WCH11 October 2022

12​​ A mass of 4.08g of hydrated copper (II) sulfate, CuSO4∙5H2O, was dissolved in deionized water to form 250cm3​​ of solution. What is the concentration of the copper (II) sulfate solution formed, in mol dm–3?​​ 

A​​  0.0163​​ 

B​​  0.0256​​ 

C​​  0.0654​​ 

D​​  0.102

ANSWER

C​​  0.0654​​ 

Analysis of Option/Explanation

Step 1: finding moles by ratio method

Mr​​ of CuSO4∙5H2O = 250g

1 moles of CuSO4∙5H2O= 250 g

X moles of CuSO4∙5H2O = 4.08 g

Hence,​​ 

X moles = 0.016346 moles

Step 2: finding volume

0.016346 moles of CuSO4∙5H2O dissolved in = 250cm3

X moles dissolved = 1000cm3

Therefore,

=1000250×0.016346

=0.0654 moles

Therefore,​​ option C​​ is the correct answer.