c6: energy changes

Question 1

Rate of reaction equation

Answer 1

change in quantity
—————————
time

Question 2

Rate of reaction practical
(disappearing cross)

Answer 2

hydrochloride acid + sodium thiosulphate in a conical flask sitting over a piece of paper with a cross on
measure time taken for solution to react and go cloudy, to the point where the cross can no longer be seen

repeat at diff temps
hotter temp = takes less time

Question 3

Rate of reaction practical (gas)

Answer 3

measure volume of gas produced by attaching gas syringe to reaction vessel

Question 4

increasing rate of reaction

Answer 4

• increase surface area for solids
• increase concentration for solutions
• increase pressure for gasses

particles collide more frequently due to more kinetic energy

• increase temp: particles move faster, collide more frequently and with more energy: more likely to be more successful collisions
• catalyst reduced activation energy: collisions more likely to be successful

Question 5

Le Chateliers principle:

Answer 5

if a system at equilibrium is subjected to a change, the system will adjust to counteract that change