Citric acid reacts with sodium hydroxide according to the following chemical equation:
\( \ce{C6H8O7(aq) + 3NaOH(aq) -> Na3C6H5O7(aq) + 3H2O(l)} \)
Various volumes of 1.0 mol L¯1 citric acid solution were mixed with 8.0 mL of a sodium hydroxide solution of unknown concentration and sufficient deionised water added to make the total volume of the resulting solution 14.0 mL. The change in temperature of each solution was measured.
The data are given in the table.
By graphing the data in the table and performing relevant calculations, determine the concentration of the sodium hydroxide solution. (7 marks)
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`text{n(citric acid)} = c xx V = (1.0) xx (2.4 xx 10^(−3)) = 2.4 xx 10^(−3)\ text{mol}`
`text{n(sodium hydroxide)} = 3 xx (2.4 xx 10^(−3)) = 7.2 xx 10^(−3)\ text{mol}`
`text{[sodium hydroxide]} = [7.2 xx 10^(−3)] / [8.0 xx 10^(−3)] = 0.90\ text{mol L}^(–1)`
`text{n(citric acid)} = c xx V = (1.0) xx (2.4 xx 10^(−3)) = 2.4 xx 10^(−3)\ text{mol}`
`text{n(sodium hydroxide)} = 3 xx (2.4 xx 10^(−3)) = 7.2 xx 10^(−3)\ text{mol}`
`text{[sodium hydroxide]} = [7.2 xx 10^(−3)] / [8.0 xx 10^(−3)] = 0.90\ text{mol L}^(–1)`