Definition of Molarity and Normality
Molarity and normality are two different concentration units used in chemistry.

Molarity (M) is defined as the number of moles of solute per liter of solution.

Normality (N) is defined as the number of gram equivalents of solute per liter of solution.

Calculation of Normality from Molarity
To calculate the normality of a solution, we need to know the type of reaction that the solute undergoes in the solution. For example, if a solute undergoes a one-to-one reaction, then its normality is the same as its molarity. However, if the solute undergoes a multiple reaction, then its normality is equal to its molarity multiplied by the number of equivalents per mole.

In the case of K2Cr2O7, the reaction is a one-to-one reaction. Therefore, its normality is equal to its molarity.

Calculation of Normality of K2Cr2O7 Solution
Given that the molarity of K2Cr2O7 solution is 0.5 M, we can calculate its normality using the following formula:

Normality = Molarity × Number of equivalents per mole

The number of equivalents per mole of K2Cr2O7 is equal to the number of moles of electrons that the compound can donate or accept in a reaction. In the case of K2Cr2O7, the number of equivalents per mole is equal to 6.

Therefore, the normality of the K2Cr2O7 solution is:

Normality = 0.5 M × 6 equivalents/mole = 3 N

Therefore, the normality value of the K2Cr2O7 solution is 3.