Activity 22- Zero Emission Vehicles Introduction Air pollution and air quality a

Question

Activity 22- Zero Emission Vehicles Introduction Air pollution and air quality are major issues in the Central Valley. Zero emission vehicles, such as those using hydrogen fuel cells, have been discussed as possible avenues to reduce harmful emissions. Many of these vehicles have drawn criticism due to the energy, and therefore emissions, needed to make the fuels. In this activity we will look at the generation of hydrogen gas from ammonia, a significantly less endothermic process than its production from water. Instructions Write a balanced chemical equation for the decomposition of ammonia gas in the presence of a ruthenium catalyst to form nitrogen gas and hydrogen gas 1. Write expressions for the reaction quotient, equilibrium constant (Kc), and equilibrium constant (%) for this reaction 2. For each of the following sets of conditions calculate the reaction quotient. Use this value to predict how this reaction will shift with time. Will it shift to form more products, more reactants, or stay the same? For this reaction Kc = 17 3. Predicted Shift Set NHl 0.100.041 M OM OM 0.041 M 0.0012 M 0.041 M 0 M C 0.030 M 0.030 M0.030 M D 4.08*10 M 0.041 M 0.041 M E 3.2 10 M 0.16 M 0.0054 M More questions on the next page! Fresnn State Chemietrv 4. Answer the following follow-up questions: For a reaction to move towards reactants, what must be true of the rates of the forward and reverse reactions? b. For a reaction to move towards products, what must be true of the rates of the forward and reverse reactions? c. For a reaction at equilibrium, what must be true of the rates of the forward and reverse reactions d.

Explanation / Answer

Q1

NH3(g) = N2(g) + H2(g)

balance

2NH3(g) <-> N2(g) + 3H2(g)

Q2

expression for Kc

First, let us define the equilibrium constant for any species:

The equilibrium constant will relate product and reactants distribution. It is similar to a ratio

The equilibrium is given by

rReactants -> pProducts

Keq = [products]^p / [reactants]^r

For a specific case:

aA + bB = cC + dD

Keq = [C]^c * [D]^d / ([A]^a * [B]^b)

Kc = [N2][H2]^3 /( [NH3]^2)

and Kp

Kp = (P-N2)(P-H2)^3 / (P-NH3)^2

Q3.

if Kc = 17, the Kc = [N2][H2]^3 /( [NH3]^2)

A)

Not in equilibrium since [H2] is zero

shift goes towards H2 production (right)

b)

not in equilbirium

shift goes towards NH3 production

c)

Q = (0.03)(0.03^3)/(0.03^2) = 0.009

Q < K, then expect shift towards products

d)

Q = (0.041*0.041^3)/(4.08*10^-4)^2

Q = 16.97520

Q = K, approx

this is in equilbirium

e)

Q = (0.16 * 0.0054^3)/(3.2*10^-6)^2

Q = 2460.375

Q > K

expect shift to the left

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