Please explain all answers 1) A solution was prepared by dissolving 6.45 g potas

Question

Please explain all answers

1)

A solution was prepared by dissolving 6.45 g potassium chloride in 86.77 g water. What is the concentration in weight percent for this saline solution?

2) A solution was prepared by adding 1.5283 g of potassium hydroxide to a 100 mL volumetric flask. What is the concentration of potassium hydroxide in moles per liter?

3)Using a pipet, 10 mL of a 0.6505 M acetic acid solution was placed in a 50 mL volumetric flask and the flask filled to the mark with water. What is the concentration of the new, diluted solution?

Explanation / Answer

1)

% ww = mass of solute / mass of solution *100

note that mass of solution = mass of solvet + mass of solute (i.e. water and potassium salt)

% ww = 6.45 / (6.45+86.77) * 100 = 6.9191%

2)

m = 1.5283 g of KOH

V = 100 ml = 0.1 L

M= mol /L

find moles

mol = mass/MW = 1.5283/56.1056 =0.02723 mol

then

M= mol /L = 0.02723 /0.1 = 0.02723 M

3)

V1 = 10 ml of M1 = 0.06505

V 2= 50 ml

apply dilutoin law

M1*V1 = M2*V2

M2 = M1*(V1/V2) = 10/50*0.6505 = 0.1301M

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