I need the answers for these questions please !!! Find the equilibrium pH value

Question

I need the answers for these questions please !!!

Find the equilibrium pH value if copper ion (Cu^2+) concentration in water is 1.2 mg/L. The copper ion is dissolved from Cu(OH)_2. Calculate the equilibrium concentration of dissolved oxygen in mg/L in 10degree C water (a) at ms1 (mean sea level), and (b) at 600 m elevation. Methanol (CH_3OH) is a possible alternative automobile fuel with a density of 6.0 lb/gal and a standard enthalpy value H degree = -250 kJ/mol. Find its higher heating value (HHV) and net heat of combustion (LHV) in kJ/mol and in Btu/gal.

Explanation / Answer

Cu(OH)2 (aq) -------> Cu+2 (aq) + 2 OH- (aq)

[Cu2+] = 1.2 mg/L = (1.2 mg * 1 g/1000mg ) * (1 mol Cu/ 63.55 g Cu) * 1/L = 1.89*10-5 mol/L

[OH-] = 1.89*10-5 mol/L Cu2+ * 2 mol OH- / 1 mol Cu2+ = 3.78*10-5 mol/L OH-

pOH = - log [OH-] = - log (3.78*10-5 mol/L) = 4.42

pH + pOH = 14.00

pH = 14.00-4.42 = 9.58

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