Using the same 5 cm3-total dilution series as Table 1.1 (1 cm3 stock + 4 cm3 water = 0.001 mol/dm3, up to 3 cm3 stock + 2 cm3 water = 0.003 mol/dm3), how many cm3 of the 0.005 mol/dm3 glucose stock and how many cm3 of distilled water are needed to make the 0.005 mol/dm3 standard itself?

Model answer

5 cm3 stock, 0 cm3 water

Also accepted: 5 and 0, 5cm3 glucose, 0cm3 water, 5 cm3 stock and 0 cm3 water

Explanation

Making the standard at the same concentration as the stock needs no dilution: 5 cm3 of stock and 0 cm3 of water.

Derived from ZIMSEC Biology 9190/4 Paper 4, November 2004, Q1

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