CHEM102 Lecture Notes - Lecture 25: Dave Coverly, Endothermic Process, Joule

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champagnemoose566

26 Jun 2015

School

University of Alberta

Department

Chemistry

Course

CHEM102

Professor

Yoram Apelblat

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CHEM102 Full Course Notes

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H2o (s) h2o (l) hfusion > . H2o (l) h2o (g) hevaporation > . H2o (s) h2o (g) hsublimation > . Enthalpy is an extensive property always always always. 2 h2 (g) + o2 (g) 2 h2o (l) H3 = h1 + h2 rxn4 = rxn1 rxn2. Exothermic reaction gas work w = p v. Reactants products + heat q < 0. Reactants + heat products q > 0. Hess"s law if a rxn proceeds in steps, the overall change in h is the algebraic sum of the h"s for the individual steps. H f (o2 (g)) = 0 not on cds! Instead use cds t 10 f = standard enthalpy of formation. (all ions at 1 m). f = formation. Standard state = most stable physical form of the element at 1 atm and a given temperature (often 25 c). Cgraphite (s) not cdiamond (s) 1. 9 kj higher.

Related Questions

Please answer the following questions AND SHOW WORK ifapplicable--I do not understand some of them! (750 value)

1. How many moles of chloride ions are present in 18.4g ofCaCl2?

2. Complete the follow reaction and identify the Bronstedbase:

NaOH (aq) + HCl (aq) ---> ________________

3. A candy bar contains 280 Calories, of which the fat contentaccounts for 120 Calories. What is the energy of the fat content,in kJ?

4. 25 kJ of heat is absorbed and 15 kJ of work is done on thesurroundings. What is /\U?

5. What is the change in internal energy in joules for a systemthat releases 154 J of heat and does 125 J of work on itssurroundings?

6. Ice packs, have lower temperatures when ammonium nitratedissolves in water--which of the following is true of thisreaction?

A. /\H<0, process is exothermic

B. /\H>0, process is exothermic

C. /\H<0, process is endothermic

D. /\H>0, process is endothermic

E. /\H=0, since cold packs are sealed

7. 2SO2 + O2 ----> 2SO3, /\H degrees rxn = -198kJ/mol, howmuch heat is evolved when 600 g of SO2 is burned?

8. Calculate /\H degree rxn for the following reaction:

2H2O2 ---> 2H2O +O2

*Given that /\H degree f [H2O] = -285.8 kJ/mol and /\H dgree f[H2O2] = 187.6 kJ/mol

9. For the following reaction, write the half-reactions, the netreaction, and identify the oxidizing agent:

H2SO4 + Cd(OH)2 ----> 2H2O + CdSO4

THANK YOU!

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.

Combustion of the amino acid glycine NH₂CH₂COOH follows the balanced reaction NH₂CH₂COOH(s) + 9/4O₂ --> 2CO₂(g) + 5/2H₂O(l) + 1/2N₂(g)

The standard enthalpy of combustion of glycine is 981.0 kJmol^-1.

a) For the combustion of 10.0 grams of glycine at T=300.K and at constant pressure of P=1.00 atm, calculate heat evolved q, ÎH, ÎU, and the work done. Assume the work done is irreversible pressure-volume work. Assume the volume change ÎV is determined by În=n(gas, prod) - n(gas, react), the change in the number of moles of gas that occurs in going from reactants to products. Assume all gases behave ideally.

b) Repeat the calculation at T=350K.

You will need the following heat capacities, C_P(JK^-1mol^-1), which you may assume are constant between T=300.0K and T=350.0K:

Glycine(s): 99.20

0₂(g): 29.36

CO₂(g): 37.13

N₂(g): 29.12

H₂O(l): 75.30

CHEM102 Lecture Notes - Lecture 25: Dave Coverly, Endothermic Process, Joule

CHEM102 Full Course Notes

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