If 25.5g of sodium thiosulphate was dissolved in 40g of distilled water at 25°C, I). Calculate the solubility of the solute in mol/dm^3
II). Calculate the solubility in g/dm^3

Formula: Na2S2O3

we get solubility.

Divide the mass of the compound by the mass of the solvent and then multiply by 100 g to calculate the solubility in g/100g .

Solution given:

mass of sodium thiosulphate [m1]=25.5g

mass of water [m2]=40g

at temperature [t]=25°C

we have

solubility in g/dm^3 :

solubility in g/dm^3 :63.75g/dm³

now

solubility of the solute in mol/dm^3=:63.75g/dm³/178=0.4 mol/dm³

the ratio of the conjugate base to the acid required to attain the desired ph.