2. Chemistry 20

3.  concentration: a ratio that compares the quantity of solute to the quantity of solution  A dilute solution has a relatively small quantity of solute per unit volume of solution compared to a concentrated solution.

4.  A solution in which a pure liquid is dissolved in water may have a percentage volume by volume (% V/V) reported.  Ex. Vinegar is labeled 5% V/V acetic acid

5.  What is the concentration (in % V/V) of a solution in which 225 mL of pure sulfuric acid is found in 2.00 L of solution?

7.  An ammonia solution in a beaker is labeled 13.0 % V/V. What volume of pure ammonia has been dissolved in making 350 mL of this solution?

9.  Another common concentration ratio used for consumer products is “percentage weight by volume” or % W/V  Ex. Hydrogen peroxide is labeled 3% W/V

10.  What is the concentration (in % W/V) of a solution in which 74.0 g of sugar is found in 1500 mL of solution?

12.  A sodium chloride solution in a beaker is labeled 3.5 % W/V. Calculate the volume of this solution that contains 750 mg of dissolved solute.

14.  A third concentration unit is the “percentage weight by weight”, or % W/W.  Ex. A stainless steel alloy contains 11.5% W/W chromium.

15.  A sterling silver ring has a mass of 12.0 g and contains 11.1 g of pure silver. What is the concentration (in % W/W) of silver in the ring?

17.  A bronze medal is 88% W/W copper and 12% W/W tin. What mass of each metal is present (to the tenth) in a 282 g bronze medal?

19.  In solutions found in the environment (ex. iron in well water), we often find very low concentrations.  Very small concentrations are often expressed in parts per million (ppm) or even parts per billion (ppb).

20.  At these very low concentrations, the solution is extremely dilute. Dilute aqueous solutions are assumed to have the same density as pure water (exactly 1 g/mL).

21.  Well water is not recommended for drinking if dissolved lead has a concentration of 15 ppb or higher. What is the maximum mass of lead that can be dissolved in 20.0 L of water that is safe to drink?

23.  A sample of hard water contains 300 ppm calcium carbonate. What mass of calcium carbonate will be found in 500 mL of hard water?

24.  m = 0.150 g

25.  A mountain spring water source is analyzed to contain 485 ppb of dissolved iron. What volume of spring water must be collected in order to contain 1.00 g of dissolved iron?

27.  Concentration Practice Problems  Solubility Graphing Assignment due tomorrow!