Chemical Reactions

Question 1

What is a precipitation reaction?

Answer 1

A precipitation reaction is one in which dissolved substances react to form one or more solid products.

Question 2

What is solubility?

Answer 2

Solubility is defined as the maximum concentration of a substance that can be achieved under specified conditions.

Question 3

What does it mean when a substance precipitates?

Answer 3

A substance precipitates when solution conditions are such that its concentration exceeds its solubility.

Question 4

What ions do soluble compounds contain?

Answer 4

• Group 1 metal cations (Li⁺, Na⁺, K⁺, Rb⁺, and Cs⁺)
• ammonium ion (NH₄⁺)
• the halide ions (Cl^-, Br^-, and I^-), except halides of Ag⁺, Hg₂²⁺, and Pb²⁺
• the acetate ion (CH₃COO^-)
• the bicarbonate ion (HCO₃^-)
• the nitrate ion (NO₃^-)
• the chlorate ion (ClO₃^-)
• the sulfate ion (SO₄^2-), except sulfates of Ag⁺, Ba²⁺, Ca²⁺, Hg₂²⁺, Pb²⁺, and Sr²⁺

Question 5

What ions do insoluble compounds contain?

Answer 5

• the carbonate ion (CO₃^2-), the chromate ion (CrO₄^2-), the phosphate ion (PO₄^3-), and the sulfide ion (S^2-), except in compounds with Group 1 metal cations and ammonium ion
• the hydroxide ion (OH^-), except hydroxides of Group 1 metal cations and Ba²⁺

Question 6

What is an acid-base reaction?

Answer 6

An acid-base reaction is one in which a hydrogen ion, H⁺, is transferred from one chemical species to another.

Question 7

What is an acid?

Answer 7

An acid is a substance that will dissolve in water to yield hydronium ions (H₃O⁺).

Question 8

What is a strong acid?

Answer 8

A strong acid is one that completely undergoes a reaction when dissolved in water.

Question 9

What is a weak acid?

Answer 9

A weak acid is one that only partially reacts with water, leaving a large majority of dissolved molecules in their orignial form and generation a relatively small amount of hydronium ions.

Question 10

What are some common strong acids?

Answer 10

• hydrobromic acid (HBr)
• hydrochloric acid (HCl)
• hydroiodic acid (HI)
• nitric acid (HNO₃)
• perchloric acid (HClO₄)
• sulfuric acid (H₂SO₄)
• chloric acid (HClO₃)

Question 11

What is a base?

Answer 11

A base is a substance that will dissolve in water to yield hydroxide ions (OH^-).

Question 12

What are strong bases?

Answer 12

Strong bases are those that completely dissociate in water.

Question 13

What are weak bases?

Answer 13

Weak bases are those that produce hydroxide ions when dissolved by chemically reacting with water, and, thus, react only partially.

Question 14

What are some common strong bases?

Answer 14

• lithium hydroxide (LiOH)
• sodium hydroxide (NaOH)
• potassium hydroxide (KOH)
• rubidium hydroxide (RbOH)
• cesium hydroxide (CsOH)
• calcium hydroxide (Ca(OH)₂)
• barium hydroxide (Ba(OH)₂)
• strontium hydroxide (Sr(OH)₂)

Question 15

What is a neutralization reaction?

Answer 15

A neutralization reaction is a specific type of acid-base reaction in which the reactants are an acid and a base, and the products are often a salt and water, and neither reactant is the water itself.

Question 16

What is oxidation?

Answer 16

Oxidation is the loss of electrons, or the increase in oxidation number.

Question 17

What is reduction?

Answer 17

Reduction is the gain of electrons, or the decrease in oxidation number.

Question 18

What is an oxidation-reduction (redox) reaction?

Answer 18

A redox reaction is one in which one or more elements involved undergo a change in oxidation number.

Question 19

What is the oxidation number (or oxidation state)?

Answer 19

The oxidation number (or oxidation state) of an element in a compound is the charge its atoms would possess if the compound was ionic.

Question 20

What are the oxidation numbers for hydrogen?

Answer 20

Hydrogen has a +1 oxidation number when combined with nonmetals, and a -1 oxidation number when combined with metals.

Question 21

What are the oxidation numbers for oxygen?

Answer 21

Oxygen has a -2 oxidation number in most compounds, and a -1 oxidation number in peroxides (O₂^2-).

Question 22

What are the oxidation numbers for fluorine?

Answer 22

Fluorine always has an oxidation number of -1.

Question 23

What are combustion reactions?

Answer 23

Combustion reactions are a type of redox reaction in which the reductant (also called a fuel) and oxidant (often, but not necessarily molecular oxygen) react vigorously and produce significant amounts of heat, and often light, in the form of a flame.

Question 24

What are single-displacement (replacement) reactions?

Answer 24

Single-displacement (replacement) reactions are a type of a redox reaction in which an ion is displaced (or replaced) via the oxidation of a metallic element.

Question 25

What is a limiting reactant?

Answer 25

A limiting reactant is a reactant present in an amount lower than required by the reaction stoichiometry, thus limiting the amount of product generated.

Question 26

What is the formula for percent yield?

Answer 26

percent yield = (actual yield / theoretical yield) x 100