w1 example 4 answers
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4a 1ml of water occupies a volume of 1cm3. How many
litres will 5cm3 of water occupy?
4a • Convert 1ml into litres:
4a • Convert 1ml into litres:
1ml = 0.001L
4a • Convert 1ml into litres:
1ml = 0.001L
• Multiply this by the size of the sample:
4a • Convert 1ml into litres:
1ml = 0.001L
• Multiply this by the size of the sample:
5cm3 = 5ml = 0.001L x 5 = 𝟓 𝐱 𝟏𝟎−𝟑𝐋
4b There are 1.4 x 1021L of water in the ocean. What is
this in cubic metres?
4b • Work out the conversion between cm3 and m3:
4b • Work out the conversion between cm3 and m3:
1cm = 0.01m
4b • Work out the conversion between cm3 and m3:
1cm = 0.01m
1cm3 = cm x cm x cm = 0.01 x 0.01 x 0.01 m3 = 1 x 10−6m3
4b • Work out the conversion between cm3 and m3:
1cm = 0.01m
1cm3 = cm x cm x cm = 0.01 x 0.01 x 0.01 m3 = 1 x 10−6m3
• Work out the conversion between 1L and 1m3:
4b • Work out the conversion between cm3 and m3:
1cm = 0.01m
1cm3 = cm x cm x cm = 0.01 x 0.01 x 0.01 m3 = 1 x 10−6m3
• Work out the conversion between 1L and 1m3:
1ml = 1cm3
4b • Work out the conversion between cm3 and m3:
1cm = 0.01m
1cm3 = cm x cm x cm = 0.01 x 0.01 x 0.01 m3 = 1 x 10−6m3
• Work out the conversion between 1L and 1m3:
1ml = 1cm3
1 x 10−3L = 1 x 10−6m3
4b • Work out the conversion between cm3 and m3:
1cm = 0.01m
1cm3 = cm x cm x cm = 0.01 x 0.01 x 0.01 m3 = 1 x 10−6m3
• Work out the conversion between 1L and 1m3:
1ml = 1cm3
1 x 10−3L = 1 x 10−6m3
1L = 1 x 10−3m3
4b • Work out the conversion between cm3 and m3:
1cm = 0.01m
1cm3 = cm x cm x cm = 0.01 x 0.01 x 0.01 m3 = 1 x 10−6m3
• Work out the conversion between 1L and 1m3:
1ml = 1cm3
1 x 10−3L = 1 x 10−6m3
1L = 1 x 10−3m3
• Multiply by the volume of the ocean:
4b • Work out the conversion between cm3 and m3:
1cm = 0.01m
1cm3 = cm x cm x cm = 0.01 x 0.01 x 0.01 m3 = 1 x 10−6m3
• Work out the conversion between 1L and 1m3:
1ml = 1cm3
1 x 10−3L = 1 x 10−6m3
1L = 1 x 10−3m3
• Multiply by the volume of the ocean:
1.4 x 1021L = 1.4 x 1021 x 10−3 m3 = 𝟏. 𝟒 𝐱 𝟏𝟎𝟏𝟖𝐦𝟑
4c Seawater contains about 142mgL-1of bicarbonate.
How many grams of bicarbonate will there be in a 2m3
sample of seawater?
4c • Convert 142 mgL-1 into 142 mgm-3:
4c • Convert 142 mgL-1 into 142 mgm-3:
1𝐿 = 1 𝑥 10−3𝑚3
4c • Convert 142 mgL-1 into 142 mgm-3:
1𝐿 = 1 𝑥 10−3𝑚3
1
1𝐿−1 =
1
10−3𝑚−3
4c • Convert 142 mgL-1 into 142 mgm-3:
1𝐿 = 1 𝑥 10−3𝑚3
1
1𝐿−1 =
1
10−3𝑚−3
1𝐿−1 = 103𝑚−3
4c • Convert 142 mgL-1 into 142 mgm-3:
1𝐿 = 1 𝑥 10−3𝑚3
1
1𝐿−1 =
1
10−3𝑚−3
1𝐿−1 = 103𝑚−3
142𝑚𝑔𝐿−1 = 142 𝑥 103𝑚𝑔𝑚−3 = 1.42 𝑥 105𝑚𝑔𝑚−3
4c • Convert 142 mgL-1 into 142 mgm-3:
1𝐿 = 1 𝑥 10−3𝑚3
1
1𝐿−1 =
1
10−3𝑚−3
1𝐿−1 = 103𝑚−3
142𝑚𝑔𝐿−1 = 142 𝑥 103𝑚𝑔𝑚−3 = 1.42 𝑥 105𝑚𝑔𝑚−3
• Multiply by the sample size and convert mg to g:
4c • Convert 142 mgL-1 into 142 mgm-3:
1𝐿 = 1 𝑥 10−3𝑚3
1
1𝐿−1 =
1
10−3𝑚−3
1𝐿−1 = 103𝑚−3
142𝑚𝑔𝐿−1 = 142 𝑥 103𝑚𝑔𝑚−3 = 1.42 𝑥 105𝑚𝑔𝑚−3
• Multiply by the sample size and convert mg to g:
1.42 𝑥 105𝑚𝑔𝑚−3 𝑥 2𝑚3 = 2.84 𝑥 105𝑚𝑔
4c • Convert 142 mgL-1 into 142 mgm-3:
1𝐿 = 1 𝑥 10−3𝑚3
1
1𝐿−1 =
1
10−3𝑚−3
1𝐿−1 = 103𝑚−3
142𝑚𝑔𝐿−1 = 142 𝑥 103𝑚𝑔𝑚−3 = 1.42 𝑥 105𝑚𝑔𝑚−3
• Multiply by the sample size and convert mg to g:
1.42 𝑥 105𝑚𝑔𝑚−3 𝑥 2𝑚3 = 2.84 𝑥 105𝑚𝑔
2.84 𝑥 105 𝑥 10−3 = 𝟐𝟖𝟒𝒈
4d There is approximately 1.81 x 1021g of magnesium in
the entire ocean. For any sample of seawater,
calculate the magnesium content in molL-1.
4d • Calculate the number of moles of Mg in the ocean:
4d • Calculate the number of moles of Mg in the ocean:
1 mole Mg = 24.305g
4d • Calculate the number of moles of Mg in the ocean:
1 mole Mg = 24.305g
1.81 x 1021
24.305= 7.45 x 1019mol Mg
4d • Calculate the number of moles of Mg in the ocean:
1 mole Mg = 24.305g
1.81 x 1021
24.305= 7.45 x 1019mol Mg
• Use the volume of the ocean to work out the overall
concentration of Mg in seawater:
4d • Calculate the number of moles of Mg in the ocean:
1 mole Mg = 24.305g
1.81 x 1021
24.305= 7.45 x 1019mol Mg
• Use the volume of the ocean to work out the overall
concentration of Mg in seawater:
7.45 x 1019mol Mg
1.4 x 1021L= 𝟎. 𝟎𝟓𝟑𝐦𝐨𝐥𝐋−𝟏
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