Question

50 Points- Chemistry

Some thermodynamic properties of ethanol are listed in the table.

Thermodynamic Properties

Property Value
c (solid) 0.5 J/g °C
c (liquid) 1.0 J/g °C
c (gas) 2.0 J/g °C
Melting Point −114 °C
Boiling Point 78 °C


How much heat is released when 50.0 g of ethanol cools from 90 °C to 79 °C?

1,200 J
1,100 J
600 J
550 J

Answer 1

1,100 J.

Step-by-step explanation:

Answer 2

1,100 J.

Step-by-step explanation:

• The amount of heat added to a substance (Q) can be calculated from the relation:

Q = m.c.ΔT.

where, Q is the amount of heat released from ethanol cooling,

m is the mass of ethanol (m = 50.0 g),

c is the specific heat of ethanol in the gas phase, since the T is cooled above the boiling point (c = 2.0 J/g °C),

ΔT is the temperature difference (final T - initial T) (ΔT = 79.0 °C – 90.0 °C = - 11.0 °C).

∴ Q = m.c.ΔT = (50.0 g)(2.0 J/g °C)(- 11.0 °C) = - 1100 J.

The system releases 1,100 J.