C6- Rate and extent of chemical reactions

Question 1

Equation to work out any rate

Answer 1

any rate = change in quantity/time

Question 2

Rate of Reaction Practical

Answer 2

Apparatus; conical flask placed over a cross. (Gas syringe)
1. React hydrochloric acid and sodium thiosulfate.
2. Wait until solution goes cloudy (higher turbidity)
3. Measure time for cross to disappear
4. Repeat at different temps.
5. Measure volume of gas produced by attaching a gas syringe to conical flask vessel.

Question 3

What does a gradient on a graph show?

Answer 3

Rate of reaction (g/s or cm^3/s)
any gradient = up/across.

Question 4

What factors can increase rate of reaction?

Answer 4

Surface area
Temperature
Pressure
Concentration
(Particles collide more frequently and with more energy; more likely to be successful)

Question 5

What does a catalyst do?

Answer 5

A catalyst reduces activation energy and so there can be more successful collisions as the minimum energy needed is decreased.

Question 6

What is Le Chatelier’s principle?

Answer 6

• If a system at equilibrium is subjected to a change, the system will adjust to counteract the change.

Question 7

What happens during reversible reactions?

Answer 7

Both the forward and reverse reaction will continue to take place until the rate of both is equal - equilibrium is reached.

Question 8

What can change the quantity of a reversible reaction?

Answer 8

-Increase in pressure/concentration will favour the side that produces fewer moles.
-Increase in temp favours the endothermic reaction.
-Removing product from one side shifts the position of equilibrium to that direction.