CHEMISTRY 2 CHAPTER 14 Answers

what is the effect of change of volume on a chemical reaction that includes gaseous reactants or products initially at equilibrium?

decreasing the volume increases the pressure, which causes the reaction to shift in the direction that has the few number of moles of gas particles. increasing the volume decreases the pressure. which causes the reaction shift in the direction has an equal number of moles of gas on both sides of the chemical equation, then a change in volume produces no effect on the equilibrium.

what is the significance of equilibrium constant? what does a large equilibrium constant tell us about a reaction? a small one?

the equilibrium constant tells you how far the raction has proceeded once the equilibrium is reached. If the equilibrium constant for a reaction is large , the equilibrium point of the reaction lies far to the right and therefore product-favored . the concentration of products are large and the concentration of the reactants are small.

Explain the difference between Kc and Kc? For Given reaction, how are the two the two constants related?

the expression for Kp takes the form of the expression for Kc, except that we use the partial pressure of each gas in place of its concentration. The two constants are related by the equation Kp=Kc(RT) ^∆n when ∆n=c + d - a - b

(c) Q = K

the reaction is at equilibrium and the reaction will not proceed in either direction

what happens to a chemical system at equilibrium when that equilibrium is distributed.

when a chemical system at equilibrium is disturbed , the system shifts in a direction that minimizes the disturbance

What happens to the value of the equilibrium constant for a reaction if the reaction equation is reversed? what happens if it is Multiplied by a constant?

when a reaction equation is reversed then the value of the equilibrium constant is inverted into its reciprocal. If you multiply the Coefficient in the equation by a factor, then the equilibrium constant is raised to the power of the same factor.

what is the effect of a change in the concentration of a reactant or product on a chemical reaction initially at equilibrium

1. Increasing the concentration of one or more of the reactants (Q < K) causes the reaction to shift to the right.

many equilibrium calculations involve finding the equilibrium concentration of reactants and products given their initial concentrations ad the equilibrium constant outline the general procedure used in solving these kinds of problems

1. Using the balanced equation as a guide prepare a table showing the known initial concentrations of the reactants and products.

what is the effect of a change in the concentration of a reactant or product on a chemical reaction initially at equilibrium.

2. Increasing the concentration of one or more of the products (Q>K) causes the reaction to shift to the left

what is the effect of a change in the concentration of a reactant or product on a chemical reaction initially at equilibrium.

3. Decreasing the concentration of one or mor the reactants (Q> K) causes the reaction to shift to the left.

what is the effect of a change in the concentration of a reactant or product on a chemical reaction initially at equilibrium.

4. Decreasing the concentration of one or more of the product (Q<K) causes the reactions to shift to the right.

What is the definition of the reaction quotient (Q) for reaction? what does Q measure

A reaction quotient is the ratio at any point in the reaction of the concentrations of the products of a reaction raised to their stoichiometric coefficients, to the concentrations of the reactants raised to their stoichiometric coefficients. For gases with amounts measured in atmospheres the reaction quotient compares the progress of a reaction to the equilibrium state of the reaction.

what units should be used when expressing concentrations or partial pressures in the equilibrium constant? what are the units of Kp and Kc? Explain

Concentration and partial pressures within the equilibrium constant are expressed in units of Molarity and and atmospheres, respectively, the units of Kc and Kp are not included when expressing the value of the equilibrium constant

What is a dynamic equilibrium? why is it called dynamic?

Dynamic equilibrium for a reaction is the condition in which the rate of rate of the forward reaction equals the rate of the reverse reaction. It is called "dynamic" because the forward and reverse reaction are still occuring.

a small one?

If the equilibrium constant for a reaction is small the equilibrium point of the reaction is small , the equilibrium point of the reactions lies far left and therefore the reactant-favored. The concentrations of products are small and the concentration of the reactants are large.

what is the effect of a temperature change on a chemical reaction initially at equilibrium? how does the effect differ for an exothermic reaction compared to an endothermic one?

If the temperature of a system at equilibrium is changed, the system will shift in a direction to counter that change. in an exothermic reaction, heat is considered a product. increasing the temperature causes an exothermic reaction to shift to the left and the value of the equilibrium constant decreases. Decreasing the temperature causes an exothermic reaction to shift to the right and the value of the equilibrium constant increases. In an endothermic equation, heat is considered a reactant. Increasing the temperature causes and endothermic reaction to shift to the right and the value of the equilibrium constant increases. decreasin the temperatures causes an endothermic reaction to shift to the left and the value of the equilibrium constant decreases

If two reactions sum to an overall reaction, and the equilibrium constants for the two reactions are K1 and K2 what is the equilibrium constant for the overall reaction

If you add two or more individual chemical equation to obtain and overall equation, then multiply the corresponding equillibrium constant other to obtain the overall equilibrium constant. Thus, the Equilibrium constant for this hypothetical reactionis K1 X K2

16. In equilibrium problems involving equilibrium constants that are small relative to the initial concentrations of reactants, we can often assume that the quanity x (which represents how far the reaction proceeds toward products) is small. when this assumption is made the quanity x can be ignored when it is subtracted from a large number, but not when it is multiplied but a large number. In other words, 2.5 - x ~2.5, but 2.5x ≠ 2.5. explain why a small x can be ignored in the first case, but not in the second.

It cannot be ignored in the second case because as x approached 0 the concentration approaches zero.

why are the concentrations of solids and liquids omitted from equilibrium expressions?

The concentration of a solid does not change and depends only on density. So it remains constant as long as some of the solid is present. the same applies to pure liquids. Thus, the concentration of solids and pure liquids are not included in an equilibrium constant expression.

Does the value of the equilibrium constant depend on the initial concentration of the reactants and products? Do the equilibrium concentration of the reactants and products and the equilibrium concentration of only one reactant or product?

The equilibrium constant will always be the same at a given temperature, regardless of the initial concentration. Whether you start with only reactants or only products, the reactions reaches equilibrium concentration in which the equilibrium constant is the same.. No matter what the initial concentrations are, the reaction will always go in a direction so that the equilibrium concentrations give the same K value. for any reaction, the equilibrium concentration of the reactants and products will depend on the initial concentrations. In general, the will vary from one set of initial concentrations to another

what is the value of Q when each reactant and prooduct is in the standard state?

The standard state for a substance in a solution is a concentration of 1 M. The standard state for gas is a pressure of 1 atm. therefore Qc= 1 or Qp=1

(a) Q < K

When Q < K then the concentration of products are smaller than they would be at equillbrium. the reaction will proceed to the right to decrease. the reactant concentrations and increase the product concentrations until they reach their equilibrium values.

(b) Q > K

When Q > K, then the concentration of the product are larger thant they would be at equilibrium. the reaction will proceed to the left to increase the reactant concentrations and decrease the product concentration until they reach their equilibrium values.

Explain how you might deduce the equilibrium constant for a reaction in which you know the initial concentration of the reactants and products and the equilibrium concentration of only one reactant or product

When the initial concentration of the reactants and products, as well as the equilibrium concentration of one reactant or product are known, the other equilibrium concentration can be deduced from the stoichiometry of the reaction . this is generally done by preparing an ICE table where "I" represents the initial concentration, "C" represents the changes in concentration and "E" represents the equilibrium concentrations. then the equilibrium constant expression is determined from the balanced chemical equation and the equilibrium concentrations are substituted from the ICE Table.