NAME 2. A solution is prepared by dissolving 20.18 g of solid K,SO, in eno of ex

Question

NAME 2. A solution is prepared by dissolving 20.18 g of solid K,SO, in eno of exactly 800 ml NAME: 2. A solution is prepared by dissolving 20.18 g of solid K,SO, in enough water to give a volumse of exactly 800 ml. (a). What is the molarity of K,so, in this solution? (6 ) icnol kSo (8 pts) (b). Now suppose that exactly 200 mL of 1.234 M KCI is added to the 800 mL solution from above. Assuming this gives a volume of 1.00 L, what is the concentration of K' ions in the resulting solution? (Both K,so, and KCl act as strong electrolytes when dissolved in water.)

Explanation / Answer

Solution :-

Moles of K2SO4 from the 800 ml solution are calculated as

Moles of K2SO4 = molarity * volume in liter      

                            = 0.145 mol per L * 0.800 L

                            = 0.116 mol K2SO4

So moles of K+ = 0.116 mol K2SO4 * 2 mol K+ / 1 mol K2SO4 = 0.232 mol K+

Now lets calculate the KCl from the 200 ml of the 1.234 M KCl

Moles of KCl = 1.234 mol per L * 0.200 L

                    = 0.2468 mol KCl

Therefore moles of K+ = 0.2468 mol

Now lets find the total moles of the K+

Total moles of K+ = (0.232 mol K+ ) + (0.2468 mol K+) = 0.4788 mol K+

Now lets calculate the molarity of the K+ in the 1.00 L solution

Molarity =moles / liter

               = 0.4788 mol / 1.00 L

               = 0.4788 M K+

So the concnetration of the K+ = 0.4788 M

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