25g of a sample of ferrous sulphate was dissolved in water containing dilute h2s04 and the volume made up to one litre. 25ml of this solution required 20ml of N/10 kmn04 solution for complete oxidation. Calculate the percentage of f2s047h20 in the sample The right answer 88.96%

0.02 x 0.1 = 0.002
0.002 x 1000ml x 293g/mol / 25ml = 23.44
23.44 / 25g x 100% = 93.76%

To calculate the percentage of FeSO4•7H2O in the sample, we need to understand the reaction that is taking place between FeSO4 and KMnO4.

The balanced chemical equation for the reaction between FeSO4 and KMnO4 is:
5FeSO4 + 2KMnO4 + 8H2SO4 → 5Fe2(SO4)3 + 2MnSO4 + K2SO4 + 8H2O

From the equation, we can see that 5 moles of FeSO4 reacts with 2 moles of KMnO4. This means that the ratio of FeSO4 to KMnO4 is 5:2.

Here is how we can calculate the percentage of FeSO4•7H2O in the sample:

1. Calculate the number of moles of KMnO4 used.
The N/10 KMnO4 solution means that one liter of the solution contains one-tenth of a mole of KMnO4.
So, 20 mL (0.020 L) of the N/10 KMnO4 solution contains:
(0.020 L) x (1/10 mol/L) = 0.002 mol of KMnO4

2. Calculate the number of moles of FeSO4 in the sample.
As mentioned earlier, the ratio of FeSO4 to KMnO4 in the reaction is 5:2. Therefore, the number of moles of FeSO4 in the sample is:
(0.002 mol KMnO4) x (5 mol FeSO4 / 2 mol KMnO4) = 0.005 mol FeSO4

3. Determine the molar mass of FeSO4•7H2O.
The molar mass of FeSO4 is 151.91 g/mol. The molar mass of water (H2O) is 18.02 g/mol.
So, the molar mass of FeSO4•7H2O is:
(151.91 g/mol) + (7 x 18.02 g/mol) = 278.97 g/mol

4. Calculate the mass of FeSO4•7H2O in the sample.
The mass of FeSO4•7H2O in the sample is:
(0.005 mol) x (278.97 g/mol) = 1.39485 g

5. Calculate the percentage of FeSO4•7H2O in the sample.
The mass of the sample is given as 25 g.
So, the percentage of FeSO4•7H2O in the sample is:
(1.39485 g / 25 g) x 100% = 5.5794%

Note: The calculation you provided in your question seems to have made an error. The correct calculation should yield a percentage of approximately 5.58%, which is significantly lower than the given correct answer of 88.96%. Therefore, please ensure that the question and the given correct answer are accurate.