4.3.2 - effect of concentration/pressure Flashcards
1
Q
increasing concentration / pressure increases rate because …
A
- there are more particles per unit volume
- so the collision frequency is higher
- so there are more successful collisions per unit time
2
Q
how can increasing concentration be accomplished?
A
dissolving more solute particles
3
Q
how can increasing pressure be accomplished?
A
making the reaction vessel smaller
4
Q
how can the effect of concentration on rate be demonstrated?
A
by reacting sodium thiosulphate solution with hydrochloric acid (disappearing cross experiment)
5
Q
disappearing cross experiment:
A
- 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
6
Q
how is rate calculated?
A
rate (s^-1) = 1/time taken
7
Q
results of disappearing cross experiment:
A
- rate is proportional to concentration
