1) Which of these pairs represent(s) an empirical formula followed by a molecular formula?
I.
II.
III.
O
2
and O
3
NO
2
and N
2
O
4
C
2
H
4
and C
4
H
8
A.
II only B. I and II only C. II and III only D. I, II and III
2) How many hydrogen atoms are present in 0.020 moles of C
2
H
6
?
A.
1.2 x 10 22 B. 7.2 x 10 22 C. 6.0 x 10 23 D. 3.6 x 10 24
3) According to the equation
N
2
+ 3H
2

2 NH
3 what is the maximum number of moles of ammonia that could be made from 0.50 moles of nitrogen and 1.26 moles of hydrogen?
A.
0.42 B. 0.84 C. 1.00 D. 1.76
4) What mass of ammonium nitrate should be weighed out to prepare 5.0 cm 3 of a 0.40 Molar solution?
A.
0.16 g B. 0.40 g C. 32g D. 160 g
5) All of the following statements are consistent with the concept of a mole of substance except
A.
one mole of sodium contains 6.02 x 10 23 atoms.
B.
one mole of carbon–12 atoms has a mass of 12.0 grams.
C.
one mole of chlorine gas contains 6.02 x 10 23 chlorine molecules
D.
one mole of sodium chloride contains 6.02 x 10 23 ions.
6) The balanced equation for the oxidation of ammonia by air is:
4NH
3(g)
+ 5O
2(g)

4NO
(g)
+ 6H
2
O
(g)
How many moles of oxygen gas would be required to react with 20 moles of ammonia?
A.
10 B. 20 C. 25 D. 30
7) What is the mass in grams of one molecule of propanol, C
3
H
7
OH?
(Avogadro’s constant 6.0 x 10 23 mol
–1
)
A.
60 B. 1.0 x 10
–22
C. 1.0 x 10
–23
D. 3.6 x 10 25
8) How many molecules are there in 180g of H
2
O?
A.
6.0 x 10 22 B. 6.0 x 10 23 C. 6.0 x 10 24 D. 6.0 x 10 25
9) Which of the following compounds has the greatest empirical formula mass?
A.
C
6
H
6
B. C
4
H
10
C. C
3
H
6
D. C
2
H
6
10) The number of moles in 500 g of water is approximately
A.
28 B. 9000 C. 1 x 10 25 D. 3 x 10 26
11) Which sample contains the smallest amount of oxygen?
A.
0.3 mol H
2
SO
4
B. 0.6 mol O
3
C. 0.7 mol HCOOH D. 0.8 mol H
2
O

12) A compound that contains only carbon, hydrogen and oxygen has the following percentage by mass: carbon 60%, hydrogen 8%, oxygen 32%
What is a possible molecular formula?
A.
C
5
H
8
O
2
B. C
5
H
4
O C. C
6
HO
3
D. C
7
HO
4
13) When the equation C
4
H
10
+ O
2

CO
2
+ H
2
O is balanced correctly, what is the coefficient for O
2
?
A.
9 B. 13 C. 18 D. 24
14) 6.4 g of copper wire is added to 0.10 dm 3 of 1.0 mol dm
–3
aqueous AgNO
3
to form metallic silver and aqueous copper(II) nitrate. When the reaction is complete
A.
excess copper wire remains.
B.
all the copper wire dissolves and some silver ions are left in solution.
C.
all the copper wire dissolves and no silver ions are left in solution.
D.
the mass of metallic silver formed is equal to the mass of copper wire that reacts.
15) 2.02 g of KNO
3
( M r
= 101) is dissolved in sufficient water to prepare 0.500 dm 3 of solution.
What is the concentration of this solution in mol dm
–3
?
A.
0.02 B. 0.04 C. 0.10 D. 0.20
16) (a) Tin II iodide (SnI
2
) can be prepared by adding a solution of potassium iodide to a solution of tin II chloride (SnCl
2
) and precipitating the insoluble iodide. 2.280 grams of
SnCl
2
were dissolved in 25.0 cm 3 of water and mixed with 10.0 cm 3 of 1.40 M KI solution to precipitate the iodide. i.
Determine which of the reagents is present in excess. ii.
Determine the mass of this reagent remaining at the end of the experiment. iii.
Calculate the maximum mass of tin (II) iodide that could be formed. iv.
In an experiment carried out as described above 1.893 grams of tin (II) iodide were obtained.
Calculate the percentage yield in this experiment.
17) The percentage composition by mass of a hydrocarbon is 85.6% C and 14.4% H.
(a) Calculate the empirical formula of the hydrocarbon.
(b) A 1.00 g sample of the hydrocarbon at a temperature of 0

C and a pressure of 1.01

10 5 Pa has a volume of 0.399 dm 3 .
Calculate the molar mass of the hydrocarbon.
Deduce the molecular formula of the hydrocarbon.
18) 27.82 g of hydrated sodium carbonate crystals, Na
2
CO
3
 x H
2
O, was dissolved in water and made up to
1.000 dm 3 . 25.00 cm 3 of this solution was neutralized by 48.80 cm hydrochloric acid of concentration 0.1000 mol dm
–3
.
3 of
(a) Write an equation for the reaction between sodium carbonate and hydrochloric acid.
(b) Calculate the molar concentration of the sodium carbonate solution neutralized by the hydrochloric acid.
(c) Determine the mass of sodium carbonate present in the 1.000 dm 3 of solution.
(d) Calculate the mass of water present in the hydrated crystals, and find the value of x .