4.1.3 - Effect Of Concentration / Pressure

Question 1

For Solutions/ Gases, why might INCREASING the Concentration/ Pressure INCREASE RATE !?

Answer 1

. There are more particles per unit volume

. So collision frequency is higher

. So there are more successful collisions per unit time

Question 2

How may you INCREASE the CONCENTRATION of a solution !?

Answer 2

. Increasing the concentration can be accomplished by dissolving more solute particles

Question 3

How might you INCREASE the PRESSURE of a reaction!?

Answer 3

. Increasing the pressure can be accomplished by making the reaction vessel smaller

Question 4

What Experiment can be used to demonstrate the effect of CONCENTRATION on RATE !?

Answer 4

. Disappearing Cross Experiment:
- reacting sodium thiosulphate solution with hydrochloride acid

Question 5

Observations of the DISAPPEARING CROSS Experiment:

Answer 5

. In this reaction, a solid (sulphur) Is slowly produced. After a while, you can’t see through the mixture any longer. This is measured by observing a black cross under the mixture

Question 6

INPUT Variable in the DISAPPEARING CROSS Experiment:

Answer 6

. Concentration of sodium thiosulphate

Question 7

OUTPUT Variable for the DISAPPEARING CROSS Experiment:

Answer 7

. The taken for the cross to disappear

Question 8

CONTROL Variables for the DISAPPEARING CROSS Experiment:

Answer 8

. Total volume of solution

. Concentration of Hydrochloric Acid (aq)

. Temperature

Question 9

Is rate proportional to concentration!?

Answer 9

. Yes