Write the expression for K c for the following reactions. In each case indicate whether the reaction is homogeneous or heterogeneous. (a) 3 NO(g) ⇌ N 2 O(g) + NO 2 (g) (b) CH 4 (g) + 2 H 2 S(g) ⇌ CS2(g) + 4 H 2 (g) (c) Ni(CO) 4 (g) ⇌ Ni(s) + 4 CO(g) (d) HF(aq) ⇌ H + (aq) + F - (aq) (e) 2Ag(s) + Zn 2+ (aq) ⇌ 2 Ag + (aq) + Zn(s) (f) H 2 O(l) ⇌ H + (aq) + OH - (aq) (g) 2 H 2 O(l) ⇌ 2 H + (aq) + 2 OH - (aq)

Hello everyone today. We are being given the fallen chemical reaction and asked to provide the case expression as well as determine if it is homogeneous or heterogeneous. And so we have the following chemical equation here. So the first thing we wanna do is when writing our case expressions, we're gonna write K. C. Is equal to the concentration of our products over the concentration of our reactant. For Casey expressions. It's also important to note that we don't include solids or liquids. So we don't include solids or liquids. And so when writing our first product out we see that this mercury oxide is in a solid form. So we don't include it. And instead we're going to write a one in its place. The only reactant that's in the gaseous form is this molecular oxygen or 02. So we're just gonna write oh two there. And this will be our K. C. Expression now to determine if it is homogeneous or heterogeneous. We simply have to look at the states of matter for each reactant and product. Our first reaction is in a liquid form. Our second react is in the gas form and our product is in the solid form. So since each of these are indifferent phases, we're going to say that this is a heterogeneous reaction. So it's a heterogeneous reaction because the states of matter for our reactant and products are different. I hope this helped until next time

Ch.15 - Chemical Equilibrium

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Brown 14th Edition

Ch.15 - Chemical Equilibrium

Problem 15e

Chapter 15, Problem 15e

Write the expression for K_c for the following reactions. In each case indicate whether the reaction is homogeneous or heterogeneous.
(a) 3 NO(g) ⇌ N₂O(g) + NO₂(g)
(b) CH₄(g) + 2 H₂S(g) ⇌ CS2(g) + 4 H₂(g)
(c) Ni(CO)₄(g) ⇌ Ni(s) + 4 CO(g)
(d) HF(aq) ⇌ H⁺(aq) + F^-(aq)
(e) 2Ag(s) + Zn²⁺(aq) ⇌ 2 Ag⁺(aq) + Zn(s)
(f) H₂O(l) ⇌ H⁺(aq) + OH^-(aq)
(g) 2 H₂O(l) ⇌ 2 H⁺(aq) + 2 OH^-(aq)

Verified step by step guidance

Identify the reactants and products in the reaction. For the given reaction, the reactants are Ag(s) and Zn2+(aq), and the products are Ag+(aq) and Zn(s).

Write the expression for the equilibrium constant, Kc, using the concentrations of the aqueous species. For each species, raise the concentration to the power of its stoichiometric coefficient in the balanced equation.

Since Ag(s) and Zn(s) are solids, their activity is considered to be 1 and they do not appear in the expression for Kc.

The expression for Kc is therefore: Kc = [Ag+]^2 / [Zn2+]

Determine the type of reaction: Since the reaction involves both solid and aqueous species, it is a heterogeneous reaction.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Equilibrium Constant (Kc)

The equilibrium constant, Kc, is a numerical value that expresses the ratio of the concentrations of products to the concentrations of reactants at equilibrium for a given reaction at a specific temperature. It is calculated using the formula Kc = [products]^[coefficients] / [reactants]^[coefficients]. Understanding Kc is essential for predicting the direction of a reaction and the extent to which reactants are converted to products.

Homogeneous vs. Heterogeneous Reactions

Homogeneous reactions occur when all reactants and products are in the same phase (solid, liquid, or gas), while heterogeneous reactions involve reactants and products in different phases. This distinction is important because it affects how concentrations are expressed in the Kc expression. In heterogeneous reactions, only the concentrations of species in the aqueous or gaseous phase are included in the Kc expression, while solids and liquids are omitted.

Phase Representation in Reactions

In chemical equations, the physical state of each substance is indicated by symbols: (s) for solid, (l) for liquid, (g) for gas, and (aq) for aqueous solutions. This representation is crucial for determining the correct form of the Kc expression. For example, in the given reaction, only the aqueous ions are included in the Kc expression, as the solid metals do not contribute to the equilibrium concentrations.

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Related Practice

Textbook Question

Suppose that the gas-phase reactions A → B and B → A are both elementary reactions with rate constants of 4.7×10⁻³ s⁻¹ and 5.8×10⁻¹ s⁻¹, respectively. (a) What is the value of the equilibrium constant for the equilibrium A(g) ⇌ B(g)? (b) Which is greater at equilibrium, the partial pressure of A or the partial pressure of B?

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Textbook Question

The equilibrium constant for the dissociation of molecular iodine, I₂(g) ⇌ 2 I(g), at 800 K is K_c = 3.1 × 10^–5. (a) Which species predominates at equilibrium I₂ or I?

Textbook Question

The equilibrium constant for the dissociation of molecular iodine, I₂(g) ⇌ 2 I(g), at 800 K is K_c= 3.1×10⁻⁵. (b) Assuming both forward and reverse reactions are elementary reactions, which reaction has the larger rate constant, the forward or the reverse reaction?

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Textbook Question

Write the expressions for K_c for the following reactions. In each case indicate whether the reaction is homogeneous or heterogeneous.

(a) 2 O₃(g) ⇌ 3 O₂(g)

(d) C(s) + 2 H₂(g) ⇌ CH₄(g)

(e) 4 HCl(aq) + O₂(g) ⇌ 2 H₂O(l) + 2 Cl₂(g)

(f) 2 C₈H₁₈(l) + 25 O₂(g) ⇌ 16 CO₂(g) + 18 H₂O(g)

(g) 2 C₈H₁₈(l) + 25 O₂(g) ⇌ 16 CO₂(g) + 18 H₂O(l)

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Textbook Question