Question 1

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

Accepted Answer

CH\_2O

Question 2

A sample of a compound has a molar mass of 180 g/mol and an empirical formula of CH\_2O. What is the molecular formula?

Accepted Answer

C\_6H\_12O\_6

Question 3

Which of the following is NOT evidence of a chemical reaction?

Accepted Answer

Melting of ice

Question 4

A student mixes solutions of silver nitrate and sodium chloride. A white solid forms. Which type of chemical reaction is this?

Accepted Answer

Double displacement (precipitation)

Question 5

Which law states that the total mass of reactants equals the total mass of products in a chemical reaction?

Accepted Answer

Law of Conservation of Mass

Question 6

Balance the following equation: $$\mathrm{C_2H_6 + O_2$ \rightarrow CO_2$ + H_2O}$$

Accepted Answer

$$\mathrm{2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O}$$

Question 7

What is the percent composition of sodium in sodium chloride ($$\mathrm{NaCl}$$)? (Atomic masses: Na = 23.0, Cl = 35.5)

Accepted Answer

39.3%

Question 8

How many moles are in 36 grams of water ($$\mathrm{H_2O}$$)? (Molar mass of $$\mathrm{H_2O} = 18 g/$$mol)

Accepted Answer

2 moles

Question 9

Which of the following bonds is most polar?

Accepted Answer

O-H

Question 10

Which molecule has a dipole moment?

Accepted Answer

$$\mathrm{H_2O}$$

Question 11

Which of the following is a pure covalent bond?

Accepted Answer

Cl-Cl

Question 12

Which element has the highest electronegativity?

Accepted Answer

Fluorine

Question 13

What is the electron geometry of methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

Tetrahedral

Question 14

Which of the following molecules is nonpolar?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 15

Draw the Lewis structure for $$\mathrm{NH_3$}$$ and determine the number of lone pairs on the central atom.

Accepted Answer

1 lone pair

Question 16

A reaction produces 8.0 g of water from 4.0 g of hydrogen and 32.0 g of oxygen. According to the Law of Conservation of Mass, what is the total mass of reactants?

Accepted Answer

36.0 g

Question 17

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by transferring electrons from one atom to another

Question 18

A student needs to prepare 0.5 moles of $$\mathrm{NaCl}. $$How many grams of $$\mathrm{NaCl}$$ should they weigh out? (Molar mass of $$\mathrm{NaCl} = 58.5 g/$$mol)

Accepted Answer

29.25 g

Question 19

Which molecular geometry is observed in $$\mathrm{CO_2$}$$?

Accepted Answer

Linear

Question 20

Which of the following is a chemical change?

Accepted Answer

Burning wood

CHEM 110 Lab Exam 2 Study Notes: Chemical Composition, Reactions, and Bonding

Study Guide - Practice Questions

Study Guide - Flashcards