For the equilibrium PH 3 BCl 3 (𝑠) ⇌ PH 3 (𝑔) + BCl 3 (𝑔) 𝐾 𝑝 = 0.052 at 60 °C. (b) After 3.00 g of solid PH 3 BCl 3 is added to a closed 1.500-L vessel at 60 °C, the vessel is charged with 0.0500 g of BCl 3 (𝑔). What is the equilibrium concentration of PH 3 ?

Hello everyone today. We are being given the following problem and asked to solve for it. So nitrogen nitrogen dioxide decomposed into nitric oxide and oxygen gas. And the following chemical reaction is given to us of that process a 0.6 most sample of nitrogen dioxide was placed in a one liter flask and allowed to reach equilibrium. What is the equilibrium concentration of oxygen gas? If our equilibrium constant is equal to 1.2 times 10 to the negative fifth. So the first thing we wanna do is we want to calculate our case the expression and that is going to have our products, the concentration of our products in the numerator over our concentration of our reactant and the denominator. With our case expressions, we with our Casey expressions, we only pay attention to the gas just forms of these substances no solves or liquids and with that we see that we have two products. We have nitric oxide. We're gonna write in o in brackets there and since we have a two coefficient for that, we're going to make that expanded to, we're going to multiply the other product molecular oxygen or oxygen gas. And then for our reactant we only have one, it's going to be nitrogen dioxide and we're gonna write that in brackets. And so that's our K. C. Expression. Next. We're going to construct our ice chart. So before we do that we just want to write our chemical equation over again and then we're going to write I C. E. The I stands for the initial concentrations. The C stands for the change in concentrations and the is just the equilibrium. So our initial concentration of our nitrogen dioxide as given to us in the question stem is going to be 0.6 molar. And so how did we get that? So malaria t is simply moles over liters. The question stem gave us 0.6 moles and it also gave us one leader And that would give us our .6 moles. Of course our initial concentrations for the products will be zero each. Since we are taking away from our reactive we're gonna denote that by the change by being negative X. And positive X for the products. And as noted before for equilibrium, we're going to just take I and subtract it by our seed, the equilibrium. So we're gonna have 0.6 minus X. For the first one, nitrogen dioxide for our first product, we're gonna have to X since we have two of those nitric oxide molecules. And we're simply just gonna have an X. For oxygen. And so working this into our expression, we want to check and see if this X value is negligible or not. And so to do that, we're gonna take our Casey expression which would be equal to our 0.6 Divided by our 1.2 Times 10 to the -5. And it wasn't mentioned before, but we have our concentration of nitrogen dioxide over RKC RKc constant. And so what we saw for that, we see that we have a magnitude of 55,000 to 500. And therefore, since the value is so insignificant, we can say that X is ignored. So when we write out our K. C equation, we take our K. C value, which is 1.2 times 10 to the negative fifth. And we're going to equal that too. Our concentrations of our variables that we just found. And so in the numerator, we're going to have to X squared times X for our products here. And they were going to place that over our 0.6 for our reacted there. This equation can simplify itself to 7.2 times 10 to the negative six is equal to four X. Cute solving for X, which is also the concentration for our oxygen at equilibrium, we get a value of 0.10 moller as our answer. I hope this helped. And until next time.

Ch.15 - Chemical Equilibrium

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Brown 14th Edition

Ch.15 - Chemical Equilibrium

Problem 80b

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Chapter 15, Problem 80b

For the equilibrium PH₃BCl₃(𝑠) ⇌ PH₃(𝑔) + BCl₃(𝑔) 𝐾_𝑝 = 0.052 at 60 °C. (b) After 3.00 g of solid PH₃BCl₃ is added to a closed 1.500-L vessel at 60 °C, the vessel is charged with 0.0500 g of BCl₃(𝑔). What is the equilibrium concentration of PH₃?

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Convert the mass of BCl_3(g) to moles using its molar mass.

Set up an ICE (Initial, Change, Equilibrium) table to track the changes in moles of each species.

Use the initial moles of BCl_3(g) and the stoichiometry of the reaction to express the changes in moles of PH_3(g) and BCl_3(g) in terms of a variable x.

Write the expression for K_p in terms of the partial pressures of PH_3(g) and BCl_3(g), and relate these to their concentrations using the ideal gas law.

Solve the K_p expression for x, which represents the change in moles of PH_3(g), and calculate the equilibrium concentration of PH_3(g) using the volume of the vessel.

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Key Concepts

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

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. In this scenario, the equilibrium constant (Kp) quantifies the ratio of the partial pressures of the gaseous products to that of the solid reactant, indicating the extent of the reaction at a given temperature.

Equilibrium Constant (Kp)

The equilibrium constant (Kp) is a dimensionless value that expresses the relationship between the concentrations (or partial pressures) of reactants and products at equilibrium. For the reaction PH3BCl3(s) ⇌ PH3(g) + BCl3(g), Kp = 0.052 indicates that at equilibrium, the concentration of gaseous products is relatively low compared to the solid reactant, reflecting the position of equilibrium.

Stoichiometry and Concentration Calculations

Stoichiometry involves using the coefficients of a balanced chemical equation to relate the amounts of reactants and products. In this problem, the initial amounts of PH3BCl3 and BCl3 must be converted to moles, and then the changes in concentration due to the reaction must be calculated to determine the equilibrium concentration of PH3, taking into account the volume of the vessel.

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Textbook Question

Consider the hypothetical reaction A(𝑔) ⇌ 2 B(𝑔). A flask is charged with 0.75 atm of pure A, after which it is allowed to reach equilibrium at 0°C. At equilibrium, the partial pressure of A is 0.36 atm. (c) What could we do to maximize the yield of B?

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Textbook Question

As shown in Table 15.2, the equilibrium constant for the reaction N2(𝑔) + 3 H₂(𝑔) ⇌ 2 NH₃(𝑔) is 𝐾_𝑝= 4.34×10⁻³ at 300°C. Pure NH3 is placed in a 1.00-L flask and allowed to reach equilibrium at this temperature. There are 1.05 g NH₃ in the equilibrium mixture. (b) What was the initial mass of ammonia placed in the vessel?

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Open Question

For the equilibrium 2 IBr(g) ⇌ I2(g) + Br2(g), Kp = 8.5 * 10^-3 at 150 _x001F_C. If 0.025 atm of IBr is placed in a 2.0-L container, what is the partial pressure of all substances after equilibrium is reached?

Open Question

Solid NH4SH is introduced into an evacuated flask at 24 _x001F_C. The following reaction takes place: NH4SH(s) ⇌ NH3(g) + H2S(g). At equilibrium, the total pressure (for NH3 and H2S taken together) is 0.614 atm. What is Kp for this equilibrium at 24 _x001F_C?

Textbook Question

A 0.831-g sample of SO₃ is placed in a 1.00-L container and heated to 1100 K. The SO₃ decomposes to SO₂ and O₂: 2SO₃(𝑔) ⇌ 2 SO₂(𝑔) + O₂(𝑔) At equilibrium, the total pressure in the container is 1.300 atm. Find the values of 𝐾_𝑝 and 𝐾_𝑐 for this reaction at 1100 K.

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Textbook Question

Nitric oxide (NO) reacts readily with chlorine gas as follows: 2 NO(𝑔) + Cl₂(𝑔) ⇌ 2 NOCl(𝑔) At 700 K, the equilibrium constant Kp for this reaction is 0.26. Predict the behavior of each of the following mixtures at this temperature and indicate whether or not the mixtures are at equilibrium. If not, state whether the mixture will need to produce more products or reactants to reach equilibrium. (b) P_NO = 0.12 atm, P_Cl2 = 0.10 atm, P_NOCl = 0.050 atm

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For the equilibrium PH3BCl3(𝑠) ⇌ PH3(𝑔) + BCl3(𝑔) 𝐾𝑝 = 0.052 at 60 °C. (b) After 3.00 g of solid PH3BCl3 is added to a closed 1.500-L vessel at 60 °C, the vessel is charged with 0.0500 g of BCl3(𝑔). What is the equilibrium concentration of PH3?

Verified Solution

Key Concepts

Chemical Equilibrium

Equilibrium Constant (Kp)

Stoichiometry and Concentration Calculations

For the equilibrium PH₃BCl₃(𝑠) ⇌ PH₃(𝑔) + BCl₃(𝑔) 𝐾_𝑝 = 0.052 at 60 °C. (b) After 3.00 g of solid PH₃BCl₃ is added to a closed 1.500-L vessel at 60 °C, the vessel is charged with 0.0500 g of BCl₃(𝑔). What is the equilibrium concentration of PH₃?