Chapter 10 Worksheet #2 Answer

[Pages:2]Name ________KEY__________ Block _______

Chapter 10 Worksheet #2

1. Calculate the energy require (in calories) to heat 10.4 g of mercury from 37.0oC to 42.0oC. Specific heat of mercury is 0.14 J/goC.

q = m c t q =10.4 g ? 0.14 J/goC ? 5.00 oC =

7.28 J ? 1 cal 4.184 J

= 1.74 cal

2. If 50. J of heat are applied to 10. g of iron, by how much will the temperature of the iron increase? The specific heat of iron is 0.45 J/goC.

t = q / m c t =50. J / 10.g ? 0.45 J/goC =

50 J goC 10.g ? 0.45 J

= 11 oC

3. Calculate the amount of energy required (in calories) to heat 145 g of water from 22.3oC to 75.0oC.

q = m c t q =145 g ? 1.00 J/goC ? (75 oC -22.3 oC) = 145 g ? 1.00 J/goC ? 52.7 oC

7641.5 cal = 7640 cal

4. If 52.5 kJ of heat is heated to a 1.02 kg block of metal, the temperature of the metal increases by 11.2oC. Calculate the specific heat capacity of the metal in J/goC. c = q / m t convert units 52.5 KJ = 52,500 J and 1.02 kg = 1,020 g c =52,500 J / 1,020.g ? 11.2 oC c = 4.595588 J/goC = 4.60 J/goC

5. If 4.524 x 103 J of heat is applied to a 742.1 g sample of iron, by how many degrees Celsius will the temperature of the iron sample increase? Specific heat is 0.45 J/goC.

t = q / m c q =4.524 x 103 J / 742.1 g ? 0.45 J/goC =

4.524 x 103 J goC = 0.013547141oC = 0.01355 oC or 1.355 x 102 oC 742.1.g ? 0.45 J

6. What was the initial temperature of a 32.5 g iron bar if 276.8 J of energy were applied resulting in a final temperature of 95.4oC? The specific heat capacity of solid iron is 0.45 J/goC.

t = q / m c t =276.8 J / 32.5 g ? 0.45 J/goC =

276.8 J goC

= 18.9 oC

32.5.g ? 0.45 J 95.4 oC -- 18.9 oC =76.5 oC

7. Are the following processes exothermic or endothermic?

a. the combustion of gasoline in a car engine

Exothermic

b. water condensing on a cold pipe

Endothermic

c. CO2 (s)

CO2 (g)

Endothermic

d. F2 (g) 2 F (g)

Exothermic

8. Why does ice float on the surface of liquid water? It is less dense then water (the Crystallized structure).

9. Perform the following conversions. a. 850 cal to J

3556.4 J

850 cal x 4.184 J = 3556.4 J 1 cal

b. 5.901 J to cal

1.421 cal

5.901 J x 1 cal = 1.421 cal 4.184 J

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