Chemistry 162
Q=K
The system is at equilibrium and no further net charge occurs
Which of the following changes will cause the equilibrium shown to shift toward the products? Fe3O4 (s) + 4H2 (g) = 3Fe (s) + 4H20 (g)
- Add H2 (g) without changing the volume - Remove H2O (g) from the reaction vessel
Which of the following will change the pressure in a reaction involving only gases at equilibrium? Select all that apply.
- Adding an inert gas - Changing the volume of the container - Adding or removing a reactant or product
1.9 moles of HI are added to an evacuated, sealed 10.-L reaction vessel and allowed to decompose according to the following reaction: H2 (g) + I2 (g) = 2 HI (g); Kc = 1.26 x 10^-3. Which of the following options correctly reflect how to calculate [H2] at equilibrium ? Select all that apply.
- If the change in [H2] = +x, then at equilibrium [I2] = x. - The initial [HI] = 0.19 M - Kc = 1.26 x 10^-3 = (0.19-2x)^2/x^2
Which of the following statements correctly describe how an equilibrium system containing gases will respond to changes in volume and/or pressure, if the temperature remains unchanged? Select all that apply.
- If the volume is decreased the reaction shifts in the direction that produces fewer moles of gas - If the total number of moles of gas in the products and reactants is the same, a change in volume will not affect the equilibrium position - If an inert gas is added there will be no affect on the equilibrium position
If O2 (g) is added to the equilibrium system 2NO (g) = N2 (g) + O2 (g), which of the following will be observed? Select all that apply.
- The concentration of NO will increase - The reaction will shift to the left
The Haber process is used to produce ammonia in industy. How does this process utilize Le Chatelier's principle to maximize reaction yields?
- The reaction is carried out at high pressures - Product is removed by condensation, so that the equilibrium continually shifts to the right to generate more product
Which of the following statements correctly describe how a system at equilibrium will respond to a change in concentration of any species that appears in the expressions for Q and K?
-The value of Kc is not affected by changes in concentration -If a reactant is removed from the system the equilibrium will shift towards the reactants -If a reacting substance is added the equilibrium position will shift to use up the substance
Calculate the equilibrium concentration of PCl3 for the equilibrium system represented below. PCl5 (g) = PCl3 (g) + Cl2 (g); Kc = 62; [PCl5] = 0.00582 M and [Cl2] = 0.731 M.
0.49 M
0.20 mol of N2 (g) and 0.15 mol of 02 (g) are placed in a 1-L container and allowed to react according to the equation N2 (g) + O2 = 2NO (g); Kc = 4.10 x 10^-4. Place the following steps to solve for [NO] at equilibrium in the correct order, starting with the first step.
1. Assume that the change in [N2] = x 2. Kc = 4.10 x 10^-4 = (2x)^2/(0.20-x)(0.15-x) 3. Assume that x is small so that 4.10 x 10^-4 = 4x^2/0.20 x 0.15 4. Solve for x, then [NO]eqm=2x 5. Check that x<5% of both 0.20 and 0.15
A reaction is started with 2.8 M H2 (g) and 1.6 M I2 (g). Fill in the reaction table below correctly in order to calculate the value of Kc for the reaction H2 (g) + I2 (g) = 2HI (g).
A) 2x B) 2.8-x C) 1.6-x D) 2x
If an equilibrium system contains gaseous reactants and/or products, a change in volume will cause a change in concentration and pressure. A decrease in volume will cause the system to shift in the direction that produces (__A__) moles of gas in total, whereas an increase in volume causes a shift in the direction that produces (__B__) moles of gas in total.
A) Fewer B) More
If a reaction has a relatively (__A__) value of K and fairly (__B__) initial concentrations, equilibrium calculations can be simplified by assuming that the change in concentration (x) is (__C__) compared to [reactant]init. The assumption is justified as long as x is less than (__D__)% of the initial concentration.
A) Low B) High C) Small D) 5
Q<K
The reaction proceeds toward the products
increase volume results in
a decrease in pressure
Which of the following options correctly describe how a system at equilibrium will respond to a change in temperature? Select all that apply.
- A change in temperature will cause a change in Kc - If the forward reaction is exothermic, an increase in temperature causes a shift to the left
SO2 (g) + Cl2 (g) = SO2Cl2 (g) Add 1 mol of Ne (g) will
Not affect the equilibrium
adding a solid results in
no effect on pressure
If a system at equilibrium is disturbed by changing the concentration of a reactant or product, the equilibrium (__A__) will shift but the ratio of product to reactant will be (__B__) once the system reestablishes equilibrium. The value of K will be (__C__).
A) Position B) The same C) Unchanged
Le Chatelier's principle states that when a chemical system at equilibrium is disturbed, the system will undergo a net reaction that (___A___) the effect of the disturbance and will attain a new (___B___) position.
A) Reduces B) Equilibrium
A decrease in temperature causes
K to increase if deltaH(null) < 0
An increase in temperature causes
K to increase if deltaH(null) > 0
SO2 (g) + Cl2 (g) = SO2Cl2 (g) Double the partial pressures of all species will
Shift equilibrium towards the products
SO2 (g) + Cl2 (g) = SO2Cl2 (g) Increase the volume of the container will
Shift equilibrium towards the reactants
In a given experiment, 0.10 atm of each component in the following reaction is placed in a sealed container. In which direction will the reaction proceed? 2NOBr (g) = 2NO (g) + Br2 (g) where Kp = 60.6 at 100 degC
The reaction proceeds toward the products
Q>K
The reaction proceeds toward the reactants
If the concentration of a reactant or product is changed in a system at equilibrium, what will happen to the value of K if the temperature remains constant?
The value of K will remain unchanged because the ratio of product to reactant concentration does not change
adding a gaseous reactant results in
an increase in pressure
adding an inert gas results in
an increase in total pressure, but no change in partial pressures of gases
If deltaH(null) > 0, will decrease
when temperature decreases
If deltaH(null) < 0, will decrease
when temperature increases
