Answers to Midterm Exam 1: 1998

Answers are in bold type


1. (27 marks)

(a) (3 marks)

(i) 1356.0

(ii) 445.7

(iii) 48.027

(b) (3 marks)
K2S

Al2O3

CaCl2

(c) (4 marks)
N2O3

NH4NO3

MnCO3

NaHSO3

(d) (5 marks)
A mole of phosphorus atoms contains 6.022 x 1023atoms.

A mole of P 4 molecules contains 6.022 x 1023molecules.

A mole of P 4 molecules contains 2.409 x 1024atoms.

A mole of phosphorus atoms has a mass of 30.974 grams.

A mole of P4 molecules has a mass of 123.90 grams.

(e) (6 marks) Consider the ion .
The number of neutrons in this ion is 50

The number of protons in this ion is 42.

The mass number is 92 .

The number of electrons is 40 .

The atomic weight of element X is 95.94.

The symbol for element X is Mo


(f) (6 marks) Balanced equations:

2 Fe + 3 Cl2 ---> 2 FeCl3

C6H6O + 7 O2 ---> 6 CO2 + 3 H2O

4 FeS + 7 O2 ---> 2 Fe2O3 + 4 SO2

2. (18 marks)

(a) (5 marks) 3311 grams

(b) (4 marks)

1.00 kg/L

1.00 x 10-3 g/mm3

(c) (3 marks) 40.0 g

(d) (6 marks)

(i) 241.601 g/mol

(ii) 59.6001 % O

3. (10 marks)
38.77 % BaCl2
4. (12 marks)
(a) 213 g fluorine

(b) 303 g SF4

(c) 47.3% yield

5. (15 marks) (a) Organic compounds burn in O2 to give CO2 and water, which can be trapped and weighed.

(b) C2H5O is the empirical formula

6. (6 marks)

(a) After reaction

(b) 4

(c) O2 in excess by 4 molecules

7. (12 marks; 2 marks each)
(i) a

(ii) c

(iii) b

(iv) d

(v) e

(vi) c

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Created September 27, 2000 by M. F. Richardson
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