Calculation of Normality and Molarity of K2Cr2O7

Given:
- Volume of K2Cr2O7 solution = 50 ml
- Mass of Mohr's salt (FeSO4.(NH4)2SO4.6H2O) = 0.392 grams

Step 1: Convert the mass of Mohr's salt to moles
To find the number of moles of Mohr's salt, we need to divide the given mass by its molar mass. The molar mass of Mohr's salt can be calculated as follows:

Molar mass of FeSO4.(NH4)2SO4.6H2O = (1 * atomic mass of Fe) + (1 * atomic mass of S) + (4 * atomic mass of O) + (2 * atomic mass of N) + (8 * atomic mass of H) + (2 * atomic mass of S) + (24 * atomic mass of O)
= (1 * 55.85 g/mol) + (1 * 32.07 g/mol) + (4 * 16.00 g/mol) + (2 * 14.01 g/mol) + (8 * 1.01 g/mol) + (2 * 32.07 g/mol) + (24 * 16.00 g/mol)
= 392.14 g/mol

Now, we can calculate the number of moles of Mohr's salt using the formula:
Number of moles = Mass / Molar mass
Number of moles = 0.392 g / 392.14 g/mol
Number of moles = 0.001 mol

Step 2: Determine the moles of K2Cr2O7 using the balanced equation
The balanced equation for the reaction between K2Cr2O7 and Mohr's salt in acidic medium is:

6FeSO4.(NH4)2SO4.6H2O + K2Cr2O7 + 7H2SO4 → 3Fe2(SO4)3 + Cr2(SO4)3 + K2SO4 + 14H2O + 6(NH4)2SO4

From the balanced equation, we can see that the ratio of K2Cr2O7 to Mohr's salt is 1:6. Therefore, the number of moles of K2Cr2O7 required can be calculated as follows:

Number of moles of K2Cr2O7 = 0.001 mol * 1/6
Number of moles of K2Cr2O7 = 0.0001667 mol

Step 3: Calculate the Normality of K2Cr2O7
Normality is defined as the number of gram equivalents of solute per liter of solution. In this case, K2Cr2O7 is the solute.

The gram equivalent weight of K2Cr2O7 can be calculated by dividing its molar mass by its change in oxidation state per mole of electrons transferred. In the case of K2Cr2O7, the change in oxidation state is 6, as it undergoes a 6-electron reduction in the reaction.

Gram equivalent weight of K2Cr2O7 = M