What is the calculation used to deduce the molarity of iodine from its mass?

• A. Mass (g) / Molecular Weight (g/mol)
• B. Mole of solute / Volume of solution (L)
• C. Mass (g) / Volume (mL)
• D. Temperature (K) x Gas Constant (J/mol K)

Answer: (A)

To determine the molarity of a solution, one must first convert the mass of the solute (in this case, iodine) into moles. This conversion is achieved by using the molecular weight (also known as molar mass) of the solute. The formula for calculating the number of moles from mass is:

Moles = Mass (g) / Molecular Weight (g/mol)

Once the number of moles of iodine is known, molarity can then be calculated using the formula:

Molarity (M) = Moles of solute / Volume of solution (L)

The initial step of determining the number of moles by dividing mass by molecular weight is essential and lays the foundation for finding the molarity. Therefore, the calculation that needs to be performed to deduce the molarity begins with this ratio of mass to molecular weight.

The other options presented are not direct calculations for deducing molarity. For example, using moles divided by volume is the final step in calculating molarity, but it doesn’t address the initial conversion from mass. The temperature and gas constant option relates to gas laws and does not pertain to the determination of molarity in this context.