mcdeltaT notes.notebook

mcdeltaT notes.notebook
February 03, 2017
Calculating Thermal Energy
Q = m c Δ T
x
x
Calculating Thermal Energy
Q = m c Δ T
x
x
Energy = mass x specific heat x change in temp
J = (g) J (oC)
goC
1
mcdeltaT notes.notebook
February 03, 2017
Specific heat (capacity) = c =
amount of energy needed
to raise 1 gram of a
substance by 1oC
2
mcdeltaT notes.notebook
February 03, 2017
1) How much energy is required to
heat 355g of water from 20.0o C to
100.0o C?
1) How much energy is required to heat 355 g of water from 20.0o C to 100.0o C?
Q = (355g)(4.18J/goC)(80.0oC)
Q = 118712 J ~ 119,000 J
3
mcdeltaT notes.notebook
February 03, 2017
Source: www.periodictable.com
2) A 1.6 g sample of a grey metal
requires 5.8 J of energy to change its temperature from 23oC to 41oC.
Is the metal pure lead?
2) A 1.6 g sample of a grey metal requires 5.8 J of energy to change its temperature from 23oC to 41oC. Is the metal pure lead?
5.8 J = (1.6 g)(c)(18oC)
5.8 J = c
(1.6)(18oC)
0.20 J/goC = c
Check the specific heat chart...pure lead has a specific head capacity of 0.13 J/goC. Therefore not pure lead.
4
mcdeltaT notes.notebook
February 03, 2017
3) If 3.5kJ of energy are added to a 28.2g
sample of iron at 20oC, what is the final
temperature of the metal?
Source: www.periodictable.com
3) If 3.5kJ of energy are added to a 28.2g sample of iron at 20oC, what is the final temperature of the metal?
3500J = (28.2g)(0.45J/goC)(Δ T)
3500
= Δ T = 275.8 = 280oC
(28.2)(0.45)
final temp = 20oC+280oC = 300oC 5

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