Unit 6: Chemical Reactions

Question 1

What are reactants?

Answer 1

The substances that undergo change in a chemical reaction.

Question 2

What are products?

Answer 2

Substances formed as a result of change.

Question 3

What is a chemical equation?

Answer 3

A representation of a chemical reaction in which the reactants and the products are expressed as chemical formulas.

Question 4

What does the Law of Conservation of mass state?

Answer 4

The mass of a closed system of substances will remain constant. Matter cannot be created or destroyed.

Question 5

Who established the Law of Conservation of Mass?

Answer 5

Antoine Lavoisier in 1789.

Question 6

What is a mole?

Answer 6

An amount of substance that contains Avogadro’s number of particles of that substance.

Question 7

What is Avogadro’s number?

Answer 7

6.02x10^23

Question 8

What is molar mass?

Answer 8

The mass of one mole of a substance.

Question 9

What is a synthesis reaction?

Answer 9

Two or more reactants combine to form one product.

A+B->AB

Question 10

What is a decomposition reaction?

Answer 10

One reactant breaks down into two or more simpler substances.

AB -> A + B

Question 11

What is a single displacement reaction?

Answer 11

One single element replaces an element in a compound.

AB + X -> XB + A

Question 12

What is a double displacement reaction?

Answer 12

The ions in two ionic compounds switch places to form two new ionic compounds.

AB + XY -> AY + XB

Question 13

What is combustion?

Answer 13

Something is burning; reacting rapidly with oxygen. Heat and light are produced, each reaction has oxygen as a reactant and carbon dioxide and water as two products.

Question 14

What is a redox reaction?

Answer 14

In an oxidation-reduction reaction, electrons are transferred from one reactant to another.

Question 15

What is oxidation?

Answer 15

An element losing its electrons during a chemical reaction.

Question 16

What is reduction?

Answer 16

An element gaining electrons during a chemical reaction.

Question 17

What is chemical energy?

Answer 17

The energy stored in the chemical bonds of a substance. Breaking bonds requires energy, and forming bonds releases energy.

Question 18

What is an exothermic reaction?

Answer 18

A chemical reaction that releases energy to its surroundings.

Reactants -> products + energy

Energy released > energy required

Question 19

What are examples of exothermic reactions?

Answer 19

Combustion

Respiration

Question 20

What is an endothermic reaction?

Answer 20

A chemical reaction that absorbs energy from its surroundings.

Reactants + Energy = Products
Energy required > energy released

Question 21

What is an example of an endothermic reaction?

Answer 21

Photosynthesis.

Question 22

What is reaction rate?

Answer 22

The rate at which reactants change into products over time. Measured by how quickly the reactants decrease or how quickly the products increase.

Question 23

What factors affect reaction rate?

Answer 23

Temperature 
Surface area
Concentration
Stirring
Pressure
Catalysts

Question 24

What is a catalyst?

Answer 24

A substance that affects the reaction rate without being used up in the reaction.

Question 25

What is equilibrium?

Answer 25

The state in which the forward and reverse paths of a change take place at the same rate so that the concentration of the reactants and products doesn’t change with time.

Question 26

What are physical and chemical equilibrium?

Answer 26

Physical is opposing physical changes happening at the same rate, while chemical is opposing chemical changes happening at the same rate.

Question 27

What are forward and reverse reactions?

Answer 27

Forward reaction is reactants changing into products and reverse reaction is products changing back into reactants.

Question 28

What is Le Chatelier’s principle?

Answer 28

If a stress is placed on a system at equilibrium, the system will proceed in a direction that minimizes the stress.