Question

You have 100. mL of aqueous 0.40 M CuSO₄ mixed with 100. mL of aqueous 0.20 M Na₂S.

1. What kind of reaction could potentially take place? (a) Bronsted-Lowry acid base (b) redox (c) precipitation (d) no reaction

2. Which of the following is/are the spectator ions in this reaction? (a) SO₄^2-   (b) Na⁺ (c) S^2- (d) Cu²⁺

3. After the solutions are mixed, what will be the concentration of Na⁺ ? (a) 0.10M (b) 0.80M (c) 0.20M (d) 0.40M (e) something else

4. After the solutions are mixed, what will be the concentration of  SO₄^2- ? (a) 0.40M (b) 0.20M (c) 0.80M (d) 0.10

5. Which reactant will limit the amount of product that can form? (a) Cu²⁺ (b) S^2- (c) something else

6. This mixture will establish equilibrium in mere fractions of a second. After it does, what will be the concentration of Cu²⁺? (a) something much smaller than 0.10M (b)0.40 M (c)0.10 M (d) 0.20M (e)zero M

7. This mixture will establish equilibrium in mere fractions of a second. After it does, what will be the concentration of S^2-?

Answers and explanations to any of the questions above would be very helpful.

Answer 1

You have 100. mL of aqueous 0.40 M CuSO4 mixed with 100. mL of aqueous 0.20 M Na2S.

1. What kind of reaction could potentially take place?

ions present:

Cu2+; SO4-2; Na+ + S-2

note that cu2+ and S-2 are not souble they form CuS

(a) Bronsted-Lowry acid base (b) redox (c) precipitation (d) no reaction

2. Which of the following is/are the spectator ions in this reaction? (a) SO42-   (b) Na+   (c) S2-   (d) Cu2+

spectator ions --> must not react , they remain in solution, so

SO4-2 and Na+ are not reacting, those are spectator ions

(a) SO42-   (b) Na+   (c) S2-   (d) Cu2+

3. After the solutions are mixed, what will be the concentration of Na+ ?

Vtotal = 100+100 = 200 mL

[Na+] = 0.2*2 = 0.4 M initially after 50% dilution -_> 0.2 M

(a) 0.10M (b) 0.80M (c) 0.20M (d) 0.40M (e) something else

4. After the solutions are mixed, what will be the concentration of  SO42- ?

SO4-2 iniailly --> 0.40

when halved --> 0.20 M

(a) 0.40M (b) 0.20M (c) 0.80M (d) 0.10

5. Which reactant will limit the amount of product that can form?

the limiting reactant --> Na2S, since 0.2 M and th eother species is 04 M

(a) Cu2+  (b) S2-  (c) something else