How much heat is given off when a 24.7 kg iron ingot is cooled from 880°C to 13°C?
Answers
Answer:
Explanation:
Answer:
2.3
⋅
10
6
cal
Explanation:
Notice that the problem provides you with the mass of the iron ingot, but that it's being expressed in kilograms.
Since the specific heat of iron is given in joules per gram Celsius,
J g
−
1
∘
C
−
1
, you must convert the mass of the sample from kilograms to grams before doing anything else
24.7
kg
⋅
10
3
g
1
kg
=
24.7
⋅
10
3
g
Now, you can use the specific heat of iron to figure out how much heat would be released when the temperature of
24.7
⋅
10
3
g
of iron decreases by
1
∘
C
24.7
⋅
10
3
g
⋅
the specific heat of iron
0.107 cal
1
g
∘
C
=
2.643
⋅
10
3
cal
∘
C
−
1
This tells you that in order to cause a
1
∘
C
decrease in temperature to a
24.7
⋅
10
3
g
sample of iron, you must remove
2.643
⋅
10
3
cal
of heat.
In your case, the temperature of the ingot must decrease by
change in temperature
=
|
13
∘
C
−
880
∘
C
|
=
867
∘
C
You can thus say that when the temperature of
2.643
⋅
10
3
g
of iron decreases by
867
∘
C
, the process releases
867
∘
C
⋅
for 2.643
⋅
10
3
g of iron
2.643
⋅
10
3
cal
1
∘
C
=
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
∣
∣
a
a
2.3
⋅
10
6
cal
−−−−−−−−−−−−−−
this which are written in downward , that you write in a line like
10
6
=10^6