Reaction Yield

Lesson 6

The Yield of a Reaction

High yield

The yield is the amount of products.

reactants products⇌

Low yield

reactants products⇌

The Haber Process is used to make ammonia

N2(g) + 3H2(g) ⇌ 2NH3(g) + energy

4 2

To ensure a high yield

low temperature

high pressure

remove NH3

add N2 and H2

The Haber Process is used to make ammonia

N2(g) + 3H2(g) ⇌ 2NH3(g) + energy

4 2

To ensure a high rate

high temperature- 600 0C

high pressure- 20000 Kpa

add N2 and H2

add catalysts Os and Ur

1 2

N2O4(g) ⇋ 2NO2(g) + 59 KJ

Increasing the yield

low temperature

low pressure

add N2O4

remove NO2

1 2

N2O4(g) ⇋ 2NO2(g) + 59 KJ

Increasing the rate

high temperature

high pressure

add N2O4

add a catalyst

Yield is the amount of product relative to reactants at equilibrium.

Know the difference between Rate and Yield!

Rate is how fast you get to equilibrium.

1. What conditions will produce the greatest yield?

P2O4(g) ⇋ 2PO2(g) ∆H = -28 kJ

A. high temperature & high pressure

C. high temperature & low pressureD. low temperature & high pressure

+ 28KJ

B. low temperature & low pressure

2. What conditions will produce the greatest rate?

Zn(s) + 2HCl(aq) → H2(g) + ZnCl2(aq)

A. high Zn surface area, low [HCl], low temperatureB. low Zn surface area, high [HCl], high temperature

D. high Zn surface area, high [HCl], low temperature

C. high Zn surface area, high [HCl], high temperature

3. What increases the rate?

Zn(s) + 2HCl(aq) → H2(g) + ZnCl2(aq)

 A. removing H2

B. removing ZnCl2(aq)

C. lowering pressureD. adding HCl

Graphing Equilibrium N2O4(g) ⇋ 2NO2(g) + 59 KJ

1. Adding N2O4

     

[N2O4]

[NO2] 2x

x

Graphing Equilibrium 

N2O4(g) ⇋ 2NO2(g) + 59 KJ

2. Removing NO2

     

[N2O4]

[NO2]

2x

x

Graphing Equilibrium N2O4(g) ⇋ 2NO2(g) + 59 KJ

3. Increase Temperature

     

[N2O4]

[NO2] 2x

x

Graphing Equilibrium N2O4(g) ⇋ 2NO2(g) + 59 KJ

[N2O4]

[NO2]

2x

x

3. Decrease Volume- all concentrations + pressure goes up!