Molarity Quiz: Practice Molarity Calculations Test

Study Notes

Molar Concentration (Molarity)

Molarity is the number of moles of a solute in 1 liter of solution.
It is calculated by dividing the number of moles of solute by the volume of solution in liters.
Example: Calculate the molar concentration of ethanol in an aqueous solution that contains 2.30g of C2H5OH (46g/mol) in 3.50 L of solution.

Molarity Problems

Calculate the molar concentration of a solution of NaOH (40g/mol) in which 0.4g NaOH dissolved in 500ml solution.
Calculate the molarity of a solution of sodium metal (23g/mol) in which 0.115g of pure sodium metal was dissolved in 500ml distilled water.

Normal Concentration (Normality)

Normality is the number of equivalents of solute that is contained in 1 L of solution.
For acids, normality is calculated by dividing the number of moles of solute by the number of replaceable H+ ions.
For bases, normality is calculated by dividing the number of moles of solute by the number of replaceable OH- ions.
For salts, normality is calculated by dividing the number of moles of solute by the total number of positive or negative charge.
Example: Find the normality of H2SO4 (98g/mol) having 49g of H2SO4 present in 500ml of solution.

Percent Concentration

Percent concentration is a way to express concentrations in terms of percent (parts per hundred).
There are three common methods: weight percent, volume percent, and weight to volume percent.
Weight percent is often used to express the concentration of commercial aqueous reagents.
Volume percent is commonly used to specify the concentration of a solution prepared by diluting a pure liquid compound with another liquid.
Weight to volume percent is often used to indicate the composition of dilute aqueous solutions of solid reagents.
Example: A solution was prepared by dissolving 2.45 g of AgNO3 in sufficient water to give 40 mL, calculate the w/v percent of AgNO3.

Parts per Million (ppm)

Parts per million is a convenient way to express concentration for very dilute solutions.
A handy rule is to remember that for dilute aqueous solutions whose densities are approximately 1.00 g/mL, 1 ppm = 1.00 mg/L.

Dilution

When a solution is diluted, the normality of the diluted solution is decreased.
Example: A 20 ml of 10 N HCl are diluted with distilled water to form one liter of the solution, what is the normality of the diluted solution?

Description

Test your understanding of molarity with these practice questions. Calculate the molar concentration of solutes in different solutions using the given data. Perfect for students studying chemistry or anyone wanting to improve their knowledge of molarity calculations.