Q: A car travels at 3060 miles per hour. What is this speed in meters per second? (1 mi = 1.609 km)

$$3060 \times 1.609 \times 10^3$ \div 3600 = 1390 m/s$$

Q: What is the percent by mass of gold (Au) in AuI$$_3$$?

$$\frac{197.0}{197.0 + 3 \times 126.9} \times 100 = 34.10\%$$

Q: What is the molar mass of Potassium Nitrite ($$KNO_2$$)?

$$39.10 + 14.01 + 2 \times 16.00 = 101.11 g/$$mol

Q: What is the percentage of nitrogen, by mass, in calcium nitrate ($$Ca(NO_3$)_2$$)?

$$\frac{2 \times 14.01}{40.08 + 2 \times (14.01 + 3 \times 16.00)} \times 100 = 17.1\%$$

Q: Propane, $$C_3H_8$$, is a common fuel used for cooking and home heating. What mass of $$O_2 is $$consumed in the combustion of 1.00 g of propane?

$$\frac{1.00}{44.10} \times 5 \times 32.00 = 3.63 g$$

Q: An electron has a charge of $$1.602 \times 10$$^{-19}$$ coulombs (C), a wire with a current of 4.0 amperes (C/s) moving through it has a frequency of how many Hz (s$$^{-1}$$)?

$$\frac{4.0}{1.602 \times 10$$^{-19}$$} = 2.5 \times 10$$^{19}$$ Hz

Q: In an alternate universe there are only two naturally occurring isotopes of iron. $$^{56}Fe (64.5$$% abundance) and $$^{62}Fe (35.5$$% abundance). Given this information, what is the atomic weight of iron in this alternate universe?

$$0.645 \times 56 + 0.355 \times 62 = 58.1$$ amu

Question 1

A car travels at 3060 miles per hour. What is this speed in meters per second? (1 mi = 1.609 km)

Accepted Answer

$$3060 	imes 1.609 	imes 10^3$ \div 3600 = 1390 m/s$$

Question 2

What is the percent by mass of gold (Au) in AuI$$_3$$?

Accepted Answer

$$\frac{197.0}{197.0 + 3 	imes 126.9} 	imes 100 = 34.10\%$$

Question 3

Which of the following oxyanions is incorrectly named?

Accepted Answer

IO$$_3^-$$: iodate

Question 4

Which of the following is an incorrect representation for a neutral atom?

Accepted Answer

$$^{18}_{47}Ag$$

Question 5

Which of the following acids is incorrectly named?

Accepted Answer

Perbromic acid, HBrO$$_4$$

Question 6

How many total electrons are there in the chlorite anion?

Accepted Answer

20

Question 7

Which of the following must be present in an ion?

Accepted Answer

An electron

Question 8

What is the molar mass of Potassium Nitrite ($$KNO_2$$)?

Accepted Answer

$$39.10 + 14.01 + 2 	imes 16.00 = 101.11 g/$$mol

Question 9

For the reaction: $$CH_4(g$$) + $$Br_2(l$$) \rightarrow $$CBr_4(s) + $$HBr(g)$$, what is the coefficient for bromine (Br_2$) when the reaction is balanced?

Accepted Answer

4

Question 10

What is the percentage of nitrogen, by mass, in calcium nitrate ($$Ca(NO_3$)_2$$)?

Accepted Answer

$$\frac{2 	imes 14.01}{40.08 + 2 	imes (14.01 + 3 	imes 16.00)} 	imes 100 = 17.1\%$$

Question 11

Cyclohexane, a commonly used organic solvent, is 85.6% C and 14.4% H by mass with a molar mass of 84.2 g/mol. What is the molecular formula?

Accepted Answer

C$$_6H$_{12}$$

Question 12

In the combustion of the hydrocarbon $$C_3H_8$$, what is the coefficient for $$O_2$$ when the reaction is balanced?

Accepted Answer

5

Question 13

Propane, $$C_3H_8$$, is a common fuel used for cooking and home heating. What mass of $$O_2 is $$consumed in the combustion of 1.00 g of propane?

Accepted Answer

$$\frac{1.00}{44.10} 	imes 5 	imes 32.00 = 3.63 g$$

Question 14

Molten gallium reacts with arsenic to form the semiconductor gallium arsenide, $$GaAs$$, used in light emitting diodes and solar cells: $$Ga(l) + As(s) \rightarrow GaAs(s). If 4.00 g of $$gallium is reacted with 5.50 g of arsenic, how many grams of the excess reactant are left at the end of the reaction?

Accepted Answer

1.50 g As

Question 15

Both titanium and lead have been used as whitening sources for paint. The density of titanium is 4.506 g/cm$$^3$$, the density of lead is 11.34 g/cm$$^3. $$How many times heavier would one expect 2 gallons of lead powder to be compared to 2 gallons of titanium powder?

Accepted Answer

$$\frac{11.34}{4.506} = 2.517$$ times heavier

Question 16

An electron has a charge of $$1.602 	imes 10$$^{-19}$$ coulombs (C), a wire with a current of 4.0 amperes (C/s) moving through it has a frequency of how many Hz (s$$^{-1}$$)?

Accepted Answer

$$\frac{4.0}{1.602 	imes 10$$^{-19}$$} = 2.5 	imes 10$$^{19}$$ Hz

Question 17

In an alternate universe there are only two naturally occurring isotopes of iron. $$^{56}Fe (64.5$$% abundance) and $$^{62}Fe (35.5$$% abundance). Given this information, what is the atomic weight of iron in this alternate universe?

Accepted Answer

$$0.645 	imes 56 + 0.355 	imes 62 = 58.1$$ amu

Question 18

$$^{24}Mg is $$the most abundant isotope of Magnesium with 78.99% abundance. There are two additional naturally occurring Magnesium isotopes $$^{25}Mg $$and $$^{26}Mg. $$What is the percent abundance of $$^{25}Mg$$? Assume the atomic masses are the mass numbers of each isotope.

Accepted Answer

21.0%

Question 19

If 6.0 grams of Beryllium Fluoride is reacted with excess Aluminum Phosphate to give Beryllium Phosphate and AlF$$_3$$, how many grams of Beryllium Phosphate are produced?

Accepted Answer

7.1 grams

Question 20

How many moles are in 12.0 g of LiCl?

Accepted Answer

$$\frac{12.0}{42.4} = 0.283$$ moles

General Chemistry Exam Study Guide: Key Concepts and Applications

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