What ratio does molarity express?

M = # moles/liter of solution.

Molarity expresses the ratio between the amount of solute and the volume of the solution. It is defined as the number of moles of solute per liter of solution (mol/L). In mathematical terms, the molarity (M) is calculated by dividing the number of moles of solute (n) by the volume of the solution in liters (V):

Molarity (M) = moles of solute (n) / volume of solution (V in L)

To determine the molarity, you need to know the number of moles of solute present in the solution and the volume of the solution in liters. The number of moles can be calculated using the formula:

Moles of solute (n) = mass of solute (m) / molar mass of solute (M)

Where the mass of the solute is measured in grams and the molar mass is expressed in grams per mole. To find the molar mass of a compound, you sum up the atomic masses of all the atoms present in the formula unit.

Once you have determined the moles of solute and the volume of the solution, you can divide the moles by the volume in liters to obtain the molarity. Remember to use consistent units of measurements throughout the calculations.

For example, if you have 0.5 moles of solute dissolved in 1 liter of solution, the molarity would be:

Molarity (M) = 0.5 moles / 1 liter
= 0.5 M