Answers to Practice Exam #1



Chemistry Practice Exam #1

ANSWERS TO PRACTICE EXAM

1)

Do the following conversions:

|a) 54.2 cm3 to in3 |b) 2.734 x 10-2 nm to cm |

|(1 in = 2.54 cm) | |

| |[pic] |

|[pic] | |

| | |

| | |

| | |

|c) 0.87 g/mL to lb/quart |d) 8.6542 x 107 mg to kg |

|(1 lb = 453.6 g; 1 quart = 0.946 L) | |

| |[pic] |

|[pic] | |

| | |

| | |

|e) 2.867 x 10-9 L to μL | |

| | |

|[pic] | |

| | |

| | |

| | |

| | |

2)

Perform the following mathematical operations and express the results to the correct number of significant figures:

|a) 7.8132 + 0.6 + 18.24 |b) (1.34 x 10-3)x(9.1 x 10-6) |

| | |

|= 26.7 |= 1.2 x 10-8 |

| | |

| | |

| | |

| | |

| | |

| | |

| | |

| | |

| | |

3)

Answer the following True or False:

a) The identity of an atom is determined by the number of electrons it has.

F

b) Copper (II) chloride is an ionic compound

T

c) Different isotopes of a given element have different masses.

T

d) The melting of ice is an example of a physical change.

T

e) Density is an example of a physical property of a substance.

T

4)

[pic]has: Answer is: e)

a) 27 protons, 27 electrons, 59 neutrons

b) 22 protons, 27 electrons, 37 neutrons

c) 27 protons, 27 electrons, 32 neutrons

d) 27 protons, 30 electrons, 32 neutrons

e) 27 protons, 24 electrons, 32 neutrons

5)

Give the formulas of the following compounds:

|a) Lithium oxide |b) Dinitrogen tetroxide |

| | |

|Li2O |N2O4 |

| | |

| | |

| | |

|c) Iron (III) hydroxide |d) Aluminum sulfate |

| | |

|Fe(OH)3 |Al2(SO4)3 |

| | |

| | |

| | |

|e) Chloric acid | |

| | |

|HClO3 | |

| | |

| | |

| | |

6)

Give the names of the following compounds:

|a) Na2SO4 |b) CuS |

| | |

|Sodium sulfate |Copper (II) sulfide |

| | |

| | |

| | |

|c) SO2 |d) (NH4)2CrO4 |

| | |

|Sulfur dioxide |Ammonium chromate |

| | |

| | |

| | |

|e) Hydrobromic acid | |

| | |

|HBr | |

| | |

| | |

| | |

7)

a) Gallium has two naturally occurring isotopes, 69Ga (with a mass of 68.9256 amu and a natural abundance of 60.11%) and 71Ga (with a mass of 70.9247 amu and a natural abundance of 39.89%).

Calculate the average atomic mass of gallium, showing all your work.

68.9256 amu·0.6011 + 70.9247 amu·0.3989 = 69.72 amu

b) If 1 gram is 6.022 x 1023 atomic mass units (amu), calculate the mass in grams of one atom of 69Ga.

[pic]

8)

Balance the following chemical equations:

|a) HI + As2S3 ( AsI3 + H2S |b) Fe + O2 ( Fe2O3 |

| | |

|6HI + As2S3 ( 2AsI3 + 3H2S |4Fe + 3O2 ( 2Fe2O3 |

| | |

| | |

| | |

| | |

| | |

| | |

|c) HBr + KOH ( KBr + H2O |d) Cs + H2O ( CsOH + H2 |

| | |

|HBr + KOH ( KBr + H2O |2Cs + 2H2O ( 2CsOH + H2 |

|Balanced as is | |

| | |

| | |

| | |

| | |

| | |

| | |

|e) C2H6O + O2 ( CO2 + H2O | |

| | |

|C2H6O + 3O2 ( 2CO2 + 3H2O | |

| | |

| | |

| | |

| | |

| | |

| | |

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download