You had learnt about "solubility product" (K_sp) in First Year Chemistry (see page 124 of textbook by Harris). Given the K_sp of calcium phosphate is 1.2 × 10^-29,

(i) write down an appropriate chemical equation that shows the solubility of calcium phosphate.

(ii) write down an expression for K_sp of calcium phosphate based on your answer in

(iii) calculate the solubility of calcium phosphate.

(iv) if the standard deviation of this K_sp is 0.1 × 10^-29, what is the standard deviation of the solubility of calcium phosphate calculated in (iii)?

(b) The Nernst equation, applied in potentiometric analysis, is expressed as

E=E^o +^RTlogeC nF

where E is the measured potential of the electrode, E° is the standard electrode potential for the ion to be determine, T is the absolute temperature, n is the number of electrons involved in the half-cell concerned, C is the concentration of the ion, R is the gas constant and F is the Faraday constant.

Obtain an expression for the relative standard deviation of the concentration, assuming that T = 298 K and is without error. Then, calculate the value of the relative standard deviation if n = 1 and the standard deviation of E is 0.001 V. You can also assume E° is error free.