Question

What is the change in energy (inkJ) when 15.0 g of water 85.0 degrees * C is converted to ice at C?

Answer 1

Explanation:

The answer is

153.7

k

J

.

What you are asked to determine is the total energy required to go from ice to water, and then from water to vapor - the phase changes underwent by the water molecules.

In order to do this, you'll need to know:

Heat of fusion of water:

Δ

H

f

=

334

J

/

g

;

Heat of fusion vaporization of water:

Δ

H

v

=

2257

J

/

g

;

Specific heat of ice:

c

=

2.09

J

/

g

∘

C

;

Specific heat of water:

c

=

4.18

J

/

g

∘

C

;

Specific heat of steam:

c

=

2.09

J

/

g

∘

C

;

So, the following steps describe the overall process:

1. Determine the heat required to raise the temperature of the ice from

−

15.0

∘

C

to

0

∘

C

:

q

1

=

m

⋅

c

i

c

e

⋅

Δ

T

=

50.0

g

⋅

2.09

J

g

⋅

∘

C

⋅

(

0

∘

C

−

(

−

15

∘

C

)

)

=

1567.5

J

2. Determine the heat required to convert

0

∘

C

ice to

0

∘

C

water:

q

2

=

m

⋅

Δ

H

f

=

50.0

g

⋅

334

J

g

=

16700

J

3. Determine the heat required to go from water at

0

∘

C

to water at

100

∘

C

: