Question

http://papers.xtremepapers.com/CIE/Cambridge%20IGCSE/Chemistry%20(0620)/0620_s11_qp_32.pdf
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Answer 1

@aaronq

Answer 2

so you're asking about the time of experiment 4, right?

Answer 3

yes the time of experiment 4

Answer 4

okay, because everything else is constant, we can ignore their effects on the rate of the reaction.

notice that when you halved the concentration of thiosulfate, you doubled the time

Answer 5

Volume of thiosulphates are halved which are of the same concentration.

Answer 6

so how are the concentration halved

Answer 7

We're just looking for a pattern, look at the first row

volume of thiosulfate/cm3 50 40 25 10

and look at the time it took

time / s 48 60 96 ..........

from 50 mL to 25 mL, the time increased by 2, (96/2=48)

gimme a min to think about this cuz im eating dinner lol

Answer 8

take your time and enjoy :)

Answer 9

i think i have figured it out, if the time in experiment 3 is 2* the experiment 1 then concentration must be halved as concentration and time have an inverse proportion relation ship.

Answer 10

You're right, if you plot the inverse of concentration to the time you get a linear relationship.

So you can take two points and find the equation for a line that represents the time it will take