Answer: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
:
q
3
=
m
⋅
c
w
a
t
e
r
⋅
Δ
T
=
50.0
g
⋅
4.18
J
g
⋅
∘
C
⋅
(
100
∘
C
−
0
∘
C
)
=
20900
J
4. Determine the heat required to convert
100
∘
C
water to
100
∘
C
vapor:
q
4
=
m
⋅
Δ
H
v
=
50.0
g
⋅
2257
J
g
=
112850
J
5. Determine the heat required to go from
100
∘
C
vapor to
120
∘
C
vapor:
q
5
=
m
⋅
c
v
a
p
o
r
⋅
Δ
T
=
50.0
g
⋅
2.09
J
g
⋅
∘
C
⋅
(
120
∘
C
−
100
∘
C
)
=
2090
J
Therefore, the total heat required is
q
T
O
T
A
L
=
q
1
+
q
2
+
q
3
+
q
4
+
q
5
=
152696.5
J
=
153.7
k
J
Step-by-step explanation: