3.3 Moles and solutions

Question 1

Concentration =

Answer 1

moles
_______
volume

Question 2

How to work out gdm^-3 from moldm^-3

Answer 2

Use moles = mass ÷ Mr and just ignore the dm3

Question 3

What does the accuracy of a measurement depend on?

Answer 3

The accuracy of measurements depends on the quality of the apparatus used, such as a balance, thermometer or glassware

Question 4

What is an uncertainty?

Answer 4

Half a scale division + or - either side of the value measured

Question 5

Equation for % uncertainty

Answer 5

= uncertainty x 100
_____________________
Quantity measured

Question 6

What changes if there are multiple measurements?

Answer 6

There is an uncertainty for each one
You must add the uncertainties together to give you an overall uncertainty of the total answer

Question 7

How do you reduce % uncertainty?

Answer 7

Without changing the measuring instrument: you can increase the amount of substance measured

Question 8

How to calculate uncertainty from % uncertainty?

Answer 8

% uncertainty x reading
_________________________
100