Q: A student measures the mass of a sample as 12.5 grams and its volume as 5.0 mL. What is the density of the sample?

$$\text{Density} = \frac{12.5\ \text{g}}{5.0\ \text{mL}} = 2.5\ \text{g/mL}$$

Q: How many moles are in 18 grams of water ($$\text{H}_2\text{O}$$)? (Molar mass of $$\text{H}_2\text{O} = 18\ \text{g/mol})$$

$$\frac{18\ \text{g}}{18\ \text{g/mol}} = 1\ \text{mol}$$

Q: Balance the following chemical equation: $$\text{C}_3\text{H}_8 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O}$$

$$\text{C}_3\text{H}_8 + 5\ \text{O}_2 \rightarrow 3\ \text{CO}_2 + 4\ \text{H}_2\text{O}$$

Q: A student needs to convert 250 mL to liters. Which of the following is correct?

$$250\ \text{mL} \times \frac{1\ \text{L}}{1000\ \text{mL}} = 0.25\ \text{L}$$

Q: Which of the following best describes Avogadro’s number?

The number of particles in one mole, $$6.022 \times 10$$^{23}$$

Question 1

Which of the following best describes a chemical change?

Accepted Answer

Iron rusting when exposed to air

Question 2

A student measures the mass of a sample as 12.5 grams and its volume as 5.0 mL. What is the density of the sample?

Accepted Answer

$$	ext{Density} = \frac{12.5\ 	ext{g}}{5.0\ 	ext{mL}} = 2.5\ 	ext{g/mL}$$

Question 3

Which of the following is a correct electron configuration for a neutral sodium atom ($$Z=11$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^1$$

Question 4

Which of the following compounds is ionic?

Accepted Answer

NaCl

Question 5

How many moles are in 18 grams of water ($$	ext{H}_2	ext{O}$$)? (Molar mass of $$	ext{H}_2	ext{O} = 18\ 	ext{g/mol})$$

Accepted Answer

$$\frac{18\ 	ext{g}}{18\ 	ext{g/mol}} = 1\ 	ext{mol}$$

Question 6

Which laboratory safety rule is most important when working with acids?

Accepted Answer

Always add acid to water, not water to acid

Question 7

Which of the following best describes the difference between a physical and a chemical property?

Accepted Answer

A physical property can be observed without changing the substance’s identity, while a chemical property describes how a substance reacts with other substances.

Question 8

A solution is prepared by dissolving 10 grams of NaCl in 100 mL of water. Which term best describes NaCl in this context?

Accepted Answer

Solute

Question 9

Which of the following best explains why water is a polar molecule?

Accepted Answer

Water has a bent shape and an uneven distribution of electrons.

Question 10

Balance the following chemical equation: $$	ext{C}_3	ext{H}_8 + 	ext{O}_2 ightarrow 	ext{CO}_2 + 	ext{H}_2	ext{O}$$

Accepted Answer

$$	ext{C}_3	ext{H}_8 + 5\ 	ext{O}_2 ightarrow 3\ 	ext{CO}_2 + 4\ 	ext{H}_2	ext{O}$$

Question 11

Which of the following is the correct formula for calcium phosphate?

Accepted Answer

$$	ext{Ca}_3(	ext{PO}_4)_2$$

Question 12

A student needs to convert 250 mL to liters. Which of the following is correct?

Accepted Answer

$$250\ 	ext{mL} 	imes \frac{1\ 	ext{L}}{1000\ 	ext{mL}} = 0.25\ 	ext{L}$$

Question 13

Which of the following best describes Avogadro’s number?

Accepted Answer

The number of particles in one mole, $$6.022 	imes 10$$^{23}$$

Question 14

Which of the following is a property of acids?

Accepted Answer

They turn blue litmus paper red

Question 15

A compound contains 40% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula?

Accepted Answer

$$	ext{CH}_2	ext{O}$$

Question 16

Which of the following best explains why salt (NaCl) dissolves in water?

Accepted Answer

The positive and negative ions in NaCl are attracted to the partial charges on water molecules.

Question 17

Which laboratory equipment would you use to accurately measure 25.0 mL of a liquid?

Accepted Answer

A graduated cylinder

Question 18

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 19

A reaction requires 2.0 moles of hydrogen gas ($$	ext{H}_2) $$and excess oxygen gas ($$	ext{O}_2) to $$produce water. How many grams of water are produced? ($$	ext{H}_2 + \frac{1}{2}	ext{O}_2 ightarrow 	ext{H}_2	ext{O}$$, molar mass of $$	ext{H}_2	ext{O} = 18\ 	ext{g/mol})$$

Accepted Answer

$$2.0\ 	ext{mol} 	imes 18\ 	ext{g/mol} = 36\ 	ext{g}$$

Question 20

Which of the following best describes the VSEPR theory?

Accepted Answer

It predicts the shape of molecules based on electron pair repulsion.

CHEM 1020 Introductory Chemistry Syllabus and Course Structure Study Guide

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