Given the two reactions H2S(aq)⇌HS−(aq)+H+(aq), K1 = 9.76×10−8, and HS−(aq)⇌S2−(aq)+H+(aq), K2 = 1.22×10−19, what is the equilibrium constant Kfinal for the following reaction?

Kf  = 8.4 x 10²⁶

Explanation:

H₂S(aq) ⇌ HS⁻(aq) + H⁺(aq)

K1 = [HS⁻] [H⁺] / [H₂S]

K1 = 9.76×10−8

9.76×10−8 =  [HS⁻] [H⁺] / [H₂S]

HS⁻(aq) ⇌ S²⁻(aq) + H⁺(aq)

K2 = 1.22×10−19

K2 = [S²⁻] [H⁺] / [HS⁻]

S²⁻ (aq)  + 2H⁺(aq)  ⇌ H₂S(aq)

Kf = [H₂S] /[S²⁻] [H⁺]²

To obtain the value of Kf, the relationship between Kf, k1 and k2 have to be determined;

K1K2 = ( [HS⁻] [H⁺] / [H₂S]) * [S²⁻] [H⁺] / [HS⁻]

K1K2 = [H⁺]² [S²⁻] / [H₂S]

K1K2 = 1 / Kf

Kf = 1  / (K1K2)

Kf = 1 / (9.76×10⁻⁸ * 1.22×10⁻¹⁹)

Kf = 1 / (11.91 x 10-27)

Kf = 0.084 x 10²⁸

Kf  = 8.4 x 10²⁶

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

for step 7 table c on the lab "newtons law of action"   the average time it took the car to travel .25 meters   was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )