Calculate the pH of the following solutions : (a) 2 g of TlOH dissolved in water to give 2 litre of the solution (b) 0.3 g of Ca(OH)_(2) dissolved in water to give 500 mL of the solution (c) 0.3 g of NaOH dissolved in water to give 200 mL of the solution (d) 1 mL of 13.6 M HCl is diluted with water to give 1 litre of the solution.

Calculate the pH of the following solutions : (a) 2 g of TlOH dissolve

1.	Calculate the pH of the following solutions : (a) 2 g of TlOH dissolved in water to give 2 litre of the solution (b) 0.3 g of Ca(OH)_(2) dissolved in water to give 500 mL of the solution (c) 0.3 g of NaOH dissolved in water to give 200 mL of the solution (d) 1 mL of 13.6 M HCl is diluted with water to give 1 litre of the solution.
Answer» Solution :(a) Molar conc. Of TLOH `= (2G)/((204+16+1)g "MOL"^(-1))xx(1)/(2L)=4.52xx10^(-3)M` `:. [OH^(-)]=[TlOH]=4.52xx10^(-3)M` `[H^(+)]=10^(-14)//(4.52xx10^(-3))=2.21xx10^(-12)M` `pH = - log (2.21xx10^(-12))=12-(0.3424)=11.66` (b) Molar conc. of `CA(OH)_(2) = (0.3 g)/((40+34) g "mol"^(-1))xx(1)/(0.5L)=8.11xx10^(-3)M` `Ca(OH)_(2) rarr Ca^(2+)+ 2 OH^(-)` `:. [OH^(-)]=2[Ca(OH)_(2)]=2xx(8.11xx10^(-3))M = 16.22xx10^(-3)M` `pOH = - log (16.22xx10^(-3))=3-1.2101=1.79` `pH = 14-1.79=12.21` (C) Molar conc. of NaOH `=(0.3 g)/(40 g "mol"^(-1))xx(0.2L)=3.75xx10^(-2)M` `[OH^(-)]=3.75xx10^(-2)M` `pOH = - log (3.75xx10^(-2))=2-0.0574 = 1.43 :. pH = 14 - 1.43 = 12.57` (d) `M_(1)V_(1) = M_(2)V_(2) :. 13.6 M xx 1 mL = M_(2) xx 1000mL :. M_(2) = 1.36xx10^(-2)M` `[H^(+)]=[HCl]=1.36xx10^(-2)M, pH = - log (1.36xx10^(-2))=2-0.1335 ~= 1.87`