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Calculate the final concentration of each of the following diluted solutions. A)

ID: 229714 • Letter: C

Question

Calculate the final concentration of each of the following diluted solutions.

A) 4.0 L of a 4.0 M HNO3 solution is added to water so that the final volume is 8.0 L .

Express your answer using two significant figures.

B) Water is added to 0.45 L of a 6.0 M KOH solution to make 2.0 L of a diluted KOH solution.

Express your answer using two significant figures

C) A 80.0 mL sample of 8.0 % (m/v) NaOH is diluted with water so that the final volume is 200.0 mL.

Express your answer using two significant figures.

D) A 8.0 mL sample of 50.0 % (m/v) acetic acid (HC2H3O2) solution is added to water to give a final volume of 25 mL .

Express your answer using two significant figures.

Explanation / Answer

A.      Initial                               Final

     M1= 4.0M                          M2=

    V1= 4.0L                            V2= 8.0L

for dilution        M1V1 = M2V2

                       M2= 4.0x4.0/8.0 = 2.0M

final concentration of HNO3 = 2.0M

B)         Initial                              Final

        M1= 6.0M                         M2=

       V1= 0.45L                          V2= 2.0L

              M1V1= M2V2

              M2= 6.0x0.45/2.0 = 1.35M

final concentration of KOH= 1.35M = 1.4M

C) 8.0%(m/v) NaOH solution means 8.0 grams of NaOH is dissolved in 100 ml of solution.

mass of NaOH= 8.0 grams

molar mass of NaOH= 40 gram/mol

volume = 100 ml

Molarity = mass/molar mass x1000/v in ml

Molarity = 8.0/40 x1000/100 = 2.0M

Initial concentration of NaOH= 2.0M

initial volume of NaOH= 80.0ml

final volume= 200.0ml

final concentration of NaOH= 2.0x80.0/200.0 = 0.8M

final concentration of NaOH= 0.80M

D 50.0%(m/V) acetic acid means 50.0 grams of acetic acid is present in 100 ml of solution

mass of acetic acid = 50.0 grams

molar mass of acetic acid= 60 gram/mole

volume= 100 ml

M= 50.0/60 x1000/100= 8.33M

inital concentration of   acetic acid= 8.33M

initial volume= 8.0ml

final volume=25ml

final concentration of acetic acid= 8.33x8.0/25 = 2.666 M

final concentration of acetic acid = 2.7M

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