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(a) Calculate the pH of the buffer solution (generated from 0.2 hosphate HPO (we

ID: 1039593 • Letter: #

Question

(a) Calculate the pH of the buffer solution (generated from 0.2 hosphate HPO (weak acid) and 0.7 M phosphate (conijugate 10-13 for hydrogen phosphate/phosphate. from 0.2 M hydrogen (5 pts) (b) Calculate the pH of the buffer solution from part (a) after 02 mole of H:SOsis dissolved into that solution. Did the pH change? 15. (5 pts) Calculate AG Pracin for the following reaction at the standard temperature kl/mol; AG H20 -237.1 kJ/mo 15. (5 pts) Ca K (25°C). Is the reaction spontaneous? 0 (a)-> H20(I) + CO2(g)

Explanation / Answer

14)

a)

Ka = 3.6 x 10^-13

pKa = -log Ka

pKa = 12.4

pH = pKa + log [PO4-3 / HPO4 -2]

pH = 12.4 + log (0.7/ 0.2)

pH = 12.9

b)

moles of H+ = 0.2 x 2 = 0.4

pH = pKa + log [PO4-3 - C / HPO4 -2 + C]

pH = 12.4 + log (0.7-0.4 / 0.2 + 0.4)

pH = 12.1

yes the pH will change . from 12.9 to 12.1