GCSE Rates Of Reaction

Question 1

Equation for calculating the average rate of reaction

Answer 1

Rate= Change in amount of product formed
—————————————————
Time

Question 2

What does the gradient tell us?

Answer 2

The rate of reaction is quicker if steeper and slower if shallower

Question 3

Describe collision theory

Answer 3

In order for a reaction to occur particles must collide with energy greater than or equal to the activation energy.

Question 4

What is a catalyst?

Answer 4

A substance that speeds up the rate of reaction but remains chemically unchanged at the end of the experiment.

Question 5

How does temperature affect the rate of reaction?

Answer 5

• at higher temp particles have more kinetic energy and move around faster.
  -this results in more collisions per unit time between reactant particles.
• in addition, more particles will collide with energy greater than or equal to the activation energy.
  -therefore more of the collisions will be successful

Question 6

How does the pressure of gases affect the rate of reaction?

Answer 6

• increasing the pressure means that there are more reactant particles in a given volume.
• as a result, there are more collisions between reactant particles per unit time, therefore more successful collisions so the rate of reaction increases.

Question 7

How does increasing concentration of solutions affect the rate of reaction?

Answer 7

-increasing concentration of a reactant in solution means that there are more particles of that reactant in a given volume.
- as a result, there are more collisions between reactant particles per unit time.
- so the rate of reaction increases

Question 8

How does surface area affect the rate of reaction?

Answer 8

• smaller pieces have a larger surface area than larger pieces with the same total mass.
• this means that more particles of the solid reactant are in contact with particles of the other reactant. This results in more collisions between reactant particles per unit time, so the rate of reaction increases.

Question 9

How does a catalyst increase the rate of reaction?

Answer 9

• provide an alternate reaction pathway with a lower activation energy.
• this means that more collisions will have energy equal to/ greater than the activation energy, so more of the collisions will be successful

Question 10

Which experiment is for The effect of surface area on rate of reaction?

Answer 10

Small Marble chips and large marble chips and hydrochloric acid

Question 11

Word equation of marble chips and hydrochloric

Answer 11

Calcium Carbonate + hydrochloric acid = Calcium Chloride + water + Carbon Dioxide

Question 12

Symbol equation for marble chips hydrochloric acid

Answer 12

CaCO3(s) + 2HCl(aq) = CaCl2(aq) + H20(l) + CO2(g)

Question 13

What is the rate of reaction?

Answer 13

The rate of reaction is a measure of the number of successful collisions per unit time.

Question 14

How does the gradient typically change during a reaction?

Answer 14

It starts of steep then gradually gets less steep until the graph plateaus and the reaction stops

Question 15

Activation energy

Answer 15

The minimum amount of energy, particles must possess for them to react when they collide

Question 16

Marble chips experiment method concentration

Answer 16

1. Set up the apparatus and clamp the gas syringe in place.
2. Measure the hydrochloric acid into the conical flask and add the marble chips to the conical flask.
3. Quickly replace the bung and start a timer. Swirl frequently.
4. Record the time take for 50cm3 of gas to be produced.
5. Repeat the experiment with the same marble chips but different concentrations of acid.

Question 17

Marble chips surface area method

Answer 17

1. Place a measuring cylinder upside down in the water trough. The measuring cylinder should be completely full of water.
2. Clamp the measuring cylinder in place.
3. Measure the hydrochloric acid into the conical flask.
4. Add the large marble child to the conical flask, quickly replace the bung and start the timer.
5. Stir well and record the volume of gas produced every 10 seconds.