CHEM 001 Lecture Notes - Lecture 25: Dynamic Equilibrium, Enthalpy, Partial Pressure

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skywildebeest596

13 Aug 2020

School

College of The Sequoias

Department

Chemistry (CHEM)

Course

CHEM 001

Professor

Rodriguez

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Document Summary

Formation of intermolecular bonds between the solvent and solute molecules; exothermic. Because at constant pressure enthalpy change = heat: h = q. B. hsol = h1 + h2 + h3. Solution formation: heat of solution & heat of hydration. Heat of solution: measures the energy absorbed in: Heat of hydration: measures the energy releases in: Solution gives off heat; temperature of solution is seen to rise. New intermolecular bonds are more stable than the old. New bonds are stronger than the pure substance. Solution absorbs heat; temperature of solution is seen to drop. E. solution formation always has positive entropy. Some of the molecules are liquid, and some have enough kinetic energy (from temperature) to break free from the surface and fly into open space gas molecules. Note: rate of evaporation is temperature dependent and thus stays constant, while condensation rates rise to equilibrate.

Related Questions

D. 1. Silver chloride is not soluble in water. What are the relative strengths of the intermolecular forces between Ag and Ciions and water molecules as compared to the intermolecular forces between water molecules and the forces that hold the silver chloride as a solid? a. The ionic attractions are stronger than the polar covalent bonds between the H' and O ions of the b. The ionic attractions are weaker than the intermolecular forces between the Ag' and Cr ions and water c. The ionic attractions are stronger than the intermolecular forces between the Ag' and Cr ions and water d. The ionic attractions are the same as the intermolecular forces between the Ag and CI ions and water water molecules. molecules. molecules molecules 2. The value of AHsotn for a water soluble compound is +34 kJ moÄ¾1. Which value for this compound would be numerically larger, its lattice energy or its hydration energy? Select the single best answer. step. b. The lattice energy, because it is the endothermic step c. The hydration energy, because it is the exothermic step. d. The lattice energy, because it is the exothermic step. 3, which of the following are reasons why the value of ì¨,on for a gas such as CO2, dissolving in water, is negative? a. When a gas dissolves in a liquid, there is no endothermic step as with the lattice energy of a solid. b. When a gas dissolves in a liquid, there is only an exothermic step as with the lattice energy of a solid. c. The only enthalpy change is the one associated with hydration, and this is always positive. d. The only enthalpy change is the one associated with hydration, and this is always negative. e. When a gas dissolves in a liquid the lattice energy is always higher than the hydration energy, making the net enthalpy always negative. 4. Why is ammonia so much more soluble in water than is nitrogen? a. The triple bond in nitrogen prevents it from dissolving in water. b. Nitrogen has only London forces, while both water and ammonia form hydrogen bonds. c. The molar mass of nitrogen is much larger than the molar mass of ammonia, which reduces its solubility. d. Diatomic molecules are never soluble in water s which agueous solution, if either, is likely to have the highÏr boiling point 50 m Nal or en-Na e au

Q1: At a pressure of 690 mmHg the volume changes from an initial volume 0.5 L to 5 L, calculate the work done in Joules (1 L.atm = 101.3 J).

Q2: Select the state functions

1. E 2. H 3. q 4. T

Q3: When a change of state from gas to liquid (condensation) takes place; X (g) -> X (l), the substance releases 350.1 J of heat energy and does 203.2 J of work on its surroundings. Calculate the change of E for this process.

Q4: Select the correct sign for the change of standard molar enthalpy of formation in a case of an endothermic process.

a) ïHf 0 > 0 (positive)

b) ïHf 0 < 0 (negative)

Q5: A silver (Ag) ring absorbs 8.15 J of energy with a temperature change of 15.0ï°K. The specific heat capacity of Ag is 0.233 J/g K. What is the mass of the ring?

1/ the total volume of hydrogen gass needed to fill the Hindenburge was 2x10^8 liters at 1 atm and 25*C. How Much energy was evolved when it burned ?

H2(g) + .5O2(g) ----> H2O(I) âH* = -286Kj

2/ The heat of formation of iron(III) oxide is -826KJ/mol. Calculate the heat of the reaction when a 55.8 g sample of iron is reacted with an excess of oxygen gas.

4Fe(s) + 3O2(g) -----> 2Fe2O3(s)

3/ the vapor pressure of water at 25*Celcius is 23.8 torr. Determine the mass of glucose( molar mass= 180g/mol) needed to add to 500 grams of water to change the vapor pressure to 23.1 torr.

4/ Consider the reaction H2(g) + .5O2(g) ----> H2O(I) âH*= -286 Kj

which of the following is true?

A/ The reaction is exothermic

B/ The reaction is endothermic

C/ The enthalpy of the products is less than that of the reactants.

D/ Heat is absorbed by the system

E/ The reaction is exothermic and the enthalpy of the products is less than that of the reactants.

CHEM 001 Lecture Notes - Lecture 25: Dynamic Equilibrium, Enthalpy, Partial Pressure

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