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Balancing Chemical Equations

#### Q. Enter a balanced chemical equation for the reaction between aluminum metal and liquid bromine. Express your answer as a chemical equation. Identify all of the phases in your answer.

Solved • Mar 10, 2020

Physical & Chemical Changes

#### Q. Which change is a chemical change? a) the corrosion of iron b) the forming of log in the morning c) the dissolving of sugar

Solved • Mar 10, 2020

Gibbs Free Energy

#### Q. Chlorine gas, Cl2(g), reacts with nitric oxide, NO(g), to form nitrosyl chloride, NOCl(g), via the reaction Cl2(g) + 2NO(g) ⇌ 2NOCl(g) The thermodynamic data for the reactants and products in the reaction are given in the following table: The diagram below serves as a pictorial depiction of the relationship between the free energy and standard free energy in the equation ΔG = ΔG° + RT ln Q. Point A is at standard conditions, which means all reagents have a partial pressure of 1 atm, as shown in the equation below point A. Points B and C are at nonstandard conditions. Point X indicates the point at which equilibrium lies. The axis labeled Q refers to the reaction quotient. The actual value of Q at the point of equilibrium is Kp, which is the equilibrium constant at 298 K. Using standard free energy of formation values given in the introduction, calculate the equilibrium constant Kp of the reaction Cl29g) + 2NO(g) ⇌ 2NOCl(g) The standard free energy of the reaction represents the drive the reaction has under standard conditions to move toward equilibrium from point A to point X n the diagram. Express the equilibrium constant numerically using three significant figures.

Solved • Mar 2, 2020

Gibbs Free Energy

#### Q. Consider these hypothetical chemical reactions: 1. A ⇌ B, ΔG = 12.0 kJ/mol 2. B ⇌ C, ΔG = -30.8 kJ/mol 3. C ⇌ D, ΔG = 8.60 kJ/mol What is the energy, ΔG, for the overall reaction, A ⇌ D? Express your answer with the appropriate units. What can be said about the favorability of the overall reaction? a) This reaction is thermodynamically favorable. b) This reaction is thermodynamically neutral. c) This reaction is thermodynamically unfavorable. d) There is not enough information to determine thermodynamic favorableness.

Solved • Mar 2, 2020

Gibbs Free Energy

#### Q. Chlorine gas, Cl2(g), reacts with nitric oxide, NO(g), to form nitrosyl chloride, NOCl(g), via the reaction Cl2(g) + 2NO(g) ⇌ 2NOCl(g) The thermodynamic data for the reactants and products in the reaction are given in the following table: The diagram below serves as a pictorial depiction of the relationship between the free energy and standard free energy in the equation ΔG = ΔG° + RT ln Q. Point A is at standard conditions, which means all reagents have a partial pressure of 1 atm, as shown in the equation below point A. Points B and C are at nonstandard conditions. Point X indicates the point at which equilibrium lies. The axis labeled Q refers to the reaction quotient. The actual value of Q at the point of equilibrium is Kp, which is the equilibrium constant at 298 K. Calculate the free energy ΔG at 25 °C for the nonstandard conditions at point B where the reaction quotient Q is 2.75 x10^-5. Express your answer numerically in kilojoules.

Solved • Mar 2, 2020

Gibbs Free Energy

#### Q. Firefly luciferase is the enzyme that allows fireflies to illuminate their abdomens. Because this light generation is an ATP-requiring reaction, firefly luciferase can be used to test for the presence of ATP. In this way, luciferase can test for the presence of life. The coupled reactions are 1. luciferin + O2 ⇌ oxyluciferin + light 2. ATP ⇌ AMP + PPi ΔG°= -31.6 kJ/mol If the overall ΔG° of the coupled reaction is -7.70 kJ/mol, what is the equilibrium constant, K, of the first reaction at 25 °C? Express your answer numerically.

Solved • Mar 2, 2020

Gibbs Free Energy

#### Q. When propanol (CH3CH2CH2OH) is combusted, such as when in a gasoline blend, the following reaction occurs: 2CH3CH2CH2OH(l) + 9O2(g) → 6CO2(g) + 8H2O(g) Based on the standard free energies of formation given in the table below, what is the standard free energy change for this reaction? Express your answer to one decimal place and include the appropriate units.

Solved • Mar 2, 2020