The rate and extent of chemical change

Question 1

How can you find the speed of a reaction?

Answer 1

Recording the amount of PRODUCT FORMED or amount of REACTANT USED UP over TIME.

Question 2

What 4 things affect the rate of reaction.

Answer 2

• Temperature
• The concentration of a solution or pressure of a gas.
• Surface area
• Catalyst

Question 3

How does a change in temperature affect the rate of reaction?

Answer 3

When temp increases particles move faster and have more energy resulting in more SUCCESSFUL COLLISIONS.

Question 4

How does a change in concentration affect the rate of reaction?

Answer 4

If a solution is made more concentrated there are more particles in the SAME VOLUME of solution, so there is a higher collision frequency.

Question 5

How does a change in surface area affect the rate of reaction?

Answer 5

Increasing the surface area of a solid reactant EXPOSES MORE OF ITS PARTICLES, so there is a higher collision frequency.

Question 6

How does the use of a catalyst affect the rate of reaction?

Answer 6

A catalyst speeds up a reaction without being used up. Catalysts DECREASE THE ACTIVATION ENERGY needed for the reaction to occur.

Question 7

What equation do we use to calculate the rate of reaction?

Answer 7

Amount of reactant used up or amount of product formed / time

Question 8

What method would you use to work out the rate of reaction with sodium thiosulfate and HCL.

Answer 8

……………….3
- Put 10cm of SODIUM THIOSULFATE solution into a conical flask.
- Then place the conical flask onto a black CROSS.
…………………………3
- Next add 10cm of HCL into the conical flask.
- SWIRL the solution and start a STOPWATCH.
- Stop the clock when we can NO LONGER SEE the cross.
- Then carry out the experiment again using LOWER CONCENTRATIONS of sodium thiosulfate solution.

Question 9

What product makes the solution go cloudy (aka turbidity)?

Answer 9

Sulfur

Question 10

What problem is there with the disappearing cross experiment?

Answer 10

People have DIFFERENT EYESIGHT’S. Meaning some people can see the cross longer than others so they MAY NOT GET THE SAME RESULTS.

Question 11

What is meant by equilibrium?

Answer 11

Where the forward and reverse reactions will take place at EXACTLY THE SAME RATE.

Question 12

What is meant by Le Chatelier’s Principle?

Answer 12

If a system is at equilibrium and a CHANGE is made to the CONDITIONS, then the system responds to COUNTERACT the change.

Question 13

What happens when we raise the temperature in this reversible reaction?
………….Exothermic……………….
2NO………….⇌…………N..O……..
……..2.Endothermic….2…4……

Answer 13

• The position of equilibrium will SHIFT TO THE LEFT, to reduce the temperature (endothermic).
• Amount of NO would INCREASE and amount of N..O…would DECREASE.
  ………………………..2……………………………………………………….2….4