Experimental Know-How

Question 1

how do you improve the validity of an experiment

Answer 1

by controlling the variables:
- you can change on variable and measure how it affects another variable
- to make it a fair test, everything else that could affect the results should stay the same

Question 2

what is the variable you change?

Answer 2

independent variable

Question 3

what is the variable you measure?

Answer 3

dependent variable

Question 4

what are control variables?

Answer 4

variables you keep the same

Question 5

why are control experiments carried out?

Answer 5

it is an experiment that is kept under the same conditions as the rest of the investigation, but doesn’t have anything done to it - this is so you can see what happens when nothing is being changed

Question 6

how do improve the reliability of an experiment

Answer 6

• to improve reliability you need to repeat any measurements you make and calculate an average
• you need to repeat each experiment at least three times

Question 7

what are potential hazards in an experiment to consider?

Answer 7

• chemicals
• fire
• electricity

Question 8

how do you reduce risks when working with sulfuric acid?

Answer 8

always wear gloves and safety goggles to reduce the risk of the acid coming into contact with your skin and eyes

Question 9

how do you reduce risks when using a Bunsen burner?

Answer 9

stand it on a heat proof mat to reduce the risk of starting a fire

Question 10

how do you reduce risks when working with chemicals that give off harmful gases?

Answer 10

you use a fume cupboard to reduce the risk of breathing in the gases

Question 11

how do you make sure results are as accurate as possible?

Answer 11

you need to make sure you are measuring the right thing and don’t miss anything or include anything that shouldn’t be included in the measurements

Question 12

how do you make results precise?

Answer 12

precise results are ones where the data is all really class to the mean - do not include anomalies