Monday 7 Dec

Monday 8 Dec:

Target: Understanding Temp & Heat

Quiz: Both Free Response Q's

CH #13:

1. What are the three ways that heat (Q) is transferred:

Conduction: Physical contact

Convection: Density currents, hotter material rises/cooler settles

Radiation: IR radiation (EM Waves)

2. Explain thermal equilibrium.

Two substances that are placed in intimate contact will reach thermal equilibrium through a process where the higher temperature substance(s) will always and continually to give energy (HEAT) to the cooler substance until both have the same temperature (the phase has no bearing, only temperature of the two substances). But the rate of transfer of heat will depend on the temperature difference and the specific heat of each substance. (As a system, Heat always flows from hot to cold!!!)

3. Explain Specific Heat (c).

Ability of a substance to “hold” (not to change temperature) heat (Q). Large specific heat means that it takes longer (gives/takes more Joules of energy à Q) for a substance to change its temperature compared to other substances. Water’s specific is extremely high and metals/ground is low. Q = m(DT) c (where c is specific heat) for any substance within one phase.

4. Explain heat transfer (Q) during a phase change

Heat of Fusion (L_F :between solid and liquid) and Heat of Vaporization (L_V :between liquid and vapor/gas).

Q = m(L_Vor L_F):

· Note: no DT during a phase change.

· Note: More energy is required during a phase change than in heating within a phase.

New Material (Ch 14)

1. Change of p (and T) at constant volume; an isovolumetric change.

2. Change of V (and T) at constant pressure; an isobaric change.

3. Change in p and V at constant temperature; an isothermal change.

4. Change in p and V in an insulated container (no heating of the gas); an adiabatic change. On a p-V diagram, an isothermal looks pretty much like an adiabatic. However, if an isothermal and an adiabatic have a point in common, then the adiabatic is the curve having the greater slope at that point.

2. Explain & show on a diagram (PV diagram): Isovolumetric, Isobaric, Isothermal, Adiabatic:

· An isovolumetric/isochoric process, (constant volume).

· An isobaric process occurs at constant pressure.

The yellow area represents the work

An isothermal process occurs at a constant temperature (shallow slope).

The yellow area represents "work" for this isothermal change

· An adiabatic process occurs without loss or gain of heat (steeper slope) (very fast cycleà Carnot cycle/auto engines).

For a simple substance, during an adiabatic process in which the volume increases, the internal energy of the working substance must necessarily decrease

Heat is transferred to the gas during 1-2 (Q_H) and heat is given off (taken from) during 3-4 (Q_L).

a. Undergoes isothermal expansion in 1 à 2 while absorbing heat from high temperature reservoir

b. Undergoes adiabatic expansion in 2 à 3

c. Undergoes isothermal compression in 3 à 4, and

d. Undergoes adiabatic compression in 4 à 1.

Finish & Correct Free Response



	Monday 8 Dec: Target: Understanding Temp & Heat Quiz: Both Free Response Q's CH #13: 1. What are the three ways that heat (Q) is transferred: Conduction: Physical contact Convection: Density currents, hotter material rises/cooler settles Radiation: IR radiation (EM Waves) 2. Explain thermal equilibrium. Two substances that are placed in intimate contact will reach thermal equilibrium through a process where the higher temperature substance(s) will always and continually to give energy (HEAT) to the cooler substance until both have the same temperature (the phase has no bearing, only temperature of the two substances). But the rate of transfer of heat will depend on the temperature difference and the specific heat of each substance. (As a system, Heat always flows from hot to cold!!!) 3. Explain Specific Heat (c). Ability of a substance to “hold” (not to change temperature) heat (Q). Large specific heat means that it takes longer (gives/takes more Joules of energy à Q) for a substance to change its temperature compared to other substances. Water’s specific is extremely high and metals/ground is low. Q = m(DT) c (where c is specific heat) for any substance within one phase. 4. Explain heat transfer (Q) during a phase change Heat of Fusion (L_F :between solid and liquid) and Heat of Vaporization (L_V :between liquid and vapor/gas). Q = m(L_Vor L_F): · Note: no DT during a phase change. · Note: More energy is required during a phase change than in heating within a phase. New Material (Ch 14) 1. Change of p (and T) at constant volume; an isovolumetric change. 2. Change of V (and T) at constant pressure; an isobaric change. 3. Change in p and V at constant temperature; an isothermal change. 4. Change in p and V in an insulated container (no heating of the gas); an adiabatic change. On a p-V diagram, an isothermal looks pretty much like an adiabatic. However, if an isothermal and an adiabatic have a point in common, then the adiabatic is the curve having the greater slope at that point. 2. Explain & show on a diagram (PV diagram): Isovolumetric, Isobaric, Isothermal, Adiabatic: · An isovolumetric/isochoric process, (constant volume). · An isobaric process occurs at constant pressure. The yellow area represents the work An isothermal process occurs at a constant temperature (shallow slope). The yellow area represents "work" for this isothermal change · An adiabatic process occurs without loss or gain of heat (steeper slope) (very fast cycleà Carnot cycle/auto engines). For a simple substance, during an adiabatic process in which the volume increases, the internal energy of the working substance must necessarily decrease Heat is transferred to the gas during 1-2 (Q_H) and heat is given off (taken from) during 3-4 (Q_L). a. Undergoes isothermal expansion in 1 à 2 while absorbing heat from high temperature reservoir b. Undergoes adiabatic expansion in 2 à 3 c. Undergoes isothermal compression in 3 à 4, and d. Undergoes adiabatic compression in 4 à 1. Finish & Correct Free Response