Chemistry

Name: _____________________________ THERMOCHEMISTRY WORKSHEET #4

1.

Draw and label a cooling curve and describe the changes occurring at the atomic level when a o o sample of cesium gas at 800 C is cooled to a solid at 0.0 C. Assume it passes through 2 phase o o changes. (m.p. = 28.4 C and the b.p. = 669 C).

2.

Ammonia has a melting point of –78 C and a boiling point of –33 C. Draw and label a heating curve and describe the changes occurring on a molecular level when a sample is heated from – o o 100.0 C to 0.0 C.

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Chemistry 3.

Name: _____________________________

Classify each change as either endothermic or exothermic and describe the form(s) of the transferred energy. o

a)

Aluminum metal is melted at 660 C.

b)

Krypton gas condenses at –152 C.

c)

Liquid Titanium metal at 1700 C and standard pressure is cooled to 25 C. The m.p. of o titanium = 1660 C

d)

Nickel at 25 C is drawn into a wire that reaches a temperature of 32 C. o The m.p. = 1453 C

e)

Ice sublimates –5.6 C from a solid to a gas.

f)

Sodium condenses at 883 C.

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