Q: Convert 12.56 in to centimeters. (Recall that 1 inch = 2.54 cm.)

$$12.56 \times 2.54 = 31.87\ \text{cm}$$

Q: Which of the following is the balanced equation for the reaction of potassium hydroxide with sulfuric acid?

$$2\text{KOH} + \text{H}_2\text{SO}_4 \rightarrow 2\text{H}_2\text{O} + \text{K}_2\text{SO}_4$$

Q: What is the percent yield if 18.4 g of $$\text{C}_6\text{H}_6$$ reacts with excess $$\text{Cl}_2 to $$produce 15.4 g of $$\text{C}_6\text{H}_5\text{Cl}$$? (Theoretical yield is 20.0 g.)

$$\frac{15.4}{20.0} \times 100 = 77\%$$

Q: A balloon is filled with 1.00 L helium at 25°C and 1.00 atm. If the pressure is reduced to 0.200 atm at constant temperature, what is the new volume?

$$V_2$$ = \frac{P_1V_1}{$$P_2$$} = \frac{1.00 \times 1.00}{0.200} = 5.00\ \text{L}$$

Q: Which of the following is a double replacement reaction?

$$\text{HCl} + \text{Ca(OH)}_2 \rightarrow \text{CaCl}_2 + 2\text{H}_2\text{O}$$

Q: What is the percent composition by mass of oxygen in $$\text{Ca}_3(\text{PO}_4)_2$$? (Molar mass = 310 g/mol)

$$\frac{8 \times 16}{310} \times 100 = 41.3\%$$

Q: A person accidentally swallows a drop of liquid oxygen ($$\text{O}_2$$), which has a density of 1.40 g/mL. Assuming the drop has a mass of 0.050 g, what volume of gas ($$\text{O}_2) $$will be produced in the person's stomach at body temperature (37°C) and pressure (1.00 atm)? (Use $$R = 0.0821\ \text{L} \cdot \text{atm} / \text{mol} \cdot \text{K}$$, molar mass $$= 32.0\ \text{g/mol})$$

$$V = \frac{nRT}{P} = \frac{(0.050/32.0) \times 0.0821 \times 310}{1.00} = 0.040\ \text{L}$$

Question 1

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture in which the composition is uniform throughout, such as saltwater.

Question 2

Which of the following is an example of a chemical change?

Accepted Answer

Burning magnesium ribbon in air to form magnesium oxide.

Question 3

How many significant figures are in the measurement 0.003050 kg?

Accepted Answer

4

Question 4

Convert 12.56 in to centimeters. (Recall that 1 inch = 2.54 cm.)

Accepted Answer

$$12.56 	imes 2.54 = 31.87\ 	ext{cm}$$

Question 5

A sample contains 77.6% chlorine, 6.7% hydrogen, and the rest is oxygen. The molar mass of the substance is 36.5 g/mol. What is its molecular formula?

Accepted Answer

$$	ext{HCl}$$

Question 6

Which scientist is credited with discovering the nucleus using the gold foil experiment?

Accepted Answer

Rutherford

Question 7

How many protons, neutrons, and electrons are in an atom of $$^{40}_{19}	ext{K}$$?

Accepted Answer

19 protons, 21 neutrons, 19 electrons

Question 8

What is the correct formula for the compound formed by aluminum and fluorine?

Accepted Answer

$$	ext{AlF}_3$$

Question 9

Which of the following is the balanced equation for the reaction of potassium hydroxide with sulfuric acid?

Accepted Answer

$$2	ext{KOH} + 	ext{H}_2	ext{SO}_4 ightarrow 2	ext{H}_2	ext{O} + 	ext{K}_2	ext{SO}_4$$

Question 10

What is the percent yield if 18.4 g of $$	ext{C}_6	ext{H}_6$$ reacts with excess $$	ext{Cl}_2 to $$produce 15.4 g of $$	ext{C}_6	ext{H}_5	ext{Cl}$$? (Theoretical yield is 20.0 g.)

Accepted Answer

$$\frac{15.4}{20.0} 	imes 100 = 77\%$$

Question 11

A balloon is filled with 1.00 L helium at 25°C and 1.00 atm. If the pressure is reduced to 0.200 atm at constant temperature, what is the new volume?

Accepted Answer

$$V_2$$ = \frac{P_1V_1}{$$P_2$$} = \frac{1.00 	imes 1.00}{0.200} = 5.00\ 	ext{L}$$

Question 12

Which of the following is a double replacement reaction?

Accepted Answer

$$	ext{HCl} + 	ext{Ca(OH)}_2 ightarrow 	ext{CaCl}_2 + 2	ext{H}_2	ext{O}$$

Question 13

What is the percent composition by mass of oxygen in $$	ext{Ca}_3(	ext{PO}_4)_2$$? (Molar mass = 310 g/mol)

Accepted Answer

$$\frac{8 	imes 16}{310} 	imes 100 = 41.3\%$$

Question 14

Which of the following is the correct isotope symbol for an ion of chlorine-36 with a -1 charge?

Accepted Answer

$$^{36}_{17}	ext{Cl}^-$$

Question 15

A person accidentally swallows a drop of liquid oxygen ($$	ext{O}_2$$), which has a density of 1.40 g/mL. Assuming the drop has a mass of 0.050 g, what volume of gas ($$	ext{O}_2) $$will be produced in the person's stomach at body temperature (37°C) and pressure (1.00 atm)? (Use $$R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K}$$, molar mass $$= 32.0\ 	ext{g/mol})$$

Accepted Answer

$$V = \frac{nRT}{P} = \frac{(0.050/32.0) 	imes 0.0821 	imes 310}{1.00} = 0.040\ 	ext{L}$$

Question 16

Which of the following is the correct formula for magnesium acetate?

Accepted Answer

$$	ext{Mg(C}_2	ext{H}_3	ext{O}_2)_2$$

Question 17

Which of the following best describes the main source of barium hydroxide and potassium permanganate?

Accepted Answer

Both are produced industrially by chemical synthesis from their respective ores.

Question 18

Which of the following is the correct net ionic equation for the reaction of hydrochloric acid with calcium hydroxide?

Accepted Answer

$$2	ext{H}^+ (aq) + 2	ext{OH}^- (aq) ightarrow 2	ext{H}_2	ext{O} (l)$$

Introduction to Chemistry: Comprehensive Midterm Review Study Notes

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