Energy and Chemical Reactions

Question 1

What is energy?

Answer 1

The capacity to do work

Question 2

What are 2 types of energy?

Answer 2

• kinetic (energy of motion)
• potential (energy of position)

Question 3

What are the 4 forms of energy?

Answer 3

• mechanical
• radiant
• electrical
• chemical

Question 4

What is mechanical energy?

Answer 4

• energy involved in moving matter
• muscles provide mechanical energy to move objects

Question 5

What is radiant energy?

Answer 5

• kinetic energy of electromagnetic waves (heat and light) also called electromagnetic radiation
• skin uses ultraviolet light to make vitamin D
• the eye is sensitive to visible light

Question 6

What is electrical energy?

Answer 6

• kinetic energy of charged particles travelling through a medium
• responsible for transmission of impulses in nerve and muscle cells

Question 7

What is chemical energy?

Answer 7

• potential energy stored in bonds between atoms and molecules
• energy required to make a bond
• energy released when bonds are broken

Question 8

What is a reactant?

Answer 8

A substance entering the reaction

Question 9

What is a product?

Answer 9

A substance produced by a reaction

Question 10

What is a chemical reaction?

Answer 10

• a chemical reaction rearranges the atoms of reactants to create different products
• is governed by the law of conservation of mass (in a closed system, no atoms are created or destroyed)
  - mass of the products = mass of the reactants

Question 11

What is metabolism?

Answer 11

• the sum of all chemical reactions, within a living organism

Question 12

What are the 2 types of reactions that make up metabolism?

Answer 12

• Anabolic reactions (bond formation; requires input of energy, endergonic)
• Catabolic reactions (bond breaking; releases energy, exergonic)

Question 13

What are the 3 types of reactions?

Answer 13

• Synthesis
• Decomposition
• Exchange

Question 14

What is a synthesis reaction?

Answer 14

• 2 components bond to make larger molecules
• these reactions are anabolic and endergonic (requires input of energy)
• ex. N + 3H ——> NH3

Question 15

What is a decomposition reaction?

Answer 15

• bonds between components of a larger molecule are broken, resulting in smaller products
• these reactions are catabolic and exergonic (breaks down bonds)
• ex. NH3 ——> N + 3H

Question 16

What is an exchange reaction?

Answer 16

• bonds are formed and broken down such that reactants are rearranged
• ex. 4NH3 + 3O2 —–> 2H2 + 6H2O

Question 17

Most reactions in the human body have a predictable direction. True or false?

Answer 17

True

Question 18

In theory, reactions are reversible. True or false?

Answer 18

True

Question 19

What are the properties that influence reaction rate?

Answer 19

Properties of Reactant: Surface area, gases/liquids/solids, how reactive the elements are

Temperature: Thermal energy increases the kinetic energy of subatomic particles

Concentration and Pressure: Makes it more likely for particles to collide

Catalyst: A substance that increases the rate of a chemical reaction without changing itself
- this is an enzyme: a protein that speeds up a reaction by lowering the activation energy

Question 19

What is activation energy?

Answer 19

The minimum energy needed to break down the bonds on reactants

Question 19

What is the function of an enzyme as a catalyst?

Answer 19

It means that less activation energy is required in the presence of an enzyme