Question 1

Which of the following processes is a chemical change, and why?

I. Souring of milk
II. Melting of silver
III. Digestion of food
IV. Burning of coal
V. Condensation of steam

Accepted Answer

I, III, and IV, because all involve changes in chemical composition.

Question 2

Which of the following are heterogeneous mixtures?

I. Sugar
II. Sugar dissolved in water
III. An aqueous suspension of magnesium hydroxide (milk of magnesia)
IV. Samples of nitrogen and oxygen in the same container
V. Samples of argon and iron in the same container

Accepted Answer

III and V

Question 3

How many significant figures are in the number 0.04309?

Accepted Answer

4

Question 4

Convert 25 feet to millimeters. (1 ft = 12 in, 1 in = 2.54 cm, 1 cm = 10 mm)

Accepted Answer

$$7.6 	imes 10^3$ mm

Question 5

A sample of caffeine is 49.47% carbon by mass. What is the mass of carbon in 37.1 g of caffeine?

Accepted Answer

18.4 g

Question 6

The specific gravity of ethyl chloride is 1.37 at $$10^\circC. $$What is the mass of 47.4 mL of the liquid? (Assume density of water = 1.00 g/mL)

Accepted Answer

64.9 g

Question 7

Methane, $$\mathrm{CH_4$}$$, boils at $$-162^\circC. $$What is the boiling point in $$^\circF$$? (Use $$^\circF$$ = $$^\circC$$ $$	imes \frac{9}{5} + 32)$$

Accepted Answer

$$-260^\circF$$

Question 8

How many joules of heat are absorbed by 15.0 g of Al if it is heated from $$20.0^\circC to$$ $$60.0^\circC$$? (Specific heat of Al = 0.900 J/g$$\cdot^\circC)$$

Accepted Answer

540 J

Question 9

Which of the following ions is incorrectly named or classified?

Accepted Answer

nitrite / $$\mathrm{NO_3$^-} / $$polyatomic / anion

Question 10

Which name/formula pair is NOT correctly matched?

Accepted Answer

sodium sulfate / $$\mathrm{Na_2SO_3}$$

Question 11

Calculate the mass of one bromine atom. (Atomic mass of Br = 79.90 g/mol, $$N_A = 6.022 	imes 10$$^{23}$$ mol$$^{-1}$$)

Accepted Answer

$$1.327 	imes 10$$^{-22}$$ g

Question 12

How many grams of $$\mathrm{$$CaCl_2$$}$$ equal 4.26 moles of $$\mathrm{$$CaCl_2$$}$$? (Molar mass $$\mathrm{$$CaCl_2$$} = 110.98 g/$$mol)

Accepted Answer

473 g

Question 13

Calculate the percent by mass of nitrogen in ammonium carbonate, $$(NH_4$)_2CO_3. ($$Molar mass N = 14.01 g/mol, $$(NH_4$)_2CO_3 = 96.09 g/$$mol)

Accepted Answer

29.2%

Question 14

A 4.628-g sample of an oxide of iron contains 3.348 g of iron and 1.280 g of oxygen. What is the simplest formula for this compound?

Accepted Answer

Fe3O4

Question 15

A compound contains, by mass, 87.5% nitrogen and 12.5% hydrogen. Its molecular weight is found to be 32 g/mol. What is its molecular formula?

Accepted Answer

N2H4

Question 16

What mass of hematite, $$\mathrm{Fe_2O_3}$$, would contain 24.0 kg of iron? (Molar mass Fe = 55.85 g/mol, $$\mathrm{Fe_2O_3} = 159.7 g/$$mol)

Accepted Answer

34.3 kg

Question 17

A chemical bottle containing $$\mathrm{K_2Cr_2O_7} is 98.7$$% pure. What mass of Cr is present in 350 g of this chemical? (Molar mass Cr = 52.00 g/mol, $$\mathrm{K_2Cr_2O_7} = 294.2 g/$$mol)

Accepted Answer

122 g

Question 18

Which of the following Lewis dot structures correctly represents H$$_2S$$?

Accepted Answer

Image 3

Question 19

Which of the following Lewis dot structures correctly represents H$$_2CO$_3$$?

Accepted Answer

Image 8

General Chemistry Final Exam Review: Lewis Structures and Molecular Geometry

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