What happens when we add energy to a solid at constant pressure gas.
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What happens when we add energy to a solid at constant pressure gas
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Transcript of What happens when we add energy to a solid at constant pressure gas.
What happens when we add energy to a solidat constant pressure
gas
What are the energy changes that occur?
H = Hfus x # mols
= m x Csolid x t
= m x Cliquid x t
H = Hvap x # mols
= m x Cgas x t
What would these changes look likeon a temperature versus energy graph?
H = Hfus x # mols
= m x Csolid x t
= m x Cliquid x t
H = Hvap x # mols
= m x Cgas x t
Heating curves and H
tem
pera
ture
added energy
Heating curves and H
tem
pera
ture
added energy
solid
liquid
gas
Heating curves and H
tem
pera
ture
added energy
melting/freezing pt
solid
liquid
gas
Heating curves and H
tem
pera
ture
added energy
melting/freezing pt
boiling/cond. pt
solid
liquid
gas
Heating curves and H
tem
pera
ture
added energy
melting/freezing pt
boiling/cond. pt
solid
liquid
gas
melting/freezingoccurring here
boiling/condensingoccurring here
How is the total enthalpy change (H) calculated for a substance whose temperature change
includes a change in state?
tem
pera
ture
added energy
t of solidabsorbing energy
tem
pera
ture
added energy
= m x Csolid x t
tem
pera
ture
added energy
= m x Csolid x t
the energy absorbedas a solid melts becomespotential energy, so no t
tem
pera
ture
added energy
H = Hfus x # mols
= m x Csolid x t
tem
pera
ture
added energy
H = Hfus x # mols t of liquidabsorbing energy
= m x Csolid x t
tem
pera
ture
added energy
H = Hfus x # mols = m x Cliquid x t
= m x Csolid x t
tem
pera
ture
added energy
H = Hfus x # mols
the energy absorbedas a liquid boils becomes
potential energy, so no t
= m x Cliquid x t
= m x Csolid x t
tem
pera
ture
added energy
H = Hfus x # mols
H = Hvap x # mols
= m x Cliquid x t
= m x Csolid x t
tem
pera
ture
added energy
H = Hfus x # mols
H = Hvap x # mols
t of gasabsorbing energy
= m x Cliquid x t
= m x Csolid x t
tem
pera
ture
added energy
H = Hfus x # mols
H = Hvap x # mols
= m x Cgas x t
= m x Cliquid x t
= m x Csolid x t
tem
pera
ture
added energy
H = Hfus x # mols
H = Hvap x # mols
= m x Cgas x t
= m x Cliquid x t
= m x Csolid x t
tem
pera
ture
added energy
H = Hfus x # mols
H = Hvap x # mols
= m x Cgas x t
= m x Cliquid x t
= m x Csolid x t
The H of any substancebeing heated will be the sum of theH of any t occurring plus H of any phase change occurring
tem
pera
ture
added energy
= Hfus x # mols
= Hvap x # mols
= m x Cgas x t
= m x Cliquid x t
= m x Csolid x t
The H of any substancebeing heated will be the sum of theH of any t occurring plus H of any phase change occurring
tem
pera
ture
added energy
H = Hfus x # mols
H = Hvap x # mols
= m x Cgas x t
= m x Cliquid x t
= m x Csolid x t
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?
tem
pera
ture
added energy
-20 oC
0 oC
50 oC
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?
tem
pera
ture
added energy
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?
-20 oC
0 oC
50 oC
use the following values:Cice = 2.1 J/goc, Hfus H2O = 6.01 kJ/mol, CH2O liq = 4.186 J/goC
tem
pera
ture
added energy
-20 oC
0 oC
50 oC
H = Hfus x # mols = m x Cliquid x t
= m x Csolid x t
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?use the following values:Cice = 2.1 J/goc, Hfus H2O = 6.01 kJ/mol, CH2O liq = 4.186 J/goC
tem
pera
ture
added energy
-20 oC
0 oC
50 oC
H = Hfus x # mols
= 10g x 2.1 J/goC x 20oC
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?use the following values:Cice = 2.1 J/goc, Hfus H2O = 6.01 kJ/mol, CH2O liq = 4.186 J/goC
= m x Cliquid x t
tem
pera
ture
added energy
-20 oC
0 oC
50 oC
= 10g x 2.1 J/goC x 20oC
H2=10 g x 1mol/18g x 6.01 kJ/mol
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?use the following values:Cice = 2.1 J/goc, Hfus H2O = 6.01 kJ/mol, CH2O liq = 4.186 J/goC
= m x Cliquid x t
tem
pera
ture
added energy
-20 oC
0 oC
50 oC
= 10g x 4.186 J/goC x 50 oC
= 10g x 2.1 J/goC x 20oC
H2=10 g x 1mol/18g x 6.01 kJ/mol
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?use the following values:Cice = 2.1 J/goc, Hfus H2O = 6.01 kJ/mol, CH2O liq = 4.186 J/goC
tem
pera
ture
added energy
-20 oC
0 oC
50 oC = 10g x 4.186 J/goC x 50 oC
= 10g x 2.1 J/goC x 20oC
H2=10 g x 1mol/18g x 6.01 kJ/mol
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?use the following values:Cice = 2.1 J/goc, Hfus H2O = 6.01 kJ/mol, CH2O liq = 4.186 J/goC
total H = + H2 +
tem
pera
ture
added energy
-20 oC
0 oC
50 oC
= 10g x 2.1 J/goC x 20oC
H2=10 g x 1mol/18g x 6.01 kJ/mol
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?use the following values:Cice = 2.1 J/goc, Hfus H2O = 6.01 kJ/mol, CH2O liq = 4.186 J/goC
total H = + H2 +
= 420 J + 3340 J + 2093 J = 10g x 4.186 J/goC x 50 oC
tem
pera
ture
added energy
-20 oC
0 oC
50 oC
= 10g x 2.1 J/goC x 20oC
H2=10 g x 1mol/18g x 6.01 kJ/mol
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?use the following values:Cice = 2.1 J/goc, Hfus H2O = 6.01 kJ/mol, CH2O liq = 4.186 J/goC
total H = + H2 +
5853 J = 420 J + 3340 J + 2093 J = 10g x 4.186 J/goC x 50 oC
tem
pera
ture
added energy
-20 oC
0 oC
50 oC
= 10g x 2.1 J/goC x 20 oC
H2=10 g x 1mol/18g x 6.01 kJ/mol
EXAMPLE: What is H for 10 g water with a total t from -20 oC to +50 oC?
It takes 5853 joules to heat up 10 gramsof water from -20 oC to +50 oC.
= 10g x 4.186 J/goC x 50 oC
mice
18X Hfus
Heat lost by ice
= mw X Cp X T
Heat gained by water
Example II:
Ice at 0oC is placed in a Styrofoam cup containing 0.32 kg of lemonade at 27oC. The specific heat capacity of lemonade is virtually the same as that of water. After the ice and lemonade reach an equilibrium temperature, some ice still remains. Assume that the cup absorbs a negligible amount of heat.
miceg X 1mol/18g X 6010J/mole = 320g X 4.18J/g.Co X (27oC -0oC)
mice = 108.1g
