Unit 3 PRACTICE TEST
Toombs
1.
35.0 g of copper (II) iodide (dissolved to make an aqueous solution) reacts with 39.0 g of
silver nitrate (in aqueous solution).
a) calculate the grams of each product formed
b) state the limiting reagent
c) determine the amount, in grams, by which the other reagent is in excess
d) show your check of the law of conservation of mass
2.
If 4.11 g of Iron are added to 317 mL of Hydrogen Sulphide gas at STP, will both reactants be
totally consumed? What mass of products will we obtain?
3.
Given the reaction: Ca3(PO4)2(s) + SiO2 (s) + C(s) → P4(g) + CaSiO3(s) + CO(g)
What mass of carbon monoxide gas is produced from 4.14 g Ca3(PO4)2 and 1.20 g of SiO2?
Find the mass of CO(g) product formed and the mass of excess reactants.
4.
Define and draw a diagram for
a) exothermic reaction
b) endothermic reaction
In your answer, explain how stoichiometry affects the kJ of energy involved in a reaction.
5.
Calculate the empirical formula for each compound:
a) 7.20% P, 92.8% Br
b) 43.7% Zr, 10.3% B, 46.0% O
6.
a) An unknown sample has 47.08 % C, 6.59 % H, and 46.33 % Cl. What is its empirical
formula?
b) For the example above, if the molar mass of the actual compound is 153 g/mol, what is its
molecular formula?
7.
An unknown compound was found to have a percent composition as follows: 47.0 % potassium,
14.5 % carbon, and 38.5 % oxygen. What is its empirical formula? If the true molar mass of the
compound is 166.22 g/mol, what is its molecular formula?
8.
A 13.4 g sample of a compound contains 5.36 g of carbon, 0.902 g of hydrogen and
7.14 g of oxygen. Determine the empirical formula of the compound.
9.
58.5 g C reacts with hydrogen gas producing 73.0 g ethane. What is the formula of
ethane?
10.
Calculate the theoretical yield of C2H5Cl if 112 g of C2H5OH is reacted with 34.7 g of
PCl3, forming C2H5Cl and H3PO3. If 23.7 g of C2H5Cl is produced, what is the percent yield?
11.
Uranium reacts with Bromine to form Uranium (VI) bromide in a synthesis reaction. If the
reaction starts with 100. g of Uranium and the percent yield of this reaction is 83%, what is the actual
yield of Uranium (VI) bromide?
ANSWER KEY ON WEBSITE! http://blog44.ca/ericatoombs/chem-11-unit-3/
Also go back and thoroughly review (re-do!) all of the worksheets that you have received
during Unit 3.
ANSWER KEY
1. a) 20.6 g Cu(NO3)2 and 51.7 g AgI
b) CuI2 is the limiting reagent
c) 1.70 g AgNO3 excess (note that depending on sig figs, you may have 1.60 g as an answer)
d) 35.0 g + 39.0 g = 51.7 g + 20.6 g + 1.70 g
Another way to show the check: 35.0 + 37.4 = 51.7 + 20.6
2. No, both reactants will NOT be totally consumed.
(In other words, this is limiting and excess reagents problem)
Products formed: 1.25 g FeS and 0.0287 g H2
3. 0.935 g CO formed and 2.07 g of excess Ca3 (PO4)2 remains
4. See your notes!
5. a) PBr5
b) Zr(BO3)2
6. a) C3H5Cl
b) C6H10Cl2
7. empirical: KCO2 and molecular: K2C2O4
8. CH2O
9. C2H6 is ethane
10. 48.6 %
11. 250. g of UBr6
Also go back and thoroughly review (re-do!) all of the worksheets that you have received
during Unit 3 that relate directly to these PRACTICE TEST
questions!