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Question 1 of 3

A person gargles 15 ml of Compound Sodium Chloride Mouthwash BP 1988 containing 1.5 % w/v Sodium Chloride. How many milligrams of Sodium Chloride did the the person gargle with?

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mg
The person gargled with 225 mg of Sodium Chloride.
EITHER
 mass of solute = % w/v x volume of product    g
100
mass of Sodium Chloride = 1.5 x    15      g
100
mass of Sodium Chloride = 0.225 g = 225 mg
OR
 1.5 % w/v Sodium Chloride means that:
100 ml of mouthwash contains 1.5 g of Sodium Chloride
Thus: 15 ml of mouthwash contains    15    x 1.5 g of Sodium Chloride
100
15 ml of mouthwash contains 0.225 g ie 225 mg of Sodium Chloride

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Question 2 of 3

Methadone Linctus BP 1988 contains 0.04 % w/v Methadone Hydrochloride. 1.8 litres of the linctus needs to be prepared. How many grams of Methadone Hydrochloride need to be weighed out?

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g
0.72 g of Methadone Hydrochloride need to be weighed out.
EITHER
Convert volume from litres to millilitres: volume = 1.8 l = 1800 ml
mass of solute = % w/v x volume of product    g
100
mass of Methadone Hydrochloride = 0.04 x 1800   g
100
mass of Methadone Hydrochloride = 0.72 g
OR
 0.04 % w/v Methadone Hydrochloride means that:
100 ml of linctus contains 0.04 g of Methadone Hydrochloride
Thus: 1800 ml of linctus contains 1800 x 0.04 g of Methadone Hydrochloride
100
1800 ml of linctus contains 0.72 g of Methadone Hydrochloride

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Question 3 of 3

A runner sprays 1.5 ml of Athlete's Foot Spray onto his foot. If the spray contains 1 % w/v Tolnaftate BP, how many milligrams of Tolnaftate did the runner spray onto his foot?

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mg
The runner sprayed 15 mg of Tolnaftate onto his foot.
EITHER
 mass of solute = % w/v x volume of product    g
100
mass of Tolnaftate = 1 x    1.5      g
100
mass of Tolnaftate = 0.015 g = 15 mg
OR
 1 % w/v Tolnaftate means that:
100 ml of spray contains 1 g of Tolnaftate
Thus: 1.5 ml of spray contains    1.5    x 1 g of Tolnaftate
100
1.5 ml of spray contains 0.015 g = 15 mg of Tolnaftate

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