Chapter 4. Heat and Temperature. Matter. All matter is made up of tiny, basic units called atoms. Atoms cannot be created, destroyed, or divided during chemical or physical changes.
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Heat and Temperature
A Solid-Vibration only
B Liquid-Vibration and Rotation only
C Gas-Vibration, Rotation and Translation
Celsius or Centigrade(oC)
Kelvin (Absolute Temperature)(K)
oF = (oC x 1.8) + 32
oF = (34oC x 1.8) + 32 = 93oF
oC = (oF – 32)
oC = (-22.7oF – 32) = -30.4oC
K = oC + 273
K = -30.4oC + 273 = 242.6 K
The liter of water contains more internal energy. It would require more ice
cubes to cool it.
Q = heat
m = mass
c = specific heat
ΔT = Change in Temperature
c, specific heat, is a physical property associated with
every substance. It depends on the internal structure of the substance (the atoms and molecules)
The value for c indicates how much heat is required to raise the temperature of 1 g of a substance by 1oC.
The units for specific heat are cal/goC or J/goC
The specific heat for water (c water) is 1 cal/goC
Q = ?Q = c x m x ΔT
C= 2.7 cal/goCQ = 57.3 g x 2.7 cal/goC x 5.7 oC
ΔT = 5.7 oCQ = 881.8 cal
m = 57.3 g
Q=5000 cal Q = m x c x ΔT
m = 100 g ΔT = Q
m x c
T1 = 20°C
ΔT = 5000 cal
100 g x 1 cal/goC
T2 = ?
C = 1 cal/g°C
ΔT = 50 oC
ΔT = T2 – T1
T2 = ΔT+ T1
T2=50 oC + 20°C
In coastal areas temperature vary less than inland.
Because water has a higher specific heat than land,
it ends up absorbing much of the atmospheric heat,
which helps keep temperatures cooler. Water releases heat gradually
when the atmosphere is cold, which keeps temperatures warmer.
Energy to turn water from a liquid to
a gas or vice versa!
Energy to turn water from a solid to a liquid or vice versa!
Lv is the latent heat of vaporization, per gram of the substance.
Lf is the latent heat of fusion, per gram of the substance.
After evaporation occurs the remaining substance is at a cooler
temperature. This is until the substance is again warmed by the
atmosphere and the process repeats.
Perspiration in humans is a cooling process.
Energy can neither be created nor destroyed. It can only be changed from one form to another.
Heat: Lost energy
Matter, atoms, molecules, elements, compounds.
Temperature-What is it (A measure of the amount of heat a body contains)
Relationship among temperature, heat, kinetic energy (The higher the temperature the higher the heat content and the kinetic energy content)
Types of movement in solids, liquids and gases. (Translation, vibration and rotation in gases; only vibration and rotation in liquids and solids).
Temperature scales.(oF, oC, K)
Freezing and boiling points of water
Internal (atoms and molecules) and External Energy (normal size particles)
Specific heat-Amount of energy in calories or joules needed to increase the temperature of 1 g of a substance by 1oC.
Calorie & Kilocalorie
1 cal = 4.184 J
Q = m x c x ΔT
Specific heat of water (1 cal/goC)
Phase changes-freezing and melting (s-l); condensation and vaporization (l-g); deposition and sublimation (s-g).
s-l, l-g, and s-g are endothermic. l-s, g-l, and g-s are exothermic. The temperature remains constant during all phase changes.
fp and mp; cp and bp; dp and sp.
Fusion is the same as melting.
Vaporization includes evaporation (below the boiling point) and boiling.
Latent heat of vaporization and fusion (Amount of energy needed to convert a liquid to a gas and a solid to a liquid).
Diagrams for phase changes
Evaporation-Molecules at the surface with enough kinetic energy escape to the vapor state.
Laws of Thermodynamics:
1o Law-Energy cannot be created or destroyed. Energy added is converted to work + internal energy.
2o Law-Heat is transferred from a warmer object to a colder object. The entropy of the universe is always increasing.
3o Law-All movement stops at 0K (Absolute 0).
Entropy-State of disorder.