Paper 1: Multiple Choice
10. Which of the following compounds has/have the empirical
formula CH2O?
1. What is the correct formula for zinc sulfate?
I. CH3COOH
II. C6H12O6
III. C12H22O11
A.
C.
PbSO4
PbS
B.
D.
ZnS
ZnSO4
A.
B.
C.
D.
2. A compound with an empirical formula of N2O3 has a
composition of contains 36.8% nitrogen and 63.2%
oxygen by mass. If the molar mass of unknown formula
is 152g/mol, what is the molecular formula?
A. N2O3
C. N3O2
11. Which is a correct definition of the term empirical formula?
B. N4O6
D. N6O2
3. What amount of oxygen, O2, (in moles) contains 1.8×10
molecules?
A. 0.0030.
B. 0.030
C. 0.30
D. 3.0
A.
B.
22
C.
D.
4. Which compound has the empirical formula with the greatest
mass?
A.
C2H6
B. C4H10
C.
C5H10
D. C6H6
5.
When the equation above is balanced, what is the coefficient
for oxygen?
6.
B. 3
D. 5
B. 0.10
C. 20
CH2
C7H10
B.
D.
C3H4
C9H10
3Cu +_HNO3 → _Cu(NO3)2 +_H2O + _NO
What is the coefficient for HNO3 when the equation is
balanced?
9.
4
B. 6
C. 8
1 mol of H2SO4
1 mol of CH3COOH
2 mol of H2O2
2 mol of NH3
13.
A.
B.
C.
D.
Avogadro’s constant has the same value as the number of
molecules in 1 mol of solid iodine.
atoms in 1 mol of chlorine gas.
ions in 1 mol of solid potassium bromide.
protons in 1 mol of helium gas.
15. What is the empirical formula of a compound containing 50%
by mass of element X (Ar = 20) and 50% by mass of element
Y (Ar = 25)?
Copper can react with nitric acid as follows.
A.
A.
B.
C.
D.
14. What is the total number of atoms in 0.20 mol of propanone,
CH3COCH3?
22
A. 1.2×10
23
B. 6.0×10
24
C. 1.2×10
24
D. 6.0×10
D. 80
A hydrocarbon contains 90% by mass of carbon. What is its
empirical formula?
A.
C.
8.
4
What amount (in moles) is present in 2.0 g of sodium
hydroxide, NaOH?
A. 0.050
7.
C.
formula showing the numbers of atoms present in a compound
formula showing the numbers of elements present in a
compound
formula showing the actual numbers of atoms of each element
in a compound
formula showing the simplest ratio of numbers of atoms of
each element in a compound
12. Which sample has the least number of atoms?
__C2H2(g) + __O2(g) → __ CO2(g) + __ H2O(g)
A. 2
II only
III only
I and II only
II and III only
A.
B.
C.
D.
D. 10
XY
X3Y2
X4Y5
X5Y4
The percentage by mass of the elements in a compound is
C = 72%,
H = 12%,
O = 16%.
What is the mole ratio of C:H in the empirical formula of this
compound?
A.1 : 1.
No.
Ans
1
B. 1 : 2.
2
3
C. 1 : 6.
4
D. 6 : 1
5
6
7
8
9
10
11
12
13
14
15
Paper 2 Short Answer Questions
Please show your work for full credit. Marks will be taken off for insufficient rationale and/ or show of work.
16.
Write the formula, molar mass, and percent composition of each element of copper (II) phosphate.
(5)
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17.
Find out the percentage of water by mass in sodium sulfate decahydrate.
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18. The relative molecular mass of aluminum chloride is 267 and its composition by mass is 20.3% Al and 79.7% chlorine.
Determine the empirical and molecular formulas of aluminum chloride.
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(4)
19. What is the mass of 0.45 mol of potassium phosphate?
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(3)
20. How many moles of potassium ions are there in 0.45 mol of potassium phosphate?
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(2)
21. How many carbon atoms are in 0.67 mol of glycerol, C3H5(OH)3?
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(2)
BONUS: (4 points)
After combustion with excess oxygen, a 12.501 g of a petroleum compound produced 38.196 g of carbon dioxide and 18.752 of water.
A previous analysis determined that the compound does not contain oxygen. Establish the empirical formula of the compound.
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