Effect of changing concentration

Question 1

Mn2+ (aq) + H2S (aq) ⇋ MnS (s) + 2H+ (aq)
What effect does the addition of more H2S have on the position of the equilibrium?

Answer 1

Increasing the concentration of H2S will shift the equilibrium to the right hand
side
This will increase the yield of MnS and H

Question 2

Mn2+ (aq) + H2S (aq) ⇋ MnS (s) + 2H+ (aq)
What effect does the addition of acid (H+) into the mixture have on the position of equilibrium?

Answer 2

Increasing the concentration of H+ will shift the equilibrium to the left hand
side
This will decrease the yield of products

Question 3

If there are less products, what happens to the yield?

Answer 3

Less yield

Question 4

If there are more products, what happens to the yield?

Answer 4

More yield

Question 5

Write the equation for the chromate-dichromate equilibrium

Answer 5

2 CrO4 2-(aq) (yellow) + 2 H+ (aq) ⇋ Cr2O7
2-(aq) (orange) + H2O (l)

Question 6

2 CrO4 2-(aq) (yellow) + 2 H+ (aq) ⇋ Cr2O7
2-(aq) (orange) + H2O (l)
State and explain the observations seen when HCl is added to the above mixture at equilibrium

Answer 6

Equilibrium shifts to the right in order to reduce the concentration of H+ ions
The yield of products increases
The colour would become more orange

Question 7

2 CrO4 2-(aq) (yellow) + 2 H+ (aq) ⇋ Cr2O7
2-(aq) (orange) + H2O (l)
State and explain the observations seen when NaOH is added to the above mixture at equilibrium

Answer 7

Adding OH- removes H+
Equilibrium shifts to the left in order to increase the concentration of H+ ions
The yield of products decreases
The colour would become more yellow

Question 8

Write the equation for the hydrogen carbonate- carbon dioxide equilibrium

Answer 8

H+ + HCO3- ⇋ H2CO
H2CO3 ⇋ H2O +CO2

Question 9

What is the importance of the hydrogen carbonate- carbon dioxide equilibrium?

Answer 9

Controlling the pH of blood

Question 10

State and explain what will happen when acid is added to a hydrogen
carbonate solution?

Answer 10

More H2CO3 produced as equilibrium of the 1st equation shifts to the right (to reduce the H+ ion concentration)
Equilibrium of 2nd equation shifts to the right in order to remove the extra H2CO3 produced
Yield of H2O and CO2 increases
You would see bubbles of CO2