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UNIT 6 TEST - REVIEW

Total questions: 17

Worksheet time: 23mins

Name
Class
Date
1.

How many atoms of chlorine are there in chlorine gas??

a)

1

b)

2

c)

3

d)

4

2.

What is the molar mass of chlorine gas in grams (round to two decimal places)?

a)

35.45 grams

b)

70.90 grams

c)

71 grams

d)

35.5 grams

3.

The sum of the atomic masses of all the atoms in a formula for a covalent compound is the —

a)

real mass

b)

covalent mass

c)

Avogadro mass

d)

molecular mass

4.

What CONVERSION would you use for this problem: Which of the following is the mass in grams of 4.25 x 103 mol of N2?

a)

To go from moles to grams, use: 1 mole = molar mass (in grams)

b)

To go from moles to grams, use: 1 mole = 6.02 x 1023 particles

5.

Which of the following is the mass in grams of 4.25 x 103 mol of N2?

a)

2.35 x 10-4 g

b)

1.52 x 102 g

c)

5.95 x 104 g

d)

1.19 x 105 g

6.

What CONVERSION would you use for this problem: A three (3.00) mole sample of K2S would have how many atoms?

a)

To go from moles to atoms (particles), use: 1 mole = 6.02 x 1023 particles

b)

To go from moles to atoms (particles), use: 1 mole = molar mass (in grams)

7.

A three (3.00) mole sample of K2S would have how many atoms?

a)

2.01 x 1023 atoms

b)

1.21 x 1024 atoms

c)

1.81 x 1024 atoms

d)

3.61 x 1024 atoms

8.

What conversion would you use for this problem: How many atoms of silicon would there be in a sample that contained 4.66 x 1030 grams?

a)

To go from grams to atoms: 1 mole = 6.02 x 1023 particles

b)

To go from grams to atoms: 1 mole = molar mass (in grams)

c)

To go from grams to atoms: This is a TWO STEP problem! First you go from grams to moles: 1 mole = molar mass (in grams); THEN you go from moles to atoms (particles): 1 mole = 6.02 x 1023 particles

d)

This calculation can not be done.

9.

How many atoms of silicon would there be in a sample that contained 4.66 x 1030 grams?

a)

9.99 x 10690 atoms

b)

9.99 x 1052 atoms

c)

1.69 x 10690 atoms

d)

1.69 x 1052 atoms

10.

What is the percent composition of carbon in the compound benzene (C6H6) to two significant figures?

a)

8% carbon

b)

17% carbon

c)

50% carbon

d)

92% carbon

11.

What is the percent composition of the element hydrogen in the compound methane, CH4?

a)

16.0%

b)

25.1%

c)

74.9%

d)

100.0%

12.

Ca3(PO4)2 has a molar mass of 310.174 g/mol. Determine the percent composition of phosphorus to five significant digits.

a)

0.19972% phosphorus

b)

0.2% phosphorus

c)

20% phosphorus

d)

19.972% phosphorus

13.

Is this formula empirical or molecular: P4O10?

a)

empirical

b)

molecular

c)

neither

14.

The molecular formula for phosphorous pentoxide is P4O10. What is its empirical formula?

a)

PO2.5

b)

P0.4O

c)

P2O5

d)

P2O8

15.

Which of these formulas is an example of an empirical formula?

a)

H2O2

b)

NAHCO3

c)

N2H8

d)

P3O9

16.

How many atoms are in a 591 g sample of gold?

a)

3.00 atoms

b)

116,000 atoms

c)

1.81 x 1024 atoms

d)

3.60 x 1025 atoms

17.

Calculate the number of molecules present in 0.20 moles of H2O.

a)

2.4 x 1023 molecules

b)

1.2 x 1023 molecules

c)

2.9 x 1025 molecules

d)

5.1 x 1022 molecules