chemistry 5.7 - uncertainty and errors

What is uncertainty?

The maximum error you can have

What is uncertainty caused by?

Limits to the sensitivity of the equipment used

How do you work out the uncertainty of one step of the method in the equipment?

±1/2 of the smallest increment

What causes the uncertainty the manufacturer of equipments write on the packaging?

How accurately the equipment is made

What is the equation for percentage uncertainty?

(Uncertainty / reading) x 100

What can be done to reduce errors?

Using precise equipment and planning experiments with greater volumes

What are systematic errors?

They are caused by the set up, equipment used, etc and will be the same every time the experiment is repeated

What are random errors?

Caused by reading errors, etc and will make all the results a bit different

What does repeating experiments do in terms of errors?

Decrease the effect of random errors but have not effect on systematic errors

How do you work out the overall uncertainty of an experiment?

You find the percentage uncertainty for all the pieces of equipment used and add these up. You then find this percentage of the value that the experiment found