3- Reaction rates and states of matter

Question 1

What is energy?

Answer 1

energy is the ability to do work

Question 2

Two classifications of energy?

Answer 2

1- Potential energy; result of position, condition, composition (chemical/nuclear)

2- Kinetic energy; because of motion (mechanical/electrical)

Question 3

What is a reaction rate?

Answer 3

the rate at which reactants are consumed, or products are produced, in a chemical reaction

Question 4

What determines a reaction rate?

Answer 4

The speed at which reactant(s) is/are used up​
The speed at which product(s) is/are formed​

eg Reactions which require the breaking of covalent bonds are slow and have higher activation energies.​ (ionic=faster)

Question 5

What is activation energy?

Answer 5

the amount of energy required to activate a transformation of reactants to products

Question 6

What occurs in an exothermic reaction?

Answer 6

energy is released as the reaction occurs

reactants have more energy than the products

Question 7

What is an endothermic reaction?

Answer 7

energy is required for the reaction to occur (eg photosynthesis)

(Endothermic reactions occur when the energy required to break bonds in the reactants is more than the energy released by the bond formation in the products)

Question 8

What is a catalyst in a living system?

Answer 8

Enzymes

Question 9

Name 4 factors that affect the rate of reaction

Answer 9

1- Physical Nature of Reactants
2- Reactant Concentrations
3- Reaction Temperature
4- Presence of Catalysts

Question 10

How does the physical nature of reactants affect a reaction?

Answer 10

A reaction will occur faster when the reactants are in the same physical state, which includes ​the physical state of each reactant (s, l, or g) and the particle size.

Question 11

How do the reactant concentrations affect a reaction?

Answer 11

Reaction rate increases as concentration increases​ due to an increased rate of collisions

Question 12

How does the reaction temperature affect a reaction?

Answer 12

A higher temperature provides reactant molecules with more kinetic energy and an increased molecular speed

Question 13

How does the presence of catalysts affect a reaction?

Answer 13

The presence of catalysts in a reaction lower the activation energy, which creates a more favourable environment for the reaction to occur​.
(reaction rate increases)

Question 14

What is a catalyst?

Answer 14

a substance that increases a chemical reaction rate without being consumed in the chemical reaction

Question 15

How to catalysts increase reaction rates?

Answer 15

LOWERS THE ACTIVATION ENERGY = increase the reaction rate

Question 16

What are intermolecular forces responsible for?

Answer 16

Keeping molecules together

the strength of these forces that determine if a substance will be a solid, liquid, or gas

Question 17

Name 3 types of intermolecular forces

Answer 17

1- Hydrogen bonds (not true chemical bonds)​
2- Dipole-dipole attractions​
3- Dispersion forces

Question 18

What are intramolecular forces?

Answer 18

Intramolecular forces are the bonds that hold different molecules to one another, and are referred to as the true chemical bonds​.

Question 19

Name 2 types of intramolecular forces

Answer 19

1- Ionic bonds within ionic compounds​

1- Covalent bonds within covalent compounds​

Question 20

What is the strongest type of bond?

Answer 20

Hydrogen bond

Question 21

Where do hydrogen bonds occur?

Answer 21

Hydrogen bonds occur between polar molecules within a hydrogen-containing molecule: a hydrogen atom with low electronegativity is covalently bonded to a highly electronegative element

Question 22

What are dipole-dipole attractions?

Answer 22

Attractive forces in polar molecules

eg hydrogen bond

Question 23

What are dispersion forces?

Answer 23

weak attractions between non-polar molecules​ that result from momentary uneven electron distributions within the molecules​

Question 24

What are ionic bonds?

Answer 24

strong attractive forces that hold positive and negative ions together.

Question 25

Why do ionic bonds have high melting points?

Answer 25

Because they require large amounts of energy to break apart ionic bond

Question 26

What state of matter has the highest kinetic energy?

Answer 26

Gas

Question 27

How to calculate pressure?

Answer 27

Pressure = Force / Area

Question 28

What is Boyle’s Law?

Answer 28

Boyle’s Law​ describes the pressure-volume relationship:​ as volume decreases, increases (and vice versa)
eg breathing (air moves in and out to the lower pressure region)

Question 29

What is Dalton’s Law?

Answer 29

the total pressure exerted by a mixture of gases is the sum of the partial pressures of the individual gases present​.

Question 30

What is solubility?

Answer 30

Solubility is a measure of how much of a substance will dissolve in a solvent
(like dissolves like)

Question 31

What is a saturated solution?

Answer 31

A saturated solution​ contains the maximum amount of solute that can be dissolved in the solution

Question 32

Name 3 factors that affect solubility

Answer 32

1- Size of solute particles​: Smaller particles dissolves faster​

2- The degree of mixing​: Vigorous mixing allows more solutes to dissolve

3- Temperature​: Solubility increases with an increase in temperature​

Question 33

What is Henry’s Law?

Answer 33

Henry’s Law states that the solubility of a gas is directly proportional to pressure​:

As pressure increases the gas because more soluble, dissolving more readily​
As pressure decreases the gas because less soluble, dissolving less readily​

Question 34

How does a chemical reaction occur?

Answer 34

through collisions between molecules; the faster they collide, the faster the reaction occurs