Equilibrium
What happens if the volume of a gas-phase reactant at equilibrium decreases?
The equilibrium shifts towards the side with fewer gas molecules.
All gases escape from the system, so there is no longer an equilibrium.
Nothing, the volume change has no effect on equilibrium positions.
The equilibrium shifts towards the side with more gas molecules.
In an industrial synthesis reactor where hydrogen gas (H₂) and iodine gas (I₂) are at equilibrium forming hydrogen iodide (2HI), how would an increase in pressure affect the system?
It would favor decomposition of hydrogen iodide into hydrogen and iodine gases.
It would shift towards producing more hydrogen iodide due to fewer moles of gas on that side of the equation.
Increased pressure has no effect since all components are gases with similar molar volumes.
It would result in decreased production of hydrogen iodide because it has higher molar mass than reactants.
How does adding a catalyst to a reversible reaction affect its state of equilibrium?
Causes an immediate shift towards the products.
No effect on the state of equilibrium.
Decreases the equilibrium constant value.
Increases the equilibrium constant value.
If a chemical system at equilibrium is disturbed by adding more product, what does Le Châtelier's principle predict will happen?
The equilibrium shifts toward reactants.
No shift in equilibrium occurs because it's already at balance.
Equilibrium constants become smaller.
The system consumes energy from surroundings faster.
Which expression represents the reaction quotient, Q, for a generic reaction aA + bB ⇌ cC + dD?
What happens when NH4Cl(s) is added into a sealed flask containing NH3(g) and HCl(g) at chemical equilibrium?
The position of equilibrium does not change since solid addition doesn't alter gaseous concentrations.
Equilibrium moves towards decomposition producing more gaseous species that counteract increasing total pressure.
It leads directly to production of more solids lowering vapor pressure above solution.
Equilibrium shifts towards NH4Cl formation reducing both NH3(g) and HCl(g).
What impact would decreasing volume have on an equilibrated mixture with this reaction under gaseous conditions CO(g) + Cl_₂(g) ⇌ COCl_₂(g)?
Shifts left, reducing production of COCl_2.
No change no matter of pressure.
Shifts right, favoring production of COCl_2.

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If a chemical system at equilibrium is subjected to an increase in concentration of products, what is likely to happen according to Le Châtelier’s Principle?
The system will shift toward reactants.
The system will remain at equilibrium without any shift.
The system will produce even more products.
The volume of the container will increase automatically.
What does the reaction quotient (Q) indicate when it is equal to the equilibrium constant (K)?
The reaction will not proceed.
The reactants are favored.
The products are favored.
The system is at equilibrium.
Consider the equation 2CH₄ (g) ⇌ C₂H₂ (g)+ 3H₂ (g). The given K constant is 0.25. If the reaction begins with 4M CH₄, 5M C₂H₂, and 2M H₂, what is Q?
Q = 2.5, so the reaction shifts right.
Q = 0.25, so the system is already at equilibrium.
Q = 2.5, so the reaction shifts left.
Q = 250, so the reaction shifts right.