Required Practicle: Rates Of Reaction

Question 1

What is a hypothesis ?

Answer 1

A proposal that could explain a fact or an observation
This must be testable

Question 2

Why when reacting sodium thiosulfate with hydrochloride acid does it appear cloudy ?

Answer 2

Sulfur solid which makes it appear cloudy

Question 3

What is the method for disappearing cross ?

Answer 3

1. 10cm3 of sodium thiosulfate into conical flask
2. Place flaks over black cross
3. Add 10cm3 of hydrochloric acid into flaks
4. Swirl and start stopwatch
5. Look down and measure time taken for cross to no longer be visible
6. Record result and repeat using low concentration of thiosukfate solution
7. Repeat total experiment 3 times and calculate mean values

Question 4

Why is this measument not reproducible ?

Answer 4

It has to be repeatable by another person using a different technique or equipment
Different people have different eyesights
So some can see it for longer than others
However the same size cross some what mitagates this

Question 5

How can we measure the rate of reaction between magnesium and hydrochloride acid ?

Answer 5

Measure volume of hydrogen gas produced

Question 6

What is the method for collecting the volume of gas produced ?

Answer 6

1. 50cm3 of hydrochloride acid into conical flask
2. Add a bung and delivery tube
3. Place delivery tube into container filled with water
4. Place and upside down measuring cylinder over measuring tube
5. add 3cm strip of magnesium to HCL
6. Measure amount of gas trapped in measuring cylinder every 10 seconds until no more is given off
   Repeat using different concentration of HCL

Question 7

What do both these reactions show ?

Answer 7

The greater the concentration the faster the rate of reaction
Meaning they are reproducible