Q: Which equation correctly represents the calculation of percent yield in a chemical reaction?

$$\text{Percent Yield} = \frac{\text{Actual Yield}}{\text{Theoretical Yield}} \times 100\%$$

Question 1

Which of the following best describes the scientific method as applied in chemistry?

Accepted Answer

A systematic approach involving observation, hypothesis formation, experimentation, and theory development.

Question 2

A student measures the mass of a sample three times and gets values of 5.12 g, 5.13 g, and 5.11 g. The true mass is 5.50 g. Which statement best describes the measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 3

Which of the following is a chemical property?

Accepted Answer

Reactivity with oxygen

Question 4

Which equation correctly represents the calculation of percent yield in a chemical reaction?

Accepted Answer

$$	ext{Percent Yield} = \frac{	ext{Actual Yield}}{	ext{Theoretical Yield}} 	imes 100\%$$

Question 5

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 6

Which of the following best describes an ionic compound?

Accepted Answer

A compound formed by the transfer of electrons from a metal to a nonmetal.

Question 7

Which of the following is the correct balanced equation for the combustion of methane ($$\mathrm{CH}_4) in $$oxygen?

Accepted Answer

$$\mathrm{CH}_4 + 2\mathrm{O}_2 \rightarrow \mathrm{CO}_2 + 2\mathrm{H}_2\mathrm{O}$$

Question 8

A solution is prepared by dissolving 5.00 g of NaCl in enough water to make 250.0 mL of solution. What is the molarity of the solution? ($$\mathrm{NaCl}$$ molar mass = 58.44 g/mol)

Accepted Answer

$$0.342\ \mathrm{M}$$

Question 9

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

Accepted Answer

Elements are arranged in order of increasing atomic number.

Question 10

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of silver nitrate and sodium chloride?

Accepted Answer

$$\mathrm{Ag}^+ (aq) + \mathrm{Cl}^- (aq) \rightarrow \mathrm{AgCl} (s)$$

Question 11

A gas occupies 10.0 L at 2.00 atm and 300 K. What volume will it occupy at 1.00 atm and 300 K? (Assume ideal gas behavior.)

Accepted Answer

$$20.0\ \mathrm{L}$$

Question 12

Which of the following best describes the first law of thermodynamics?

Accepted Answer

Energy is conserved; it can be transferred or transformed but not created or destroyed.

Question 13

Which of the following electron configurations represents a noble gas?

Accepted Answer

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

Question 14

Which of the following molecules is polar?

Accepted Answer

$$\mathrm{H}_2\mathrm{O}$$

Question 15

Which of the following intermolecular forces is the strongest?

Accepted Answer

Hydrogen bonding

Question 16

A sample of gas has a mass of 2.00 g and occupies 1.00 L at 1.00 atm and 273 K. What is the molar mass of the gas? (Use $$R = 0.0821\ \mathrm{L\ atm\ $$mol^{-1}$$\ K$$^{-1}$$})$$

Accepted Answer

$$44.6\ \mathrm{g/mol}$$

Question 17

Which of the following statements about acids and bases is correct according to the Brønsted-Lowry definition?

Accepted Answer

An acid is a substance that donates a proton ($$\mathrm{H}^+).$$

Question 18

Which of the following best explains why water has a high boiling point compared to other group 16 hydrides?

Accepted Answer

Water forms strong hydrogen bonds between molecules.

Question 19

Which of the following is the correct formula for calculating the density of a gas using the ideal gas law?

Accepted Answer

$$\rho = \frac{PM}{RT}$$

Question 20

Which of the following is an example of a redox reaction?

Accepted Answer

$$2\mathrm{Na} (s) + \mathrm{Cl}_2 (g) \rightarrow 2\mathrm{NaCl} (s)$$

CHEM 120 – University Chemistry I: Course Syllabus and Study Guide

Study Guide - Practice Questions

Study Guide - Flashcards