1 INTRODUCTION TO CONCENTRATION Practice Problems You must know the differences among the following terms to be successful making solutions. Solution: A solution is a homogeneous mixture in which one or more substances (the solute(s) are dissolved in another substance (the solvent)). Concentration: the amount of a solute in a particular volume or mass of the solution. Amount: how much of a component is present Problem 1: Which of the following are concentrations? a. 5 g/L b. 17 grams c. 84 moles/L d. 22.2 ng/mL e. 4 g f. 0.005 units/L g. 14 mmoles Problem 2: Describe how to prepare 100 mL of 3 grams / mL KCl (The procedure to prepare this solution is very straightforward and requires no real knowledge of chemistry! You may solve this problem using either proportions or unit cancellation.) Problem 3: Which of the following solutions is the most concentrated? 30 mg/L 30 g/L Problem 4: How much solute is present in 225 mL of a 50 mg/mL solution of NaCl?