Energy- the ability to do work.

ex , Potential, thermal, kinetic, electrical, mechanical, sound, chemical, gravitational
nuclear, light, and etc

ΔE=q+W <== W= -pΔV
...but ΔV is usually minuscule, so typically,
ΔE = q

Energy Units

1 Joule = 1 kgm^2/s^21 calorie = 1 cal = 4.184 J1 Calorie = 1000 cal = 1 kcal = 4184 J = 4.184 kJ

Specific Heat Capacity (C or J/g*C or J/g*K) - the energy required to raise the temperature of 1 gram of a substance 1 degree Celsius

• higher heat capacity requires more energy to raise the temperature, "temperature inertia"
• highest to lowest specific heat: water (4.184 J/g*K), glass (.8 J/g*K), steel/iron (.449 J/g*K)
• example of water's high specific heat capacity: in summer, Lake Michigan is absorbing the heat and cooling down Chicago and in winter the lake releases the stored energy to warm up the city.

Heat Transfer - occurs when two objects of different temperatures are brought into contact

**** Always occurs from HIGH temperature to LOW temperature
** Occurs until both objects are at same temperature >>> THERMAL EQUILIBRIUM!

Two types of Heat Transfer:

Endothermic - heat transferred from surroundings to system (IN)

Exothermic- heat transferred from system to surroundings ( OUT )


Sign Conventions

Temperature change of system	Sign of temperature change	Sign of Heat (Q)	Direction of Heat Transfer
INCREASE	+	+	Endothermic
DECREASE	-	-	Exothermic

system = the "area" being studied
surroundings = everything else
temperature = a measure of the average kinetic energy of the particles
heat = sum of all energies in a substance (kinetic is one of them); dependent on the amount of substance
First Law of Thermodynamics- total energy is constant in the universe, defined as system plus surroundings
energy- transfer between system and surroundings as Heat or Work takes place

Temperature Change Calculation
q = mcΔt
energy = (mass)(specific heat)(change in temperature or final temp. - initial temp.)

State Change Calculation
q = mΔH
energy = (mass)(heat of fusion/vaporization)

Elements have no formation reactions so you can ignore them.


#s of some common elements/compounds

heat capacity (J/g°C)

heat of fusion (J/g)

heat of vaporization (J/g)

melting point (°C)

boiling point (°C)

	solid	liquid	gas
aluminum (Al)	0.91	1.05	0.798	402	10540	660	2450
copper (Cu)	0.385	0.42	0.33	205	4812	1083	2582
gold (Au)	0.128	0.14	0.105	64.4	1736	1063	2660
magnesium (Mg)	0.983	1.21	0.853	372	5607	650	1117
sodium (Na)	1.23	1.39	0.904	113	4393	98	889
potassium (K)	0.745	0.75	0.531	63	2020	63	757
mercury (Hg)	0.14	0.139	0.105	11.6	290	-39	357
bromine (Br)	0.338	0.462	0.225	66.1	187	7	59
iodine (I)	0.217	0.32	0.146	61.7	172	114	184
hydrogen (H)	2.38	0.967	14.3	59	448	-259	-253
oxygen (O)	1.41	1.65	0.916	14	213	-219	-183
water (H20)	2.1	4.184	1.7	335	2260	0	100

Calorimetry: Measuring heat transferred by chemical or physical properties

“Coffee Cup” Calorimetry:
heat gained = - heat lost
q system + q surroundings = 0

Bomb Calorimetry:
q bomb + q system + q surroundings = 0

• the specific heat of the bomb is a given number. the q of the bomb is the mass of the bomb times the c of the bomb.
• Usually, the q of the bomb and the q of the surroundings are together because the heat lost by the system is gained by both the bomb and the surroundings.