CHEM 101DL Study Guide - Midterm Guide: Tetrafluoromethane, Methanol, Oxygen Difluoride

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Chemistry 10D1L

Dr. T. Woerner

Summer I, 2018

Thermodynamics Problems - Solutions

1. The combustion of 1.000 g of ethyl alcohol, C2H5OH(

), in a bomb calorimeter (at

constant volume) evolves 29.62 kJ of heat at The products of the combustion are

CO2(g) and H2O(

). The molecular weight of ethyl alcohol is 46.06 g/mole. a) What is

for the combustion of one mole of ethyl alcohol? b) Write the balanced equation for

the reaction. What is the value of for the combustion? c) Use values from the

attached table and your answer to part (b) above to calculate for ethyl alcohol.

a) a bomb calorimeter measures directly as qv = . 1.000 g C2H5OH(!) gives off

29.62 kJ of heat. There are 46.06 g/m for C2H5OH(!).

Thus =

Note: the (–) sign indicated that heat has been given off.

b) C2H5OH(!) + 3O2(g) 2CO2(g) + 3H2O(!)

25oC

ΔEo

"– 29.62 kJ

g #

$ !

"46.06 g

mole #

$ = – 1364.3 kJ

mole

ΔHo = ΔEo + ΔnRT

here Δn = (2 moles of gaseous CO2 product) − (3 moles of gaseous O2 reactant)

∴ Δn = – 1

So, ΔHo = $

%– 1364.30 kJ

mole &

' + (– 1) $

%8.314X10−3 kJ

K . mole &

'(298 K)

∴ ΔHo = – 1366.78 kJ

mole

ΔHo = ∑ ΔHo

f (products) − ∑ ΔHo

f (reactants)

ΔHo = [3(ΔHo

f H2O(l)) + 2(ΔHo

f CO2(g))] − [3(ΔHo

f O2(g)) + ΔHo

f C2H5OH(l)]

– 1366.78 = $

&3 '

(– 286.10 kJ

mole )

* + 2 '

(– 393.51 kJ

mole )

- − $

&3 '

(0 kJ

mole )

* + (ΔHo

f C2H5OH(l)) +

ΔHo

f C2H5OH(l) = – 278.54 kJ

mole

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2. Calculate for the combustion of octane, C8H18(

). The products of the

combustion reaction are CO2(g) and H2O(

) at . The value of for this reaction

at is –5470.71 kJ/mole of octane.

C8H18(!) + 12.5O2(g) 8CO2(g) + 9H2O(!)

Note: if this balancing result is bothersome for you due to the fraction, you could double

all the coefficients, but be aware that the reaction would then be written for 2 moles of

octane.

3. Calculate and for the reaction of Ca3P2(s) with H2O(

). The reaction

produces Ca(OH)2(s) and PH3(g). The enthalpy of formation values needed for the

calculation may be found in the attached table.

Ca3P2(s) + 6H2O(!) 3Ca(OH)2(s) + 2PH3(g)

4. For the reaction

25oC

ΔEo = ΔHo – ΔnRT

ΔEo = – 5470 kJ

mole – (– 4.5) "

#8.314X 10–3

K mole $

%(298 K)

ΔEo = – 5470 kJ

mole + 11.15 kJ

mole = – 5458. 85 kJ

mole

ΔHo=ΔHf

o(products) −

∑ΔHf

o(reactants)

∑

ΔHo=2 5.47 kJ

mole

( +3−968.59 kJ

mole

(

)

. −6−286.10 kJ

mole

( +−504.17 kJ

mole

(

)

=−674.06 kJ

mole

ΔEo=ΔHo− ΔnRT

ΔEo=−674.06 kJ

mole −2

( )

8.314 ×10−3kJ

K⋅mole

(

) 298K

( )

=−679.02 kJ

mole

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Document Summary

Thermodynamics problems - solutions: the combustion of 1. 000 g of ethyl alcohol, c2h5oh(! The products of the combustion are constant volume) evolves 29. 62 kj of heat at. The molecular weight of ethyl alcohol is 46. 06 g/mole. a) what is. E for the combustion of one mole of ethyl alcohol? b) write the balanced equation for the reaction. H o for the combustion? c) use values from the attached table and your answer to part (b) above to calculate. Ho f for ethyl alcohol: a bomb calorimeter measures. $ = 1364. 3 directly as qv = " 29. 62 mole # kj g kj mole o. Note: the ( ) sign indicated that heat has been given off: c2h5oh(!) Ho = eo + nrt here n = (2 moles of gaseous co2 product) (3 moles of gaseous o2 reactant) K . mole & kj mole & kj mole. Ho = 1366. 78 f (reactants) f (products) ho.

Related Questions

HERE IS HOW THIS IS GOING TO WORK! IF YOU ANSWER THE QUESTIONS IWILL GIVE YOU THE 3K POINTS + MORE AFTER I REPOST IT.

2. The amount of heat involved in the synthesis of 1 mole of acompound from its elements, with all substances in their standardstates at 25*C, is called _________.

3. What is a valid unit for specific heat?

4. Use Hess's Law to find the heat of reaction in the examplebelow.

N2O4 (g) ----> 2NO2 (g)

Given that:

N2O4 (g) ----> N2 (g) + 2O2 (g) (Delta H =-9.7kJ)

2NO2 (g) ----> 2O2(g) + N2(g) ( Delta H= -67.7kJ)

5. Use Hess's Law to find the heat of reaction in the examplebelow. (Example doesn't exist btw.)

6. (Delta H) for the formation of rust (Fe2O3) is -826 kJ/mol. Howmuch energy is involved in the formation of 5 grams ofrust?

7. How many kilocalories of heat are required to raise thetemperature of 50g of aluminum from -5*C to 35*C? (Specific heat ofAluminum = 0.21 cal/g*C)

8.Calculate the (Delta H) for this reaction:

Zn(s) + Cu (2+ ion)(aq) ---> Zn(2+) + Cu(s)

(Delta H) for Cu(2+) = +64.4 kJ/Mol; (Delta H) for Zn(2+) = -152.4kJ/mol

9. The following equation shows the reaction that occurs whennitroglycerine explodes.

4C3H5O9N3 ----> 12CO2 + 6N2 + O2 +10H2O + 1725 Kcal

Is this reaction exothermic , endothermic, a combustion reaction ,or a combination reaction?

10. What does it mean for ammonia, (NH3) to have a (Delta H f) =-46 kJ/mol?

(for example: Define heat of formation. What does a negative heatof formation mean? what do the units of kJ/mol mean?)

11. What is the maximum amount of KCl that can dissolve in 500g ofwater?

(solubility of KCl is 34 g/ 100g of water at 20*C)

12.List the ways(operations) that can help make a substancedissolve faster in a solvent?

13. If a crystal added to an aqueous solution causes many particlesto come out of solution, the original solution was (saturate,unsaturated, supersaturated).

14. What is the number of moles of solute in 165 mL of a 0.82 Msolution?

15. What mass of NaCl is needed to make 350 mL of a 1.00 Msolution?

16. Colligative properties depend upon...

17. If one mole of each of these solutes in added to the sameamount of water, which solution has the highest boiling point?(glucose, aluminum sulfate, magnesium acetate, copper (I)chloride)

18. When an acid reacts with a base, what compounds areformed?

19. If the [H+] in a solution is 1x10^(-13) mol/L, what is the[OH-]?

20. If the [OH-] = 1x10^-6 mol/L, what is the pH of thesolution?

21. For a solution to be considered acidic what must be thehydrogen-ion concentration?

22. Which of the following represents a Bronsted-Lowry conjugateacid-base pair?

a) SO3(2-) and SO2 b) CO3(2-) and CO c) H3O and H2 d) NH4(+) and NH3

23. With solutions of "strong" acids and "strong" bases, the word"strong" refers to ...

24. What are the products of Al(OH)3 + H2CO3?

25.What is the concentration of hydrochloric acid if 5.0 mL of acidis neutralized by 30.0 mL of 2.00M sodium hydroxide.

26. At equilibrium, what is the rate of production of reactantscompared with the rate of production of products?

27. What is the equilibrium constant for the following reaction2SO3 ---> 2SO2 + O2

28. How does an increase in pressure affect the following reaction?2SO3 (g) --> 2SO2(g) +O2(g)

29.What stresses would shift the reaction to the right?

2SO3(g) ==> 2SO2(g) + O2(g)

30. The Keq of a reaction 4.9 x 10^(-7). Are products or reactantsfavored at equilibrium?

31. In which of these systems is the entropy decreasing?

a) air escaping from a tire b) snow melting c) a gas condensing d) salt dissolving inwater

32. If an atom is reduced in a redox reaction, what must occur toanother atom in the system?

33. Identify the oxidizing agent in the following reaction: 2Na + S---> Na2S

34. What are transferred in an oxidation -reductionreaction?

35. Give the oxidation number for each atom in KMnO4.

36. Which atom has a change in oxidation number of +4 in thefollowing reaction?

K2Cr2O7 + H2O + S ----> KOH + Cr2O3 +SO2

37. What is the oxidation number of sulfur in each of the following:

a. SO3 c.SO2(2-)

b. Na2SO4 d. S2O4 (2-)

38.Fe(3+) ----> Fe represents oxidation, reduction, orhydrolysis?

39. When the half reactions Br2+ 2e- -----> 2Br- and Na---->e- + Na(+) are combined the balanced redox equation is_____________________ ( WRITE the BALANCED REDOX eq)

40. To balance the oxygen and hydrogen for a redox reaction thattakes place in basic solution, it is necessary to use whichsubstance?

41. What particle completes this nuclear equation? 55/25 Mn + 2/1 H====> _____ +2 1/0 n

42. The half-life of tungsten-182 (182/74 W) is 1.1x10^(17) years.How long would it take for a 376.2 kg sample to decay until only123.0 grams remain?

43. After 3 days, the quantity of certain radioisotope is reducedfrom 13.6 grams to 1.9 grams. Calculate the half-life of theisotope.

44. What is the name of the compound having the formulaC8H18.

45. What is the name of the following compound:

CH3---CH2----CH---CH2--C

I \

CH3 OH

46. What is an isomer? Give an isomer of hexane (C6H14) and drawit's structure.

47. What is the name of the hydrocarbons with double covalentbonds?

48. Draw the stucture for 3-methylbutanoic acid.

49. Draw the structure for methylbenzene?

50. What is the name of the following compound:

CH3----C-----CH3

CH3

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CHEM 101DL Study Guide - Midterm Guide: Tetrafluoromethane, Methanol, Oxygen Difluoride

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