Aqa Handbook

Question 1

When assessing uncertainty, there are a number of issues that have to be considered. These include:

Answer 1

 the manufacturer’s tolerance on instruments
 the judgments that are made by the experimenter
 the procedures adopted (eg repeated readings)
 the size of increments available (eg the size of drops from a pipette).

Question 2

Reading

Answer 2

the values found from a single judgement when using a piece of equipment
Eg ph meter
Thermometer
Top pan balance
Measuring cyclinder
Volumetric flask

Question 3

Measurinement

Answer 3

the values taken as the difference between the judgements of two values.

Eg ruler
Stopwatch analogue meter

Question 4

How to decrease uncertainty

Answer 4

Repeated measurements

Choosing appropriate equipment

Question 5

Why is it good to take mmultiple readings

Answer 5

You can easy with identifyi exceptional answers

Question 6

Experimental error in a titration

Answer 6

. For example, the wrong volume of solution added from the burette, the wrong amount of solution measuring the pipette or the end point might have been misjudged.

Question 7

Formula for percentage uncertainty

Answer 7

percentage uncertainty = |best gradient−worst gradient dividented by best gradient then X| 100%

Question 8

What should be considered when drawing the line of best fit?

Answer 8

Are the data likely to be following an underlying equation (for example, a relationship governed by a physical law)? This will help decide if the line should be straight or curved.
 Are there any anomalous results?