Quiz – Concentration and dilutions

If you are handling solutions, being able to complete calculations related to concentrations and dilutions is critical. Test your ability to do these with a quiz.

Your turn – concentration and dilutions

1. Determine the volume (in \(\textrm{mL}\)) of ethanol required to prepare \(80\textrm{ mL}\) of a \(70.0\%(v/v)\) solution.

2. A solution contains \(3.56\textrm{ g}\) of sodium chloride dissolved in a final volume of \(25.0\textrm{ mL}\). Calculate the percent concentration of sodium chloride in \(\%(m/v)\).

3. When \(2.50\textrm{ g}\) of \(\ce{LiBr}\) is dissolved in \(25.0\textrm{ g}\) of water, it gives a \(10.0\%(m/m)\) \(\ce{LiBr}\) solution. Calculate the mass of \(\ce{LiBr}\) present in \(15.0\textrm{ g}\) of the same solution.

4. Calculate the mass in grams of sodium chloride required to prepare \(500\textrm{ mL}\) of a \(2.0\%(m/v)\) sodium chloride solution.

5. Brass is a metal alloy composed of \(\ce{Cu}\) and \(\ce{Zn}\). Usually, \(\ce{Cu}\) accounts for \(60.0\%(m/m)\) of the composition. Determine the mass of brass that would contain \(48.3\textrm{ g}\) of \(\ce{Cu}\).

6. Calculate the quantities of solute or solvent required to prepare the following solutions:
1. the mass of \(\ce{K2SO4}\) required to prepare \(48.0\textrm{ g}\) of a \(3.00\%(m/m)\) \(\ce{K2SO4}\) solution

Answer

\(1.44\textrm{ g}\)

2. the volume of acetone required to prepare \(1.0\textrm{ L}\) of a \(70.0\%(v/v)\) acetone solution

Answer

\(700\textrm{ mL}\) or \(0.70\textrm{ L}\)

3. the mass of sodium azide required to prepare \(500\textrm{ mL}\) of \(1.50\%(m/v)\) sodium azide solution.

Answer

\(7.50\textrm{ g}\)

7. The maximum chlorine concentration allowed in drinking water is \(4.0\textrm{ mg}\) per \(1.0\textrm{ L}\) (\(1.0\textrm{ kg}\)).
1. Express the maximum chlorine concentration in drinking water in ppm.

Answer

\(4.0\textrm{ ppm}\)

2. Calculate the maximum mass of chlorine allowed in \(240\textrm{ mL}\) or \(240\textrm{ g}\) of drinking water.

Answer

\(9.6\times10^{-4}\textrm{ g}\) or \(0.96\textrm{ mg}\)

8. Calculate the molarity of the following solutions:
1. \(3.0\textrm{ mol}\) of silver nitrate in \(0.50\textrm{ L}\) of solution

Answer

\(6.0\textrm{M}\)

2. \(0.0625\textrm{ mol}\) of sodium bicarbonate in \(250.0\textrm{ mL}\) of solution.

Answer

\(0.250\textrm{M}\)

9. Calculate the mass in grams of the solute in each of the following solutions:
1. \(750.0\textrm{ mL}\) of a \(1.50\textrm{M}\) \(\ce{NaOH}\) solution (\(M(\ce{NaOH})=39.997\textrm{ g mol}^{-1}\))

Answer

\(45.0\textrm{ g}\)

1. \(0.200\textrm{ L}\) of a \(150.0\textrm{mM}\) \(\ce{NaCl}\) solution (\(M(\ce{NaCl})=58.44\textrm{ g mol}^{-1}\)).

Answer

\(1.75\textrm{ g}\)

10. Calculate the volume (in litres) of \(0.200\textrm{M}\) solution that can be prepared from \(48.00\textrm{ g}\) of each of the following solutes:
1. \(\ce{KCl}\), \(M=74.551\textrm{ g mol}^{-1}\)

Answer

\(3.22\textrm{ L}\)

2. \(\ce{NaNO3}\), \(M=84.99\textrm{ g mol}^{-1}\).

Answer

\(2.82\textrm{ L}\)

11. Calculate the molar concentration of a \(5.0\%(m/v)\) \(\ce{KOH}\) solution (\(M=56.1056\textrm{ g mol}^{-1}\).

12. Calculate the volume (in millilitres) of water that should be added to a \(3.00\textrm{M}\) stock solution of \(\ce{HCl}\) to make \(100.0\textrm{ mL}\) of \(1.00\textrm{M}\) \(\ce{HCl}\) solution?

13. A dilute \(\ce{NaOH}\) solution was prepared by adding \(100.0\textrm{ mL}\) of water to \(400.0\textrm{ mL}\) of \(0.1\textrm{M}\) stock solution. Determine the molar concentration of the diluted \(\ce{NaOH}\) solution.

14. Calculate the final volume of an \(\ce{H2SO4}\) solution prepared from \(100.0\textrm{ mL}\) of \(0.5000\textrm{M}\) \(\ce{H2SO4}\) if the final concentration is \(0.1500\textrm{M}\).

15. Water is added to \(50.0\textrm{ mL}\) of \(\ce{NaOH}\) stock solution with a concentration of \(10.0\%(m/v)\) to make a final volume of \(250.0\textrm{ mL}\). Determine the final concentration of the solution in \(\%(m/v)\).