6-The Rate And Extent Of Chemical Change

Question 1

What is the rate of reaction

Answer 1

How fast the reactants change into products

Question 2

What is an example of a slow rate of reaction

Answer 2

Chemical weathering

Question 3

What is an example of a fast rate of reaction

Answer 3

Explosions are very fast and release a lot of gas

Question 4

What does the rate of a chemical reaction depend on

Answer 4

The collision frequency,

Energy transferred during collision- need enough energy to be successful

Question 5

What 4 things increase rate of reaction

Answer 5

Temperature,
Surface area,
Concentration of solution or pressure of gas,
Presence of a catalyst

Question 6

Why does increasing temperature increase the rate of reaction

Answer 6

Particles gain more energy and move faster, this means they collide more frequently.
Also more energy from temperature means that more collisions will be successful

Question 7

Why does increasing concentration or pressure increase the rate

Answer 7

More particles in the same volume so more frequent collisions

Question 8

Why does increasing surface area increase rate

Answer 8

For the same volume of the solid there is more area for the particles to collide into

Question 9

How does a catalyst work

Answer 9

It decreases the activation energy needed by providing an alternative reaction pathway

Question 10

What is the equation for rate of reaction

Answer 10

Rate of reaction = amount of reactant used or amount of product formed / Time

Question 11

How do u test the rate of reaction with precipitates or colour changes

Answer 11

Place the conical flask on a white tile with a cross on it,
Add reactants and time how long it takes for the cross to no longer be visible.

Or time how long it takes for the solution to change colour

Question 12

How do u measure rate of reaction with the change in mass (usually gas given off)

Answer 12

As gas is released, the mass that disappears is measured on the balance.
The quicker the reading the faster the reaction

Question 13

How do you measure rate of reaction rate with the volume of gas given off

Answer 13

Uses a gas syringe to measure the volume of gas given off.

The more gas given off in a time interval, the faster the reaction

Question 14

What happens when magnesium ribbon is added to dilute hydrochloric acid

Answer 14

Gas is given off so the mass reduces

Question 15

What happens when sodium thiosulfate reacts with HCL

Answer 15

Produces a yellow precipitate which clouds the solution

Question 16

What is equilibrium in reversible reactions

Answer 16

Both the forward and backward reactions happen at the same rate so there is no overall effect

Question 17

When can equilibrium take place

Answer 17

It can only take place in a closed system where none of the reactants or products can escape

Question 18

What does the position of equilibrium depend on

Answer 18

Temperature
Pressure
Concentration

Question 19

What is Le Chatelier’s Principle

Answer 19

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

Question 20

What happens when you decrease the temperature in equilibrium

Answer 20

The equilibrium will move to the exothermic direction to produce more heat

Question 21

What happens when you increase the pressure of equilibrium

Answer 21

The equilibrium tries to reduce the pressure by moving in the direction where there are fewer molecules of gas

Question 22

What happens when you increase the concentration of reactants in equilibrium

Answer 22

It will no longer be in equilibrium so the system tries to bring it back by making more products