Chapter 5: Thermodynamics Worksheet With Answers - Ap Chemistry 2015-2016 (Page 10 of 14) in pdf

Chapter 5: Thermodynamics Worksheet With Answers - Ap Chemistry 2015-2016 Page 10

OH(s) + 7 O

(g) -‐‑ > 6 C O

(g) + 3 H

O(l)

When a 2 .000-‐‑ g ram s ample o f p ure p henol, C

OH(s), i s c ompletely b urned a ccording t o t he e quation

above, 6 4.98 k ilojoules o f h eat i s r eleased. U se t he i nformation i n t he t able b elow t o a nswer t he q uestions

that f ollow.

Standard H eat

of F ormation,

Substance

DH°

; a t 2 5°C

(kJ/mol)

(g)

-‐‑ 3 93.5

O(l)

-‐‑ 2 85.85

OH(s)

(a) Calculate t he m olar h eat o f c ombustion o f p henol i n k ilojoules p er m ole a t 2 5°C.

-‐‑ 3 058 k J/mol

(b) Calculate t he s tandard h eat o f f ormation, D H°

, o f p henol i n k ilojoules p er m ole a t 2 5°C.

-‐‑ 1 60.6 k J/mol

1. How m any j oules a re e quivalent t o 3 7.7 c al?

a) 9.01 J

c) 1.51 J

b) 4 .184 J

d) 158 J

2. The q uantity o f h eat t hat i s n eeded t o r aise t he t emperature o f a s ample o f a s ubstance 1 .00 d egree i s

called i ts

a) h eat c apacity

c) enthalpy

b) s pecific h eat

d) kinetic e nergy

3. Equal m asses o f t wo s ubstances, A & B , e ach a bsorb 2 5 J oules o f e nergy. I f t he t emperature o f A

increases b y 4 d egrees a nd t he t emperature o f B i ncreases b y 8 d egrees, o ne c an s ay t hat

a) t he s pecific h eat o f A i s d ouble t hat o f B .

b) t he s pecific h eat o f B i s d ouble t hat o f A .

c) the s pecific h eat o f B i s n egative.

d) t he s pecific h eat o f B i s t riple t hat o f A .

4. If 2 5 J a re r equired t o c hange t he t emperature o f 5 .0 g o f s ubstance A b y 2 .0°C, w hat i s t he s pecific

heat o f s ubstance A ?

a) 250 J /g°C

c) 10. J /g°C

b) 6 3 J /g°C

d) 2.5 J /g ° C

5. How m uch e nergy i s r equired t o c hange t he t emperature o f 2 .00 g a luminum f rom 2 0.0°C t o 2 5.0°C?

The s pecific h eat o f a luminum i s 0 .902 J /g°C.

a) 2.3 J

c) 0.36 J

b) 9 .0 J

d) 0.090 J

6. Consider t he t hermal e nergy t ransfer d uring a c hemical p rocess. W hen h eat i s t ransferred t o t he

system, t he p rocess i s s aid t o b e _ ______ a nd t he s ign o f Δ H i s _ _______.

a) exothermic, p ositive

c) exothermic, n egative

b) e ndothermic, n egative

d) e ndothermic, p ositive

Chapter 5: Thermodynamics Worksheet With Answers - Ap Chemistry 2015-2016 Page 10

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