Calculate the equivalent mass of K2Cr2O7 in acid medium by Oxidation number method.

To calculate the equivalent mass of K2Cr2O7 in acid medium using the oxidation number method, follow these steps:

Step 1: Write down the balanced chemical equation for the reaction involving K2Cr2O7 in acid medium. For example, if we consider the reaction with sulfuric acid (H2SO4), the equation would be:

K2Cr2O7 + 4H2SO4 → K2SO4 + Cr2(SO4)3 + 4H2O

Step 2: Identify the element undergoing oxidation and reduction in the reaction. In this case, chromium (Cr) is being reduced from +6 to +3 oxidation state, while sulfur (S) is being oxidized from +6 to +4 oxidation state.

Step 3: Determine the change in oxidation number for the element undergoing oxidation and reduction. In this case, the change in oxidation number for chromium is -3, while the change in oxidation number for sulfur is +2.

Step 4: Calculate the equivalent mass of K2Cr2O7 using the formula:

Equivalent mass = Molecular weight / Change in oxidation number

The molecular weight of K2Cr2O7 is 294.19 g/mol.

For chromium (Cr): Equivalent mass of Cr = 294.19 g/mol / (-3) = -98.06 g/mol

For sulfur (S): Equivalent mass of S = 294.19 g/mol / (+2) = 147.10 g/mol

Step 5: The equivalent mass of K2Cr2O7 in acid medium is the sum of the equivalent masses of chromium and sulfur:

Equivalent mass of K2Cr2O7 = Equivalent mass of Cr + Equivalent mass of S Equivalent mass of K2Cr2O7 = -98.06 g/mol + 147.10 g/mol Equivalent mass of K2Cr2O7 = 49.04 g/mol

Therefore, the equivalent mass of K2Cr2O7 in acid medium, calculated using the oxidation number method, is 49.04 g/mol.