Chemistry 2015-2016
Stoichiometry Practice
Name:
Date:
Per:
Directions: Remember you need a balanced chemical reaction before you begin. Also, if your starting
chemical is not already in units of moles, convert it into moles first before you use the mole-to-mole ratio!
Use the example to help guide you. Report all answers to the correct number of significant figures
Example: What mass of NH3 will react with 29.1 grams of O2 gas according to the following unbalanced
equation: NH3 + O2 → N2 + H2O?
Balance: 4NH3 + 3O2 → 2N2 + 6H2O
Plan: grams O2 → moles O2 → Moles NH3 → Grams NH3
Solve:
1 𝑚𝑜𝑙𝑒 𝑂2
4 𝑚𝑜𝑙𝑒𝑠 𝑁𝐻3 17.034 𝑔𝑟𝑎𝑚𝑠 𝑁𝐻3
29.1 𝑔𝑟𝑎𝑚𝑠 𝑂2 ∗
∗
∗
= 20.7 𝑔𝑟𝑎𝑚𝑠 𝑁𝐻3
32 𝑔𝑟𝑎𝑚𝑠 𝑂2 3 𝑚𝑜𝑙𝑒𝑠 𝑂2
1 𝑚𝑜𝑙𝑒 𝑁𝐻3
1. Aluminum reacts with oxygen in a synthesis reaction. What mass of O2 gas will react with 8.44
moles of Al?
2. Iron and water react to form hydrogen gas and iron (III) oxide. What mass of Fe2O3 form when
7.16 grams of H2 forms?
3. Aluminum and hydrogen chloride react. How many moles of H2 will form when 27.5 grams of
AlCl3 forms?
4. Using the following unbalanced equation:
NaOH + H2SO4 
H2O + Na2SO4
How many grams of sodium sulfate will be formed if you start with 200 grams of sodium hydroxide
and you have an excess of sulfuric acid?
5. Using the following unbalanced equation:
Pb(SO4)2 + LiNO3  Pb(NO3)4 + Li2SO4
How many grams of lithium nitrate will be needed to make 250 grams of lithium sulfate, assuming
that you have an adequate amount of lead (IV) sulfate to do the reaction?
6. Silver sulfide (Ag2S) is the common tarnish on silver objects. What weight of silver sulfide can be
made from 123 g of hydrogen sulfide (H2S) obtained from a rotten egg? The reaction of formation
of silver sulfide is given below:
Ag(s) + H2S(g) + O2(g) → Ag2S(s) + H2O(l)
7. A somewhat antiquated method for preparing chlorine gas involves heating hydrochloric acid
with pyrolusite (manganese dioxide), a common manganese ore. (Reaction given below.) How
many kg of HCl react with 5.69 kg of manganese dioxide? (HINT – 1000 grams = 1 kilogram)
HCl(aq) + MnO2(s) → H2O(l) + MnCl2 (aq) + Cl2(g)
8. Molten iron and carbon monoxide are produced in a blast furnace by the reaction of iron(III) oxide
and coke (pure carbon). If 25.0 kilograms of pure Fe2O3 is used, how many kilograms of iron can
be produced? The reaction is: iron (III) oxide and carbon react to form iron and carbon monoxide
(CO).
9. What mass of water will form when 35.5 grams of oxygen react according to the equation:
ammonia (NH3) reacts with oxygen to produce nitrogen and water
10. What mass of sodium chloride will form when 3.2 moles of sodium chlorate form according to the
equation? sodium hypochlorite reacts to form sodium chloride and sodium chlorate
11. How many molecules of hydrogen fluoride must react to form 256 grams of water according to the
equation? silicon dioxide reacts with hydrogen fluoride to form water and silicon tetrafluoride (SiF4)