Rates Of Reaction -How The Change Of Concentration In Sodium Thiosulphate Affects Its Reaction Rate

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Joe Barrick 11BUN April, 2005

Rates Of Reaction -

How The Change Of Concentration In Sodium Thiosulphate Affects Its Reaction Rate

Introduction

In my experiment I will investigate how the rate of reaction of Sodium Thiosulphate will be affected by the change in its concentration. But before this I carried out a trail experiment to see which solution, Sodium Thiosulphate or Hydrochloric acid would be more suitable.

My Trail Experiment Method was to first collect all of the equipment needed, then I measured out the right amounts of each solution by measuring from the bottom of the meniscus. Then I put the solutions into a conical flask and timed how long it took for the paper cross underneath the flask to disappear. I tested both solutions by changing the concentration of one, then of the other but I kept the total volume the same. I repeated the experiment again to make my results more accurate, these were my results:

Volume of Sodium Thiosulphate

(cm3)

Volume of Hydrochloric Acid

(cm3)

Volume of Water

(cm3)

Time Taken

st

(seconds)

Time Taken

2nd

(seconds)

Time Taken

Average

(seconds)

0

0

20

5

20

5

0

0

0

5

0

5

67

66

38

57

74

60

39

61

70.5

63.0

38.5

59.0

My Prediction

I predict that the more concentrated the Sodium Thiosulphate is the quicker the reaction will take place. The less amount of Sodium Thiosulphate and more amount of water the slower the reaction rate will be. I know this because the scientific knowledge says that the more molecules there are in the Sodium Thiosulphate the more chance of a collision with the Hydrochloric Acid there will be. When the molecules collide together a reaction takes place and once all the molecules have collided with each other the reaction has then finished.
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I am choosing to change the concentration of Sodium Thiosulphate as it reacts faster than the Hydrochloric Acid and will give me a better range of results therefore giving me a better graph to plot. The Hydrochloric acids results were to close together as it was slow to react.

Safe And Fair Test

I am going to make this experiment safe by wearing safety goggles at all times when using chemicals and I will conduct a fair procedure by keeping all the equipment the same for both sets of tests and by keeping the total ...

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