Topic 15 - Moles 2

Question 1

how do you calculate gas volume

Answer 1

volume = mass x 24

VOLUME IS dm3

Question 2

How do you change cm3 into dm3

Answer 2

Divide by 1000

Question 3

How do you calculate concentration?

Answer 3

moles
Concentration = ————
(mol/dm3) volume

Question 4

What is the point of titration practicals?

Answer 4

To measure moles in solutions

Acid + alkali react in a fixed mole ratio

Question 5

Describe the method for a titration practical

Answer 5

1) use a pipette and a puppeteer filler to place 25cm3 of alkali into a flask with 2-3 drops of indicator (NOT universal!)
2) fill a burette with acid (of a known concentration ) and note the initial volume - do this below eye level
3) add acid from the burette, swirling until the colour in the flask changes
4) note the final burette volume
5) the titre is the volume added form the burette
6) repeat until you have 3 sets of concordant results