Determination of the Relative Atomic Mass of Lithium

A-Level: Chemistry

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Method

1. Set up the apparatus accordingly (as shown below). Use a standing
clamp to hold the measuring cylinder upright.

2. Ensure the 100 cm measuring cylinder contains exactly 100 cm of
distilled water.

3. Cut a piece of Lithium using a knife and mat.

4. Weigh the cutting of lithium ensuring it is clean and weighs
approximately between 0.08g and 0.13g. Record the mass of lithium
accurately and exact to 3 decimal places.

5. Remove the stopper from the conical flask, place the lithium in the
conical flask and immediately replace the stopper to ensure no
hydrogen gas escapes.

6. Collect the hydrogen gas in the measuring cylinder and record the
final volume.

Results

1st Attempt

2nd Attempt

3rd Attempt

Weight of Lithium

0.040g

0.044g

0.042g

Amount of hydrogen collected

50 cm

76 cm

78 cm

Calculations

1st Attempt -

76 cm 0.00317 0.00317 X 2
=0.0063

24000 cm

0.044 6.98

0.0063

2nd Attempt –

78 cm 0.00325 0.00325 X 2 = 0.0065

24000 cm

0.042 6.462

0.0065

Average Titre –
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