A clinical sample was analysed for potassium content by flame emission spectroscopy. 1 ml of the sample was diluted and divided to make two 10 ml aliquots. The emission signal (in arbitrary units) of the first was recorded as 35.0. One hundred microliters of 0.025 mol dm3 KCl solution was then added to the second 10 ml aliquot, after which its emission signal increased to a reading of 59.0. Calculate the concentration of K+ in the original sample in units of mol dm3.

7. A clinical sample was analysed for potassium content by flame emission spectroscopy. 1 ml of the sample was diluted and divided to make two 10 ml aliquots. The emission signal (in arbitrary units) of the first was recorded as 35.0. One hundred microliters of 0.025 mol dm-3 KCl solution was then added to the second 10 ml aliquot, after which its emission signal increased to a reading of 59.0. Calculate the concentration of K+ in the original sample in units of mol dm-?. (6 marks)