Chapter 2: Molecules and Solutions EST

Question 1

What is a polyatomic ion?

Answer 1

A group of atoms that carry a charge and act as a single ion.

Question 2

What kind of bond forms between a metal and a non-metal?

Answer 2

Ionic bond → electrons are transferred.

Question 3

What kind of bond forms between two non-metals?

Answer 3

Covalent bond → electrons are shared.

Question 4

What is the crossover rule?

Answer 4

A trick to determine ionic compound formulas by swapping ion charges.

Question 5

What is the formula for aluminum bromide?

Answer 5

Al³⁺ + Br⁻ → AlBr₃

Question 6

What is the formula for calcium nitride?

Answer 6

Ca²⁺ + N³⁻ → Ca₃N₂

Question 7

What is the name of MgF₂?

Answer 7

Magnesium fluoride (ionic = no prefixes)

Question 8

What is the name of CO₂?

Answer 8

Carbon dioxide (covalent = uses prefixes)

Question 9

What is molar concentration (mol/L)?

Answer 9

The amount of solute (in moles) per liter of solution.

Question 10

Convert 9 mol of H₂ in 17 L to mol/L.

Answer 10

9 ÷ 17 = 0.53 mol/L

Question 11

Convert 125 g of Na in 5 L to mol/L (Na = 23 g/mol).

Answer 11

125 ÷ 23 = 5.43 mol → 5.43 ÷ 5 = 1.09 mol/L

Question 12

What is the difference between a strong and weak electrolyte?

Answer 12

Strong = 100% ionization; Weak = less than 10% ionization

Question 13

What does pH measure?

Answer 13

The concentration of H⁺ ions in a solution.

Question 14

Formula: [H⁺] = ?

Answer 14

10^(-pH)

Question 15

How many times more acidic is pH 2 than pH 5?

Answer 15

10^(5-2) = 10³ = 1000 times more acidic

Question 16

What is [H⁺] at pH 3?

Answer 16

[H⁺] = 10^(-3) = 0.001 mol/L