Q: A student is asked to convert 25.0 grams of NaCl to moles. Given the molar mass of NaCl is 58.44 g/mol, which equation should be used and what is the correct answer?

Use $$\text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}}$$; the answer is $$0.428$$ moles.

Q: Which of the following is the correct formula for calculating the percent composition by mass of an element in a compound?

$$\text{Percent composition} = \frac{\text{mass of element}}{\text{total mass of compound}} \times 100\%$$

Question 1

Which of the following best describes the primary reason for wearing approved lab safety goggles during chemistry laboratory sessions?

Accepted Answer

To prevent chemical splashes from contacting the eyes, reducing the risk of injury.

Question 2

A student is asked to convert 25.0 grams of NaCl to moles. Given the molar mass of NaCl is 58.44 g/mol, which equation should be used and what is the correct answer?

Accepted Answer

Use $$	ext{moles} = \frac{	ext{mass (g)}}{	ext{molar mass (g/mol)}}$$; the answer is $$0.428$$ moles.

Question 3

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 ($$H^+) to $$another substance.

Question 4

Which of the following best explains why the atomic radius decreases across a period in the periodic table?

Accepted Answer

Increasing nuclear charge pulls electrons closer to the nucleus.

Question 5

A patient receives a saline solution containing $$0.90\%$$ NaCl by mass. If the patient receives $$500 mL of $$solution with a density of $$1.00 g/mL$$, how many grams of NaCl did the patient receive?

Accepted Answer

$$4.5$$ grams

Question 6

Which of the following is the correct Lewis structure for $$CO_2$$?

Accepted Answer

O=C=O, with each oxygen having two lone pairs.

Question 7

Which of the following functional groups is present in all amino acids?

Accepted Answer

Both an amine ($$-NH_2$) and a carboxylic acid (-$$COOH$$) group.

Question 8

Which of the following best describes the process of neutralization in acid-base chemistry?

Accepted Answer

An acid reacts with a base to produce water and a salt.

Question 9

A chemical reaction has the following balanced equation: $$2H_2 + O_2$ \rightarrow 2H_2O. If $$you start with $$4$$ moles of $$H_2$$ and $$2$$ moles of $$O_2$$, how many moles of $$H_2O$$ will be produced?

Accepted Answer

$$4$$ moles

Question 10

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

Accepted Answer

Water has a bent molecular shape and an uneven distribution of electron density.

Question 11

Which of the following is the correct formula for calculating the percent composition by mass of an element in a compound?

Accepted Answer

$$	ext{Percent composition} = \frac{	ext{mass of element}}{	ext{total mass of compound}} 	imes 100\%$$

Question 12

Which of the following statements about enzymes is correct?

Accepted Answer

Enzymes are biological catalysts that speed up chemical reactions without being consumed.

Question 13

Which of the following is the correct relationship between pressure and volume for a gas at constant temperature (Boyle's Law)?

Accepted Answer

$$P_1V_1 = P_2V_2$$

Question 14

A solution is prepared by dissolving $$10.0$$ grams of glucose ($$C_6H_{12}O_6$) in enough water to make 500$ mL of solution. What is the molarity of the solution? (Molar mass of glucose = 180.16$ g/mol)

Accepted Answer

$$0.111 M$$

Question 15

Which of the following best describes the role of functional groups in organic chemistry?

Accepted Answer

Functional groups determine the chemical reactivity and properties of organic molecules.

Question 16

Which of the following is the correct formula for calculating the energy change ($$\Delta H) in a $$chemical reaction using Hess's Law?

Accepted Answer

$$\Delta H_{	ext{reaction}} = \sum \Delta H_{	ext{products}} - \sum \Delta H_{	ext{reactants}}$$

Question 17

Which of the following statements about carbohydrates is correct?

Accepted Answer

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen, typically with a $$1:2:1$$ ratio.

Question 18

Which of the following best describes the difference between saturated and unsaturated fatty acids?

Accepted Answer

Saturated fatty acids have no double bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.

Question 19

Which of the following is the correct formula for calculating the pH of a solution given the hydrogen ion concentration $$[H^+]$$?

Accepted Answer

$$pH = -\log_{10}[H^+]$$

CHEM 1104: General, Organic, and Biological Chemistry – Syllabus and Study Guide

Guida di studio - Domande di pratica

Study guide - Flashcard