lesson 4

Question 1

What is a chemical reaction?

Answer 1

A process that leads to the transformation of one set of chemical substances to another.

Question 2

What are the reactants in a chemical reaction?

Answer 2

The starting materials that undergo change during the reaction.

Question 3

What are products in a chemical reaction?

Answer 3

The substances that are formed as a result of the chemical reaction.

Question 4

True or False: All chemical reactions are reversible.

Answer 4

False.

Question 5

What is the law of conservation of mass?

Answer 5

Mass is neither created nor destroyed in a chemical reaction.

Question 6

Fill in the blank: In a chemical equation, the reactants are shown on the _____ side.

Answer 6

left

Question 7

What is a balanced chemical equation?

Answer 7

An equation that has the same number of atoms of each element on both sides.

Question 8

What does the symbol ‘→’ represent in a chemical equation?

Answer 8

It indicates the direction of the reaction from reactants to products.

Question 9

What is an exothermic reaction?

Answer 9

A reaction that releases energy in the form of heat.

Question 10

What is an endothermic reaction?

Answer 10

A reaction that absorbs energy from its surroundings.

Question 11

True or False: Catalysts are consumed in a chemical reaction.

Answer 11

False.

Question 12

What is a catalyst?

Answer 12

A substance that increases the rate of a chemical reaction without being consumed.

Question 13

What is activation energy?

Answer 13

The minimum energy required for a chemical reaction to occur.

Question 14

What is a synthesis reaction?

Answer 14

A reaction where two or more substances combine to form a single product.

Question 15

What is a decomposition reaction?

Answer 15

A reaction where a single compound breaks down into two or more products.

Question 16

What is a single replacement reaction?

Answer 16

A reaction where one element replaces another in a compound.

Question 17

What is a double replacement reaction?

Answer 17

A reaction where the ions of two compounds exchange places in an aqueous solution.

Question 18

What is oxidation?

Answer 18

The loss of electrons from a substance during a chemical reaction.

Question 19

What is reduction?

Answer 19

The gain of electrons by a substance during a chemical reaction.

Question 20

What is a redox reaction?

Answer 20

A reaction that involves the transfer of electrons between two species.

Question 21

True or False: In a redox reaction, oxidation and reduction occur simultaneously.

Answer 21

True.

Question 22

What is a combustion reaction?

Answer 22

A reaction where a substance combines with oxygen to produce energy, usually in the form of heat and light.

Question 23

What is a precipitation reaction?

Answer 23

A reaction that occurs when two soluble salts react in solution to form an insoluble product.

Question 24

Fill in the blank: The pH scale measures the _____ of a solution.

Answer 24

acidity or alkalinity

Question 25

What is a neutralization reaction?

Answer 25

A reaction between an acid and a base to produce water and a salt.

Question 26

What is the difference between a homogeneous and heterogeneous mixture?

Answer 26

Homogeneous mixtures have a uniform composition, while heterogeneous mixtures do not.

Question 27

What role does temperature play in chemical reactions?

Answer 27

Increasing temperature generally increases the rate of a chemical reaction.

Question 28

What is concentration in the context of chemical reactions?

Answer 28

The amount of a substance in a given volume of solution.

Question 29

How does surface area affect reaction rates?

Answer 29

Increasing surface area increases the rate of reaction by allowing more collisions.

Question 30

What is the effect of pressure on gaseous reactions?

Answer 30

Increasing pressure generally increases the rate of reaction for gaseous reactants.

Question 31

True or False: A reaction can occur without a catalyst.

Answer 31

True.

Question 32

What is the purpose of a reaction mechanism?

Answer 32

To describe the step-by-step sequence of elementary reactions that lead to the overall reaction.

Question 33

What is an equilibrium in a chemical reaction?

Answer 33

A state where the rates of the forward and reverse reactions are equal.

Question 34

What is Le Chatelier's Principle?

Answer 34

If a system at equilibrium is subjected to a change, the system shifts in a direction that counteracts the change.

Question 35

What is a homogeneous equilibrium?

Answer 35

An equilibrium involving reactants and products in the same phase.

Question 36

What is a heterogeneous equilibrium?

Answer 36

An equilibrium involving reactants and products in different phases.

Question 37

Fill in the blank: The rate of a chemical reaction can be affected by _____, _____, and _____ (name three factors).

Answer 37

temperature, concentration, surface area

Question 38

What is a reaction rate?

Answer 38

The speed at which reactants are converted into products in a chemical reaction.

Question 39

What is the difference between a fast and slow reaction?

Answer 39

Fast reactions occur in a short amount of time, while slow reactions take a longer time to complete.

Question 40

What is a homogeneous catalyst?

Answer 40

A catalyst that is in the same phase as the reactants.

Question 41

What is a heterogeneous catalyst?

Answer 41

A catalyst that is in a different phase than the reactants.

Question 42

What are enzyme-catalyzed reactions?

Answer 42

Reactions that are sped up by enzymes, which are biological catalysts.

Question 43

What is the role of enzymes in biological reactions?

Answer 43

Enzymes lower the activation energy required for reactions, increasing their rate.

Question 44

What is an inhibitor?

Answer 44

A substance that decreases the rate of a chemical reaction.

Question 45

What is a transition state?

Answer 45

A high-energy state during a reaction that occurs between reactants and products.

Question 46

True or False: All chemical reactions involve breaking and forming bonds.

Answer 46

True.

Question 47

What is a molecular formula?

Answer 47

A representation of a molecule that shows the number and types of atoms present.

Question 48

What is a structural formula?

Answer 48

A representation that shows how atoms are arranged in a molecule.