A solution is prepared by dissolving 30.05 g of ammonium dichromate in water and diluting it to 500 mL. What is the molarity of the solution?

Molarity(M) = 0.24M in (NH₄)₂Cr₂O₇.

Explanation:

By definition a solution is a homogeneous physical mixture of two substances, a solute (item in least amount) and solvent (item in greatest amount). Typically the solution is generally described in terms of the concentration of solute in solution (solute + solvent). Concentration is, by definition amount of solute divided the volume of solution. That is ...

concentration = amount solute / volume of solution

There are numerous unit expressions of concentration such as lbs/gal, lbs/ft³, grams/ml and molarity(M). For this problem, Molar Concentration following concentration definition is ...

Molarity(M) = moles solute / volume of solution in liters

moles of (NH₄)₂Cr₂O₇ = 30.05g/252.07g/mole = 0.12mole

Volume of Solution = 500ml = 0.500Liters

∴Molarity = [(NH₄)₂Cr₂O₇] = 0.12 moles / 0.500L = 0.24M in (NH₄)₂Cr₂O₇.

Note => the brackets [ ] around the formula (NH₄)₂Cr₂O₇ indicates Molar concentration.