Possible Input Variables
* Surface area
Possible outcome variables
* Colour Change
* Any gases given off
My input variable will be: –
My outcome variable will be: –
My Control Variables will be: –
* Volume of acid
* Volume of thio
* Shape of reacting vessel
The more concentrated the Thio-sulphate solution the least time it takes to react.
Strong Acid Weak acid
If there are more molecules per CM3 they are more likely to collide so there would be a faster rate of reaction.
1. Draw ‘x’ on a piece of paper.
2. Use a measuring cylinder to measure out 50cm3 of thio sulphate and a separate one. to measure out 5cm3 of acid. Always make sure that the glass wear is clean.
3. Place the beaker with 50cm3 of thio sulphate on top of the paper.
4. Add 5cm3 of acid into the solution.
5. Put your head over the beaker so you can see clearly when the ‘x’ disappears.
6. Time how long it takes for the ‘x’ to disappears.
7. Range – 50 thio/ 0 acid – 45 water/ 5 acid
Thio Sulphate solution (cm3)
Time taken (secs) Average
58 53 55.5
61 69 65
77 79 78
87 89 88
94 94 94
106 105 105
110 134 122
130 179 154.5
322 322 322
691 691 691
8. If any results look irregular, repeat or share results with friends.
My graph is a smooth curve. I am confident with my results because my line is on nearly all of the points. My graph shows that the stronger the thio solution the quicker the cross disappears. I know this because when there is 45cm3 of thio solution and only 5 cm3 of water it only takes 65 seconds for the cross to disappear whereas when there is 5cm3 of thio solution and 45cm3 of water it take 691 seconds for the cross to disappear.
I am confident with my results as I made the experiment a fair test by making sure that the glass wear was washed clean after every experiment. Another reason I am confident is because I done the experiment twice and made an average. If I could do the experiment again then I would maybe repeat it one more time to make my results more dependant.