2} ]^{2}[/tex]

[Ba²⁺]=0.245 M

As a result, 0.245 M of barium ions must be present in order for the salt to precipitate.

Solubility in chemistry refers to a chemical's capacity to dissolve in another substance, the solvent, to produce a solution. Inability of the solute to create such a solution is the opposite quality, or insolubility. A substance's degree of solubility in a given solvent is often determined by the amount of the solute present in a saturated solution, which is a solution in which no additional solute can be dissolved. The solubility equilibrium between the two compounds is considered to have been reached at this time. If there is no such restriction for a given solute and solvent, the two are referred to as being "miscible in any amounts."

What concentration of the barium ion, ba2 , must be exceeded to precipitate baf2 from a solution that is 1. 00×10−2 m in the fluoride ion, f−? ksp for barium fluoride is 2. 45×10−5

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The 3.4 moles of Ammonia (NH₃) have 2.0475 x 10²⁴ molecules of it.

We know,

The number of moles is given by

[tex]n =\frac{m}{M}[/tex]

The number of molecules is the product of a number of moles and Avogadro's number[tex]N_A[/tex]

Number of molecules of NH₃ = [tex]n \times N_A[/tex]

                                                 = 3.4 x 6.022 x 10²³

                                                 = 2.0475 x 10²⁴ molecules

Hence, 3.4 moles of Ammonia have 2.0475 x 10²⁴ molecules

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According to the iupac convention, alkyl substituents on a hydrocarbon chain should be listed in alphabetical without taking prefixes into name.

A hydrocarbon would be an organic molecule in organic chemistry that is made completely of hydrogen as well as carbon. A good example of group 14 hydrides includes hydrocarbons. In general, hydrocarbons lack color and are hydrophobic. Typically, their faint smells are compared to that of gasoline and lighter fluid.

Therefore, according to the iupac convention, alkyl substituents on a hydrocarbon chain should be listed in alphabetical without taking prefixes into name.

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91.4 grams mass of KCl is required.

Concentration = moles/Volume

2.45M=mol/0.5L

2.45M⋅0.5L=mol

mol=1.225

Convert no. of moles to grams using the atomic mass of K + Cl

1.225mol⋅(39.1+35.5)/gmol

1.225mol⋅74.6g

mol=1.225⋅74.6g = 91.4g

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When nitrous acid (HNO₂) dissociates in water (H₂O), the reaction that best captures this process is:

                HNO₂ (aq.) + H₂O ↔  H₃O⁺ (aq.) + NO₂⁻ (aq.)

How does one know about HNO₂?

Is HNO₂ a basic or an acid?

Acidity is assigned to nitrous acid (HNO₂). Once dissolved in water, it gives out H+ ions. Acid is a chemical that produces H+ ions in a water-based solution or gives the protons to other molecules.

Thus, HNO₂ is acid because it causes a mixture of water to contain H+ ions. In a 10 mM concentration, it possesses a pH of 2.67.

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The number of sugar particles is 7.4 * 10^22 particles.

The mole is used to describe the amount of substance. The idea was first introduced by Professor Avogadro and the number of particles that constitute one mole of a substance was said to be 6.02 * 10^23 particles in a mole.

Thus;

Molar mass of sugar = 342 g/mol

Number of moles of sugar = 42 grams/342 g/mol = 0.123 moles

Now;

If 1 mole of sugar costs 90 cents

0.123 moles of sugar costs 0.123 moles *  90 cents/1 mole

= 11 cents

Now we know that;

1 mole of sugar contains  6.02 * 10^23 particles

0.123 moles of sugar contains 0.123 moles *  6.02 * 10^23 particles / 1 mole

= 7.4 * 10^22 particles

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The nuclear reactor in Japan had an accident in 2011 when it was hit by an earthquake. The reactor exploded and released a great deal of damaging radiation. The energy for the explosion comes from option(a) i.e, The nucleus of an atom.

An explosion is a sudden increase in volume accompanied by a very strong energy release that usually results in the production of high temperatures and the release of high-pressure gases. High explosive detonations produce supersonic explosions that move through shock waves.

The 2011 Tohoku earthquake and tsunami, which occurred on March 11, 2011, and was the most violent earthquake ever recorded in Japan, were the direct causes of the nuclear tragedy. The nuclear power facility was damaged by the strong tsunami that the earthquake caused, which had waves that were 13 to 14 meters high.

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Answer:

3 half lives

Explanation:

5000 * (1/2)^n  = 625           where n = number of half lives

log ( 625/5000) / log(1/2) = n  = 3

5000         2500     1250      625  

The volume is the product of the molar concentration and the moles of the substance. The volume of hydrochloric acid that can be added to the buffer is 0.066 L.

A buffer is a constant solution with a proton or hydrogen ion concentration with an acid, base, or salt dissolved in them.

The chemical reaction between hydrochloric acid and sodium acetate is given as,

HCl + CH₃Coo-Na → CH₃CooH + NaCl

From above the initials moles of acetic acid are given as,

Moles = molarity × volume

= 0.139 M × 0.0346 L

=  0.0048 moles

The initials moles of sodium acetate are given as,

M = 0.182 M × 0.0365 L

= 0.0066 moles

As it is known that the ratio of the buffer capacity is 10 for sodium acetate and acetic acid so,

Moles sodium acetate ÷ Moles Acetic acid = 10

(0.0066 moles + X) ÷ (0.0048 moles - X)  = 10

Here, X is the moles of HCl and is calculated as,

0.0066 moles + X = 0.048 moles - 10X

11 X = 0.048 ÷ 0.0066

11 X = 7.27

X = 0.66 moles  

The volume of 0.100 HCl with 0.66 moles is:

Volume = moles × molarity

= 0.100 × 0.66

= 0.066 L

Therefore, 0.066 L of 0.100 M HCl is required to reach the buffer capacity.

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δg° for the reaction having e° cell = 2.04v. is 393.658kJ.

The lead (Pb) in the lead storage battery act as an anode

A voltaic cell or galvanic cell is an electrochemical cell that uses chemical reactions to produce electrical energy.

Anode where oxidation occurs Cathode where reduction occurs.

Therefore, Pb acts as anode and PbO2 act as a cathode.

Given,

E° cell = 2.04v

Faraday constant= 96485 C/mol

Moles of electron transferred n= 2

∆G = -nFE°

= -2 × 96485 × 2.04

= 393.658kJ

Thus we concluded that the δg° for the reaction having e° cell = 2.04v. is 393.658kJ.

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Acidosis is a disorder in which there is excess acid in the body. This condition can lead to hyperkalemia due to the diffusion of hydrogen ions in the intracellular fluid.

Hyperkalemia is an increased concentration of the fluid potassium level than normal. Though potassium (K) is needed by the body for various functions of the nervous system and muscles their excess can lead to diseases.

It can also be caused by acidosis, where the concentration of the hydrogen ion increases in the intracellular fluid which leads to a large movement of potassium ions toward the extracellular fluid.

Therefore, the condition of acidosis can cause hyperkalemia.

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The Rutherford experiment was used to prove the existence of a positively charged nucleus containing the protons.

The Rutherford experiment was used to prove the existence of a positively charged nucleus..

Alpha particles passed mostly undeflected through a aluminum foil.

The part of the foil where the alpha particles were deflected  was the positively charged nucleus where most of the mass of the atom was concentrated.

In conclusion, the Rutherford experiment proved the existence of a positively charged nucleus.

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Answer:  

It won't let me type this for some reason but here it is.