CHE 101 Lecture 5: Chem 101 Chapter 5 Notes

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greenreindeer649

5 Oct 2016

School

University at Buffalo

Department

Chemistry

Course

CHE 101

Professor

Atwood Jim

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Document Summary

Thermochemistry: definitions, calorimetry, enthalpies of formation, hess"s law, energy sources, definitions. Conservation of energy- energy is neither created nor destroyed. Processes that absorb heat are endothermic cold pack. Enthalpy- h- is the heat content of a substance. The enthalpy change for a reaction (at constant pressure) is our focus. Delta h rxn is negative for exothermic and positive for endothermic processes. Guidelines: delta h rxn depends on amount. 2 moles of h2(g) reacting with 1 mole of o2(g) releases. 4 moles of h2 (g) reacting with 2 moles o2(g) gives 967. 2 kj. 2: the value of delta h rxn depends on the state of the reactants and products. 2h2 (g) + o2(g) 2h2o (l) delta h= 571. 0 kj. Electrical potential energy is given by e q1q2. Work- energy to move object against a force. Heat capacity is the amount of heat required to raise an object"s temperature 1k. Specific heat is the heat capacity of 1g of a substance.

Related Questions

At constant pressure, the combustion of 10.0 g of C2Hg(g) releases 518 kJ of heat. What is AH for the reaction given below? 2 C2H6(g) +- 7 O2(g) rightarrow 4 CO2(g) + 6 H2O(l). -779 kJ -1560 kJ -86.1 kJ -3120 kJ Use the information provided to determine Delta H degree r times n for the following reaction: CH4(g) + 3 Cl2(g) rightarrow CHCI3(I) + 3 HCI(g) Delta H degree r times n = ? -217 kJ -335 kJ +662 kJ +117 kJ -151 kJ Choose the reaction that illustrates Delta H degree f for NaHCO3. Na(s) + 2 H(g) + C(s) + 3 O(g) rightarrow NaHCO3 (s) Na(s) + H2(g) + C(s) + O2(g) rightarrow NaHCO3 (s) Na+(aq) + H2O (I) + CO2 (g) rightarrow NaHCO3 (s) Na(s) + 1/2 H2(g) + C(s) + 3/2 O2(g) rightarrow NaHCO3 (s) Na+(aq) + HCO3 -1 (aq) rightarrow NaHCO3 (s) Use the standard reaction enthalpies given below to determine Delta H degree r times n for the following reaction: 4 SO3(g) rightarrow 4 S(s) + 6 O2(g) Delta H degree r times n = ? Given: SO2(g) rightarrow S(s) + O2(g) Delta H degree r times m = +296.8 kJ 2 SO2(g) + O2(g) rightarow 2 SO3(g) Delta H degree r times n = -197.8 kJ -494.6 kJ -791.4 kJ 1583 kJ -293.0 kJ -692.4 kJ Which of the following statements is TRUE? State functions do not depend on the path taken to arrive at a particular state. Energy is neither created nor destroyed, excluding nuclear reactions. Delta Hr times r can be determined using constant pressure calorimetry. Delta H r times n can be determined using constant volume calorimetry. All of the above are true. How much energy is evolved during the formation of 98.7 g of Fe, according to the reaction below? Fe2O3(s) + 2 Al(s) rightarrow Al2O3(s) + 2 Fe(s) Delta H degree r times n = 852 kJ 01.51 times 103 kJ 241 kJ 0482 kJ 4.20 x 103 kJ 753 kJ Given w = 0, an endothermic reaction has the following. - Delta H and + Delta E Delta H and -Delta E - Delta H and -Delta E + Delta H and +Delta E Which of the following substances (with specific heat capacity provided) would show the greatest temperature change upon absorbing 100.0 J of heat? 10.0 g ethanol, Celharol = 2.42 J/g degree C 10.0 g Ag, CAg = 0.235 J/g degree C 10.0 g Au, CAu = 0.128 J/g degree C 10.0 g Fe, CFe = 0.449 J/g degree C 10.0 g H2O, CHO = 4.18J/g degree C Which of the following processes is endothermic? a hot cup of coffee (system) cools on a countertop the vaporization of rubbing alcohol the chemical reaction in a "hot pack" often used to treat sore muscles the freezing of water the combustion of propane

Show transcribed image text At constant pressure, the combustion of 10.0 g of C2Hg(g) releases 518 kJ of heat. What is AH for the reaction given below? 2 C2H6(g) +- 7 O2(g) rightarrow 4 CO2(g) + 6 H2O(l). -779 kJ -1560 kJ -86.1 kJ -3120 kJ Use the information provided to determine Delta H degree r times n for the following reaction: CH4(g) + 3 Cl2(g) rightarrow CHCI3(I) + 3 HCI(g) Delta H degree r times n = ? -217 kJ -335 kJ +662 kJ +117 kJ -151 kJ Choose the reaction that illustrates Delta H degree f for NaHCO3. Na(s) + 2 H(g) + C(s) + 3 O(g) rightarrow NaHCO3 (s) Na(s) + H2(g) + C(s) + O2(g) rightarrow NaHCO3 (s) Na+(aq) + H2O (I) + CO2 (g) rightarrow NaHCO3 (s) Na(s) + 1/2 H2(g) + C(s) + 3/2 O2(g) rightarrow NaHCO3 (s) Na+(aq) + HCO3 -1 (aq) rightarrow NaHCO3 (s) Use the standard reaction enthalpies given below to determine Delta H degree r times n for the following reaction: 4 SO3(g) rightarrow 4 S(s) + 6 O2(g) Delta H degree r times n = ? Given: SO2(g) rightarrow S(s) + O2(g) Delta H degree r times m = +296.8 kJ 2 SO2(g) + O2(g) rightarow 2 SO3(g) Delta H degree r times n = -197.8 kJ -494.6 kJ -791.4 kJ 1583 kJ -293.0 kJ -692.4 kJ Which of the following statements is TRUE? State functions do not depend on the path taken to arrive at a particular state. Energy is neither created nor destroyed, excluding nuclear reactions. Delta Hr times r can be determined using constant pressure calorimetry. Delta H r times n can be determined using constant volume calorimetry. All of the above are true. How much energy is evolved during the formation of 98.7 g of Fe, according to the reaction below? Fe2O3(s) + 2 Al(s) rightarrow Al2O3(s) + 2 Fe(s) Delta H degree r times n = 852 kJ 01.51 times 103 kJ 241 kJ 0482 kJ 4.20 x 103 kJ 753 kJ Given w = 0, an endothermic reaction has the following. - Delta H and + Delta E Delta H and -Delta E - Delta H and -Delta E + Delta H and +Delta E Which of the following substances (with specific heat capacity provided) would show the greatest temperature change upon absorbing 100.0 J of heat? 10.0 g ethanol, Celharol = 2.42 J/g degree C 10.0 g Ag, CAg = 0.235 J/g degree C 10.0 g Au, CAu = 0.128 J/g degree C 10.0 g Fe, CFe = 0.449 J/g degree C 10.0 g H2O, CHO = 4.18J/g degree C Which of the following processes is endothermic? a hot cup of coffee (system) cools on a countertop the vaporization of rubbing alcohol the chemical reaction in a "hot pack" often used to treat sore muscles the freezing of water the combustion of propane

ambermarten481

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!

Practice problems for exam 2 ______________

Useful Information:

h=6.626Ã10-34JÂ·s.; c=3.0Ã108 m/sec; E=hï® ; E= hc , ï¬ = h/mv; 1J = 1 kg-m2/s2 ï¬

mass of electron = 9.11 Ã 10-28 g, ïE= q + w ; 1 cal = 4.184 Joules Please Show all Work

1. Which of the following substances have standard heats of formation that are equal to zero by definition (circle your answers): H2(g), H(g), O3(g), H2O(s), H2O(l), Hg(l), Hg(s), Hg(g).

2. Limestone stalactites are formed in the reaction: Ca2+(aq) + HCO3-(aq) ï CaCO3(s) + CO2(g) +

H2O(l)
If one mole of CaCO3 is produced at 298 K under one atmosphere of pressure, the reaction performs 590 calories of expansion work, pushing back the atmosphere as CO2 is formed. At the same time, 9310 calories of heat are absorbed from the environment. What is ïE in Kcal/mole for CaCO3.

3. What is the minimum wavelength of light in AÌ (1 AÌ = 10-8 cm) needed to provide enough energy per quantum to rupture the chemical bond in hydrogen iodide (HI). The bond dissociation energy of HI is 71.4 Kcal/mole.

4. Sketch the shape and orientation of the following types of orbitals: s, px, dxy, dz2, dx2-y2

5. Give the values of (n) , (l) and (ml) for each orbital in the 4p subshell.

6. Write the complete electron configuration for the following: Ti 2+_____________________________________ Cr_______________________________________

N______________________________________

7. Calculate the standard enthalpy of formation ( ï Ho) for diamond from graphite [i.e. C (graphite) ï C (diamond)] given that:

C (graphite) + O2 ï CO2 (g) ( ï Ho = -393.5 KJ/mole) C (diamond)] + O2 ï CO2 (g) ( ï Ho = -395.4 KJ/mole)

If 1.0g of graphite is converted to diamond, what is the energy change? Is this an endothermic or exothermic reaction?

8. An 160 pound astronaut on his way to Mars is buzzing along at 10,000 miles per hour. (a) Express his weight in grams (one pound = 454 grams) so that you can calculate the astronautâs wavelength (1mile/hour = 44.7 cm/sec)

(b) Suppose the astronaut detects outside his spacecraft a proton (m=1.7 x 10-24 g) from a âsolar windâ moving at exactly the spacecraft velocity. What is the proton wavelength is in AÌ (1 AÌ = 10-8 cm.

9. What is the maximum number of electrons that can occupy each of the following subshells? a) 3d_________________ b) 1s____________________ c) 2p ____________________

10. Identify the element represented by the following electronic configuration.

a) [Ne] 3s2____________________

b) What is the electron configuration for the first excited state of this atom.______________

11. Determine the number of valence electrons for each element.
(a) Br___________ (b) Na _________ (c) Sn __________

12. 175 g of Fe at 15.0oC is mixed with 225 g of H2O at 95.0oC. What is the final temperature of the mixture? The specific heats of iron= 0.448 J/g oC and water = 4.184 J/g oC). (keep in mind the following: heat gained + heat lost = 0 and q=mass x heat capacity x ïT)

13. (5 pts) Calculate values of ÎHrxn for the following reactions: CS2(g) + 3O2(g) ï® CO2(g) + 2SO2(g)

The heat of formation for the following substances is given in kJ/mol:

CS2 CO2 SO2 117.4 -393.51 -296.83

14. (6 pts) Use the electron configuration of Li and Be and determine which element has the greatest second ionization energy. Defend your answer.

15. Mark beside each of the following processes either âexoâ or âendoâ according to whether you think the process will release heat or absorb heat.

a. Ca(g) ï Ca(g)+2 + 2e-
b. I(g)+1e-ï I(g)-1
c. Ca(g)+2 + S(g)-2 ï CaS(s) d. I2(g)ï 2I(g)

( ) ( ) ( ) ( )

16. (6 pts) In each of the following pairs, which of the two species is larger?
a) O-2 or Na+ b) Ti+4 or Ti+2 c) B or C d) N or N-3

17. Write down the Lewis dot structure for the following (a) N_______________ (b) Ne________________

18. THE BORN HABER CYCLE: I may have a problem on the Born Haber cycle. Please check my lecture notes to see how to set up the process and then calculate the lattice energy from the various thermodynamic quantities such as in the NaCl example below;

ï H ï¯ f NaCl = -411KJ

Na(s) ï® Na(g) ï H =108KJ
1â2 Cl2 ï® Cl(g) ï H = 122KJ Ionization Energy of Na ï H = 496 KJ Electron affinity of Cl ï H = -349KJ

CHE 101 Lecture 5: Chem 101 Chapter 5 Notes

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