Question

# Indicate the concentration of each ion present in the solution formed by mixing the the following....

Indicate the concentration of each ion present in the solution formed by mixing the the following.
44.0 mL of 0.100 M Na2SO4 and 25.0 mL of .200 M KCl. Assume that the volumes are additive.
Use three significant figures for all answers.

Molarity of Na2SO4 (M1)= 0.100M = 0.100 mol/L

Volume of Na2SO4 (V1)= 44.0 mL

Volume of KCl added = 25 mL

Molarity of KCl = 0.200 M

Total volume of solution(V2) = 44 + 25 = 69.0 mL

Let molarity of Na2SO4 after mixing be M2

From molarity equation we have

M1V1 =M2V2

0.100M*44 mL = M2 * 69 mL

M2 = 0.0638 M

Na2SO4 dissociates as :

Na2SO4 2Na+ + SO42-

Thus, [Na+] = 2*[ Na2SO4 ] = 2* 0.0638M = 0.128M

[SO42-] =[ Na2SO4 ] = 0.0638M

Similarly KCl concentration is

0.200M * 25 mL = M2 * 69 mL

M2 = 0.0725 M

KCl dissociates as:

KCl K+ + Cl-

[KCl] = [K+ ] = [Cl-] = 0.0725 M

Hence, [Na+] =  0.128M ; [SO42-] = 0.0638M ; [Cl-] = 0.0725 M ; [K+ ] = 0.0725 M

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