Chapter 1- Catalysts

Question 1

3 things that must happen in a collision

Answer 1

The reactant particles must collide
The particles must have sufficient energy to break the reactant bonds
The orientation of particles that collide must be favourable to form products.

Question 2

What must happen for a reaction to occur?

Answer 2

For a reaction to occur, particles must collide with energy equal to or greater than the activation energy.

Question 3

Why do reactions occur faster in solution?

Answer 3

Reactions occur faster in solutions because no bond breaking is required.

Question 4

How does having the reactant as a powder increase the reaction rate?

Answer 4

Having the reactant as a powder gives the reaction a greater reaction rate because powders have greater surface area and having a greater surface area creates more opportunities for collisions.

Question 5

What does increasing the concentration of a reactant do?

Answer 5

Increasing the concentration of a reactant will increase the reaction rate because at higher concentrations there will be a greater proportion of successful collisions per unit time.

Question 6

What is the relationship between collision energy and activation energy?

Answer 6

Collision energy is equal to or greater than the activation energy.

Question 7

Define catalyst.

Answer 7

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

Question 8

How do catalysts increase the reaction rate of a chemical reaction?

Answer 8

Catalysts increase the reaction rate of a chemical reaction by providing a reaction pathway; a series of changes by which reactants change to products with a lower activation energy.

Question 9

What is enthalpy?

Answer 9

Enthalpy, or chemical potential energy is is energy stored in in chemical bonds.

Question 10

What are factors that effect the rate of chemical reactions?

Answer 10

Factors that effect rate of chemical reaction are the nature of the reactants, the concentration of reactants, the state of subdivision of the reactants, temperature and catalysts.

Question 11

How does a catalyst act as a catalyst?

Answer 11

A catalyst acts as a catalyst by providing an alternative shorter activation energy pathway and reforms after the reaction.

Question 12

What is the purpose of a catalyst?

Answer 12

The purpose of a catalyst is to increase the rate of chemical reaction and form products faster using less activation energy.

Question 13

What is the rate of reaction formula?

Answer 13

The rate of reaction is equal to amount of reactant used or product formed divided by time and the unit is per second.

Question 14

What does increasing the temperature do to a reaction?

Answer 14

Increasing the temperature of a chemical reaction increases the number of collisions which increases reaction rate.

Question 15

What effect does the bond strength have on enthalpy?

Answer 15

A weak bond means a high enthalpy and a strong bond means a low enthalpy.

Question 16

What is the change in enthalpy equal to?

Answer 16

The change in enthalpy is equal to the enthalpy of the products less the enthalpy of the reactants.

Question 17

What is the transition state for a reaction?

Answer 17

The transition state or activated complex for a reaction is:
The highest potential energy state that is reached in the system.
formed during the bond breaking and bond formation process.
unstable and is never present as a product of the reaction.

Question 18

What is the difference in potential energy between the reactant particles and the transition state?

Answer 18

The difference in potential energy between the reactant particles and the transition state is is called the activation energy for the reaction.

Question 19

What is the change in enthalpy?

Answer 19

The change in enthalpy also known as the heat of reaction shown as delta H is the difference between the energy of the reactant particles and the potential energy of the product particles.

Question 20

What do enzymes do?

Answer 20

Enzymes catalyse chemical reactions in living things.

Question 21

What are enzymes?

Answer 21

Enzymes are very large proteins which have specifically shaped sections that are described as active sites.

Question 22

What can active sites interact with?

Answer 22

Active sites can only interact with particular reactants.

Question 23

What is a substrate?

Answer 23

A substrate is the reactant that is broken down by an enzyme into two smaller molecules.

Question 24

What is the order of the enzyme and substrate reaction?

Answer 24

The order of the enzyme and substrate reaction is:
The substrate enters the enzymes active site.
Interactions occur the enzyme and substrate, forming an enzyme-substrate complex and bonds break in the substrate.
The enzyme molecule is regenerated and products are released.

Question 25

What are the differences between inorganic catalysts and enzymes?

Answer 25

The differences between inorganic substances and enzymes are is that enzymes:
Can produce much faster reaction rates
Are considerably more selective, usually catalysing only one specific biochemical reaction.
Are much more sensitive to pH changes and temperature changes because the intricate three dimensional structure of their active site is destroyed at high temperatures as pH changes.