Question

Describe how to make the following solutions, including calculations for masses of solid reactants:

a. A 0.50 M sodium sulfate solution.

b. A 0.10 M buffer at pH 8.2.

You will need to select an appropriate reagent with which to make this buffer

Answer 1

Answer: According to the question ,

a] We have given the 0.50M Sodium sulfate solution means it has contain 0.5 mol in 1 litter .

and we know that , mol = mass / molar mass

0.5 * 142.04 = mass = 71.02 g of Sodium sulfate is required to prepare a 0.50 M solution .

this is all about the first part .

b} Here we have to use the Hendor's equations

Ph = Pka + Log [salt] / [Acid]

hence here we have the vlaue of PH = 8.2

[Note : the values of Pka is required and it is generally given in questions ]

Let consider the compound is tris base and having the value of Kb = 5.7

Hence POH = 14 - Ph = 14-8.2 = 5.8

POh = Pkb + log [salt] / [base]

we get , the relaton between [salt]/ [base]

and According to question we have the realtion =[salt ] + [base] = 8.2

Hence by using it generally we find out the amount of salt is form or the amount of acid is used to prepare this type of buffer .

I hope you understand it . Thank you