Concentration and Dilution Practice Questions PDF

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Here is some concentration and dilution chemistry practice questions with solutions....

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Concentration and Dilution - Practice Questions Answer the following questions using GRASS format: 1. The food industry uses calcium chloride, CaCl2, to make processed foods, such as pickles, taste saltier without adding sodium chloride. What is the amount concentration of a 750 mL sample of a calcium chloride solution that contains 1.5 mol of calcium chloride? [ans: 2.0 mol/L] C = n/V C = 1.5/0.750 C = 2.0mol/L Therefore, the concentration of a 750ml sample of calcium chloride solution that contains 1.5mol of calcium chloride is 2mol/L.

2. Phosphoric acid, H3PO4, is the active ingredient in many consumer products designed to remove rust. What is the amount concentration of a solution that contains 63 g of phosphoric acid in 250 mL? [ans: 2.6 mol/L] n= m/M

M= (3x1.008) + (4x15.999) + (30.97) M= 98g/mol

n=63/98 n= 0.64mol C= n/V C= 0.64/0.250 C= 2.52mol/L Therefore, the concentration of a solution that contains 63g of phosphoric acid in 250 mL, is 2.52mol/L

3. Fructose, C6H12O6, is a natural sugar in apple juice. A person with diabetes must be aware of the quantity of sugar she consumes. The concentration of fructose in a certain brand of apple

juice is 0.67 mol/L. What mass of fructose is present in a 250 mL bottle of apple juice? [ans: 30 g] n= CV n= 0.67(0.250) n= 0.17mol m= nM M= (12.01x6) + (6x16) + (1.008x12) M= 180.156g/mol m= 0.17(180.156) m= 30.63g Therefore the mass of the fructose present in the apple juice is 30.63g.

4. Soap makers use a 6.0 mol/L solution of sodium hydroxide, NaOH, to make soap. What volume of solution can be prepared using 125 g of sodium hydroxide? [ans: 520 mL] n= m/M M= 16+ 1.008+ 22.99 M= 40g/mol n= 125/40 n= 3.125mol C= n/V 1/C= V/n V= n/C V= 3.125/6 V= 0.520 Therefore the volume is 0.52L

1. What is the final concentration when 4.5 L of 3.0 mol/L car battery acid is diluted to 20.0 L? [ans: 0.68 mol/L] CV=CV 3(4.5)= 20C

C= (3(4.5))/20 C= 0.675 The concentration is 0.68mol/L

2. What volume of a 6.0 mol/L sodium hydroxide solution is required to produce 850 mL of a 0.100 mol/L solution? [ans: 14 mL] CV=CV 6V= 0.1(0.85) V= (0.1(0.85))/6 V= 0.014 The required amount is 14mL.

3. A teacher needs to prepare 4.5 L of 1.0 mol/L ethanoic acid (acetic acid) for an investigation. What volume of concentrated 17.4 mol/L ethanoic acid is required? [ans: 0.26 L or 260 mL] 14.4V= 4.5 V= 4.5/17.4 V= 0.26 The required amount is 0.26L

4. 250 mL of a 0.100 mol/L iron(III) nitrate solution is prepared using 75 mL of a stock solution. What is the amount concentration of the stock solution? [ans: 0.33 mol/L] 0.075C= 0.1(0.25) C= (0.1(0.25))/0.075 C=0.33 The concentration of the stock solution is 0.33mol/L....