Question

# You have 47.0 mL of a 0.500 M stock solution that must be diluted to 0.100...

You have 47.0 mL of a 0.500 M stock solution that must be diluted to 0.100 m. Assuming the volumes are additive, How much water should you add?

(a) 1.How many grams of CaCl2 are needed to make 866.0 g of a solution that is 39.0% (m/m) calcium chloride in water? Note that mass is not technically the same thing as weight, but (m/m) has the same meaning as (w/w).

(a)2. How many grams of water are needed to make this solution?

(b) What is the volume percent (v/v) of an alcohol solution made by dissolving 135 mL of isopropyl alcohol in 747 mL of water?

(c) The mass of solute per 100 mL of solution is abbreviated as % (m/v). How many grams of sucrose are needed to make 735 mL of a 30.0% (w/v) sucrose solution?

You have 47.0 mL of a 0.500 M stock solution that must be diluted to 0.100 m. How much water should you add

Ans:

$MV = M'V' \\ \: \text { 0.500 M} \times \text { 47.0 mL} = \text { 0.100 M} \times V' \\ \: \text { 235 mL}$

Amount of water to be added $= \text { 235 mL} - \text { 47.0 mL} = \text { 188 mL}$

(a) 1.How many grams of CaCl2 are needed to make 866.0 g of a solution that is 39.0% (m/m) calcium chloride in water?

Ans: Let w g of CaCl2 are needed.

$\text { Weight percent} = \dfrac { \text { mass of CaCl2} }{ \text { mass of solution} } \times 100 \\ \: \text { 39} = \dfrac { \text { w}} { \text { 866} } \times 100 \\ \: \text { w} = \text {338 g }$

(a)2. How many grams of water are needed to make this solution?

Ans: $\text { 866 g} - \text { 338 g} = \text { 528 g}$ of water are needed to make this solution.

(b) What is the volume percent (v/v) of an alcohol solution made by dissolving 135 mL of isopropyl alcohol in 747 mL of water?

Ans:

$\text {Volume percent}=\dfrac { \text {volume of isopropyl alcohol}} { \text {volume of isopropyl alcohol } +\text {solution volume} } \times 100$

$\text { Volume percent} = \dfrac { \text { 135 mL } } { \text {135 mL } +\text {747 mL } } \times 100 = \text { 15.3}$ %

(c) The mass of solute per 100 mL of solution is abbreviated as % (m/v). How many grams of sucrose are needed to make 735 mL of a 30.0% (w/v) sucrose solution?

Ans: $\text {w/v percent}=\dfrac { \text { Mass of sucrose}} { \text {solution volume} } \times 100$

$\text {30.0}=\dfrac { \text { Mass of sucrose}} { \text {735 mL} } \times 100$

$\text { Mass of sucrose} = \text {221 g }$

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