The rate and extent of chemical change

Question 1

What are some examples of slow reactions?

Answer 1

• rusting of iron
• chemical weathering

Question 2

What is an example of moderately sped reactions?

Answer 2

magnesium reacting with acid to produce a gentle stream of bubbles

Question 3

What are some examples of fast reactions?

Answer 3

• burning
• explosions

Question 4

What is activation energy?

Answer 4

the minimum amount of energy the particles need to react

Question 4

What is the collision theory?

Answer 4

• collision frequency of reacting particles- more collisions the faster the reaction
• energy transferred during collision- particles have to collide with enough energy for the collision to be successful

Question 5

What 4 factors does rate of reaction depend on?

Answer 5

• temperature
• concentration of solution or pressure of gas
• surface area
• presence of catalyst

Question 6

Why does increasing the surface area increase the rate of reaction?

Answer 6

• If one of the reactants is a solid, then breaking it up into smaller pieces will increase it’s surface area to volume ratio
• for the small volume of the solid, the particles around it will have more area to work on- so there will be collisions more frequently.

Question 7

What is meant when a system is at equilibrium?

Answer 7

The forward reaction will be going at the exact same rate as the backwards one

Question 8

What does it mean if the equilibrium of a reaction lies to the right?

Answer 8

the concentration of products is greater than that of the reactants

Question 9

What does it mean if the equilibrium of a reaction lies to the left?

Answer 9

the concentration of reactants is greater than that of the products

Question 10

What is Le Chatelier’s Principle?

Answer 10

the idea that if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract the change

Question 11

How does temperature effect reversible reactions?

Answer 11

-if you decrease the temperature, the reaction will move in the exothermic direction to produce more heat. This means you will get more products for the exothermic reaction and less for the endothermic reaction. Vice versa if the temperature increases.

Question 12

How does pressure effect reversible reactions?

Answer 12

• only involves gases
• if you increase the pressure, the equilibrium tries to reduce it- it moves in the direction where there are fewer molecules of gas
• vice versa with decreasing pressure

Question 13

How does concentration effect reversible reactions?

Answer 13

• If you change the concentration of either the reactant or the products, the system will no longer be at equilibrium
• the system needs to bring itself back to equilibrium SO if you increase the concentration of reactants the system tried to decrease it by making more products vice versa