Q: Which of the following is the correct setup to calculate the number of moles in 25.0 grams of glucose ($$C_6H_{12}O_6$)? (Molar mass of glucose = 180.16 g/mol)

$$25.0 \ \mathrm{g} \times \dfrac{1 \ \mathrm{mol}}{180.16 \ \mathrm{g}}$$

Question 1

Which of the following best describes the difference between a chemical change and a physical change? Consider the example of boiling water and burning wood.

Accepted Answer

Boiling water is a physical change because the water changes state but not composition, while burning wood is a chemical change because new substances are produced.

Question 2

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

Accepted Answer

The measurements are precise but not accurate.

Question 3

Which of the following is the correct setup to calculate the number of moles in 25.0 grams of glucose ($$C_6H_{12}O_6$)? (Molar mass of glucose = 180.16 g/mol)

Accepted Answer

$$25.0 \ \mathrm{g} 	imes \dfrac{1 \ \mathrm{mol}}{180.16 \ \mathrm{g}}$$

Question 4

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

$$CH_2O$$

Question 5

Which of the following best explains why salt (NaCl) dissolves in water but not in gasoline?

Accepted Answer

Because water is polar and can stabilize the ions, while gasoline is nonpolar and cannot.

Question 6

A student mixes solutions of silver nitrate ($$AgNO_3) $$and sodium chloride ($$NaCl). A $$white precipitate forms. Which equation best represents the reaction?

Accepted Answer

$$AgNO_3 (aq) + $$NaCl (aq) \rightarrow AgCl (s) + $$NaNO_3 (aq$$)$$

Question 7

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

Accepted Answer

Elements in the same group have the same number of valence electrons.

Question 8

A balloon filled with helium gas at 1.00 atm and 300 K has a volume of 2.00 L. If the temperature increases to 400 K at constant pressure, what is the new volume? (Assume ideal gas behavior.)

Accepted Answer

$$2.67 \ \mathrm{L}$$

Question 9

Which of the following best describes the role of a catalyst in a chemical reaction?

Accepted Answer

It lowers the activation energy, increasing the reaction rate.

Question 10

Which of the following is the correct net ionic equation for the reaction between hydrochloric acid ($$HCl) $$and sodium hydroxide ($$NaOH) in $$aqueous solution?

Accepted Answer

$$H^+ (aq) + OH^- (aq) \rightarrow H_2O (l)$$

Question 11

A sample of 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 explains why ice floats on water?

Accepted Answer

Because hydrogen bonding causes ice to have an open structure, making it less dense than liquid water.

Question 13

Which of the following is a correct application of the Law of Conservation of Mass in a chemical reaction?

Accepted Answer

The total mass of reactants equals the total mass of products.

Question 14

Which of the following best describes the difference between an ionic bond and a covalent bond?

Accepted Answer

An ionic bond involves the transfer of electrons, while a covalent bond involves the sharing of electrons.

Question 15

A student needs to prepare 250.0 mL of a 0.100 M $$NaCl$$ solution. How many grams of $$NaCl ($$molar mass = 58.44 g/mol) are required?

Accepted Answer

$$1.46 \ \mathrm{g}$$

Question 16

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

Accepted Answer

$$2H_2 (g) + O_2$ (g) \rightarrow 2H_2O (l)$$

Question 17

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

Accepted Answer

An acid is a proton donor and a base is a proton acceptor.

Question 18

A student titrates 25.0 mL of $$0.200 \ \mathrm{M} \ HCl$$ with $$0.100 \ \mathrm{M} \ NaOH. $$What volume of $$NaOH is $$required to reach the equivalence point?

Accepted Answer

$$50.0 \ \mathrm{mL}$$

Question 19

Which of the following best describes the purpose of using the Kinetic Molecular Theory in chemistry?

Accepted Answer

To describe the motion and behavior of gas particles.

CHEM 131/031 Principles of Chemistry – Syllabus and Study Guide

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