Chemistry Practice Problems I

Question 1

Define each of the following as atomic element, molecular element, ionic compound, or molecular compound: Au, Li2SO4, PCl5, NaCl, P4, He, F2, H2O.

Question 2

How many moles (of molecules or formula units) are in each sample?

– 22.2 kg Fe(NO3)2

– 0.2982 g of C8H18

– 114 kg CaO

Question 3

Calculate the mass (in g) of each sample.

– 1.8 x 1025 O3 molecules

– 7.8 x 1019 CCl2F2

– 1 water molecule(s)

 Question 4

Calculate the empirical formula for each of the following flavors based on their elemental mass percent composition.

– nitroglycerin (used medically as a vasodilator to treat hear conditions): C 15.87% H 2.22% N 18.50% O 63.41%

– glucose (a source of energy and metabolic intermediate): C 40.00% H 6.71% O 53.29%

Question 5

Nitric acid is a component of acid rain that forms when gaseous dioxide pollutant reacts with gaseous oxygen and liquid water to form aqueous nitric acid.

Write a balanced chemical equation for this reaction.

Question 6

Write a balanced chemical equation for each if the following.

A- Solid copper reacts with solid sulfur to from solid copper(I) sulfide.

B- Liquid octane reacts with oxygen to form carbon dioxide gas and water vapor.

C- Nitric oxide gas reacts with hydrogen gas to from ammonia gas and water vapor.

D- Gaseous ammonia (NH3) reacts with gaseous oxygen to from gaseous nitrogen monoxide and gaseous water.

Question 7

Balance each of the following chemical equations. Give your answer as coefficients separated by commas.

A- Na2S(aq) + Cu(NO3)2(aq) –> NaNO3(aq) + CuS(s)

B- NH4NO3(aq) –> N2O(g) + H2O(l)

C- HClO3(aq) + HBr(aq) –> HCl(aq) + Br2(g) + H2O(l)

D- MgCO3(aq) + HCl(aq) –> MgCl2 + H2O(l) + CO2(g)

 Question 8

Write a formula based on the name, or a name based on the formula, for each of the following hydrocarbons.

A- CH3CH3

B- Pentane

C- CH3CH2CH2CH2CH2CH3

D- Heptane

Question 9

Calculate how many moles of NH3 from when each quantity of reactant completely reacts. 3 N2H4(l) –> 4 NH3(g) + N2(g)

A- 2.4 mol N2H4

B- 3.85 mol N2H4

C- 65.8 g N2H4

D- 4.84 kg N2H4

 Question 10

For each of the reactions, calculate the mass (in grams) of the product formed when 15.24 g of the underlined reactant completely reacts. Assume that there is more than enough of the other reactant.

A- 2K(s) + Cl2(g) –> 2KCl(s)

B- 2K(s) + Br2(l) –> 2KBr(s)

C- 4Cr(s) + 3O2(g) –> 2Cr2O3(s)

D- 2Sr(s) + O2(g) –> 2SrO(s)

Question 11

For the reaction shown, find the limiting reactant for each of the following initial amounts of reactants.

4Al(s) + 3O2 (s) –> 2Al2O3(s)

A- 1 mol Al, 1 mol O2

B- 4 mol Al, 2.6 mol O2

C- 16 mol Al, 13 mol O2

D- 7.4 mol Al, 6.5 mol O2

Question 12

For the reaction shown, compute the theoretical yield of product (in moles) for each of the following initial amounts of reactants.

Mn(s) + O2(g) –> MnO2(s)

A- 3 mol Mn, 3 mol O2.

B- 4 mol Mn, 9 mol O2.

C- 28.5 mol Mn, 44.8 mol O2.

Question 13

Consider the following reaction: Li2S(aq) + Co(NO3)2(aq) –> 2LiNO3(aq) + CoS(s).

What volume of 0.150 M Li2S solution is required to completely react with 125 mL of 0.150 M Co(NO3)2?

Question 14

Complete and balance each of the following equations. If no reaction occurs, write NO REACTION.

A: Pb(NO3)2(aq) + 2KCl(aq) –>

B: 2NaCl(aq) + Hg2(C2H3O2)2(aq) –>

C: (NH4)2SO4(aq) + CuCl2(aq) –>

D: Al2(SO4)3(aq) + 6AgNO3(aq) –>

Question 15

A- Write balanced complete ionic equation for K2SO4(aq) + CaI2(aq) à CaSO4(s) + KI(aq)

B- Write balanced net ionic equation for K2SO4(aq) + CaI2(aq) à CaSO4(s) + KI(aq)

C- Write balanced complete ionic equation for NH4Cl(aq) + NaOH(aq) à H2O(l) + NH3(g) + NaCl(aq)

D- Write balanced net ionic equation for for NH4Cl(aq) + NaOH(aq) à H2O(l) + NH3(g) + NaCl(aq)

E- Write balanced complete ionic equation for AgNO3(aq) + NaCl(aq) à AgCl(s) + NaNO3(aq)

F- Write balanced net ionic equation for AgNO3(aq) + NaCl(aq) à AgCl(s) + NaNO3(aq)

G- Write balanced complete ionic equation for HC2H3O2(aq) + K2CO3(aq) à H2O(l) + CO2 (g) + KC2H3O2(aq)

H- Write balanced net ionic equation for HC2H3O2(aq) + K2CO3(aq) à H2O(l) + CO2 (g) + KC2H3O2(aq)

Question 16

Complete and balance each of the following equations for gas-evolution reactions.

A: HNO3(aq) + Na2SO3(aq) –>

B: HBr(aq) + NaHCO3(aq) –>

C: HI(aq) + KHSO3(aq) –>

D: (NH4)2SO4(aq) + Ca(OH)2(aq) –>