Review Package #2

Percentage Composition, Empirical and Molecular Formulae:

1. Write the empirical formula for each of the following compounds.

a) P4O10 ___________________________
b) Mg2Cl4 ___________________________
c) Pb2(CO3)4 ___________________________
d) N 2O 2 ___________________________

2. Calculate the percentage composition by mass of each of the following

compounds. a) CO2 b) C4H8O

3. Calculate the percentage composition of the bold species in each of the following
compounds. a) Cu(NO3)2 b) NaSCN · 5H2O

4. a) A compound has the following composition: 24.24% C, 4.04% H and 71.72% Cl. What
is the empirical formula of the compound?

b) If the molecular mass of this compound is 99.5 g/mol, what is the molecular formula?

5. The molar mass of a compound is 58 g/mol. What is the molecular formula of the
compound if the empirical formula is C2H5?
Molarity Calculations:

1. If a 4.50g sample of solid NaOH is dissolved to make 0.500L of solution, what is the
molarity of the solution?

2. How many grams of Na2CO3 would be required to produce 400.0mL of 0.600M Na2CO3?

3. If 75.7g of Magnesium chloride are mixed with sufficient water to make a 0.885M
solution, what is the volume of the solution?

4. How many mL of 16.4 M H2SO4 are needed to prepare 755mL of 0.25M H2SO4?

Chemical Reactions and Equations:

1. Balance and classify the following chemical reactions. Type of Reaction

a) ___KNO3 → ___KNO2 + ___O2 ________________________

b) ___CaC2 + ___O2 → ___Ca + ___CO2 ________________________

c) ___C5H12 + ___O2 → ___CO2 + ___H2O ________________________

d) ___K2SO4 + ___BaCl2 → ___KCl + ___BaSO4 ________________________

e) ___KOH + ___H2SO4 → ___K2SO4 + ___H2O

________________________

f) ___Ca(OH)2 + ___NH4Cl → ___NH4OH + ___CaCl2

________________________
g) ___C4H9S + ___O2 → ___CO2 + ___SO2 + ___H2O
________________________

h) ___C15H30 + ___O2 → ___CO2 + ___H2O ________________________

i) ___BN + ___F2 → ___BF3 + ___N2 ________________________

j) ___Na + ___ZnI2 → ___NaI + ___Zn

________________________

2. Classify, complete AND balance the following chemical equations. Type of Reaction

a) ___Ni(s) + ___Cu(NO3)2(aq) → ________________________

b) ___Fe (II) (s) + ___O2(g) →

________________________

c) ___NaCl(s) → ________________________

d) ___ H2SO4(aq) + ___NaOH(aq) → ________________________

e) ___C4H10(l) + ___O2(g) →
________________________

f) ___Ag(s) + ___Cl2(g) → ________________________

g) ___Cl2(g) + ___KI(s) → ________________________

h) ___Fe (III)(s) + ___AgCl(aq) → ________________________

i) ___AgNO3(aq) + ___BaCl2(aq) → ________________________

j) ___BaCO3(aq) + ___Sr(OH)2(aq) →
________________________

k) ___C2H5OH(l) + ___O2(g) → ________________________

l) ___HNO3(aq) + ___KOH(aq) → _______________________
3. Write a balanced chemical equation for each of the following, and classify each as
synthesis, decomposition, single replacement, double replacement, neutralization or
combustion.

a) potassium sulphate is mixed with cobalt (III) nitrate

b) liquid propanol (C3H7OH) is burned in air

c) ammonium nitrate is decomposed into it’s elements

d) a piece of zinc is placed in a test-tube containing a solution of silver nitrate

e) bromine reacts with sodium iodide

f) bromine reacts with aluminum

g) rubidium reacts with chlorine gas

h) hydrochloric acid reacts with strontium hydroxide

Energy of Reactions:
1. Define ENDOTHERMIC and EXOTHERMIC reactions.

Endothermic:

Exothermic:
2. Classify the following reactions as either endothermic or exothermic.
a) 2C + O2 → 2CO2 + energy ________________________
b) N2O4 + energy → N2 + 2O2 ________________________

c) AB + C → CB + A + 56.9kJ ________________________
d) AB + CD → AD + BC ΔH = -256.4kJ ________________________

Stoichiometry:

1. Ammonia combines with oxygen gas in the following reaction:

4 NH3 + 5O2 → 6H2O + 4NO

b) How many moles of NH3 are needed to combine with 3.57 moles of O2 gas?

c) If 1.5 grams of NO is produced in the above reaction, how many grams of NH 3 were
reacted?

2. 3Na2CO3 + 2FeCl3 → 6NaCl + Fe2(CO)3

a) How many grams of NaCl will be produced from the reaction of 0.080moles of Na 2CO3
with excess FeCl3?

b) How many grams of FeCl3 would be needed to react with 4.2g of Na2CO3?
3. 3Mg + 2AlCl3 → 3MgCl2 + 2Al

a) How many grams of MgCl2 would be formed if 50.0mL of 0.200M AlCl3 is reacted with
excess Mg?

b) How many mL of 0.150M AlCl3 would be needed to react completely with 2.00g of Mg?

Excess and Limiting Reagents/Percent Yield:

1. 2Fe2S3 + 9O2 → 2Fe2O3 + 6 SO2

In a chemical reaction 6.92g of Fe2S3 is combined with 4.54g of oxygen gas.
a) Which reactant is the LIMITING reagent?

b) How many grams of the EXCESS reactant will be left over after the reaction is
complete?

c) How many grams of Fe2O3 can be formed in this reaction?

2. What mass of P4 will be produced when 41.5g of Ca3(PO4)2, 26.3g of SiO2, and 7.80g of C
are reacted according to the following balanced equation?
2 Ca3(PO4)2 + 6 SiO2 + 10C → P4 + 6CaSiO3 + 10CO

3. 4Al + 3O2 → 2Al2O3

a) How many grams of aluminum oxide, Al2O3, would be expected to form in the reaction
of 15.0g Al with 18.43g of oxygen gas?

b) If the actual yield of Al2O3 produced in the reaction was only 22.4g Al2O3, what would
the PERCENT YIELD of the reaction be?
Extra Stoich Problems:
1. Given the following balanced equation, answer the questions following it:

2NF3(g) + 3H2(g)  N2(g) + 6HF(g)

a) If 5.5 moles of H2 are reacted, how many moles of NF3 will be consumed?

Answer ____________

b) In order to produce 0.47 moles of HF, how many moles of NF3 would be
consumed?

Answer ____________

c) If you needed to produce 180.6 g of N2, how many moles of H2 would you need
to start with?

Answer ____________

d) If you completely react 17.04 g of NF3 , what mass of HF will be produced?

Answer ____________
2. Given the following balanced equation, answer the questions following it:

HBrO3 + 5 HBr  3 H2O(l) + 3 Br2(g)

a) If 3.56 moles of HBr are reacted, how many Litres of Br2 will be formed at STP?

Answer ______________________

b) In order to produce 3.311 x 1024 molecules of Br2, what mass of HBr is needed?

Answer ______________________

3. Given the following balanced chemical equation, answer the question below it.

MgCO3 (s) + 2HCl (aq)  CO2 (g) + H 2O (l) + MgCl2(aq)

a) What mass of MgCO3 will react completely with 15.0 mL of 1.5 M HCl?

Answer _______________________

b) Calculate the volume of 2.0 M HCl which would be needed to react completely
with 37.935 grams of magnesium carbonate.

Answer _______________________
4. Given the following balanced equation, answer the questions below it.

Ba(OH)2(aq) + 2 HNO3(aq)  2 H2O(l) + Ba(NO3)2

a) In a titration, 18.20 mL of 0.300 M Ba(OH)2 is required to react completely with

a 25.0 mL sample of a solution of HNO3. Find the [HNO3].

Answer _______________________

b) In a titration, 11.06 mL of 0.200 M HNO3 is required to react completely with

a sample of 0.250M Ba(OH)2 . Find the volume of the Ba(OH)2 sample.

Answer _______________________

5. Given the following balanced equation, answer the questions below it.

3 Cu(s) + 8HNO3(l)  3 Cu(NO3)2(aq) + 2NO(g) + 4 H2O(l)

a) If 317.5 grams of Cu are placed into 756.0 grams of HNO3, determine which
reactant is in excess.

Answer _______________________

b) If the reaction in (a) is carried out, what mass of NO will be formed?

Answer _______________________
6. Given the balanced equation: 2BN + 3F2  2BF3 + N2 ,

When 161.2 grams of BN are added to an excess of F2, a reaction occurs in which
326.118 grams of BF3 are formed.

a) Calculate the theoretical yield of BF3 in grams.

Answer _______________________

b) Calculate the percentage yield of BF3.

Answer _______________________

7. When reacting NH3 with O2 according to the reaction:

4 NH3 + 5 O2  4 NO + 6 H2O

Using 163.2 grams of NH3 with an excess of O2 produces a 67% yield of NO.

a) Calculate the theoretical yield of NO in grams.

Answer _______________________

b) Calculate the actual yield of NO in grams.

Answer _______________________