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Use the 10^-3pC-pH diagram for closed carbonate system to find the pH for a solu

ID: 1057867 • Letter: U

Question

Use the 10^-3pC-pH diagram for closed carbonate system to find the pH for a solution containing 10^-3 M Na_2CO_3, but close to the atmosphere. Use the pC-pH diagram for open carbonate system to find the pH for a solution containing 10^-5 M Na_2CO_3, that equilibrium with atmosphere. Titration experiment is conduct for a 50 ml water sample to test its alkalinity. The initial pH of the water sample is 9.0, HCI (0.02 mol/l) is used to titrate the water sample. 4.6 mL HCI was used to reach phenolphthalein end point, and 8.8 ml was used to reach methyl orange end point, calculate the concentration of OH^-, CO_3^2-, and HCO_3^-, and what is the total alkalinity of the water sample in mg/L as CaCO_3? How many moles of AgCl can dissolve in a solution contains 0.001 mol/L NaCl, given the K_sp, for AgCl is 10^-10, neglect the ionic strength effect. How many moles of AgCl can dissolve in 0.1 mol/L NaNO_3 solution if consider the ionic strength effect.

Explanation / Answer

Q.4: Givnen [Cl-(aq)] = 0.001 M

The chemical reaction for the dissociation of AgCl is

AgCl(s) + H2O <----- > Ag+(aq) + Cl-(aq) : Ksp = 10-10  

  Ksp = 10-10 = [Ag+(aq)]x[Cl-(aq)]

=> 10-10 = [Ag+(aq)]x0.001

=> [Ag+(aq)] =  10-10 / 0.001 = 10-7 mol/L or 10-7 M (answer)