Molar mass allows us to convert from molar heat capacity to specific heat
Water has a molar heat capacity of 75.3 J/(molC). Find its specific heat
capacity in cal/(g C).
1 mol H2O
Suppose you eat
Which will have the greatest reaction rate and why?
A Catalyst generally speeds up a reaction.
The Catalytic converter in your car speeds up the decomposition of Harmful
NO,NO2, N2O4 into N2 and O2. In general a catalyst holds a molecule in the
Hess Law Example 2 (optional)
Calculate the enthalpy of formation of carbon dioxide from its elements:
C(g) + 2O CO2 (g)
Use the following equations:
H = -250 kJ
H = +720 kJ
CO2 (g) C(s) + O2
H = +390 kJ
Answer-Give it some think time
The Activation Energy represents an Energy Barrier to formation of the
products. Some form of energy must be present to supply this energy in order
for a reaction to occur. It can be a small or a large amount, depending on the
size of th
Germain Henri Hess (1802 - 1850) is important primarily for his
thermochemical studies, which began in 1839; his other work was of less
importance. The key paper was published in 1840. The contributions of Hess
to heat can be summed up in what i
For Exothermic reactions:
A + 2B D + 250 J
A + 2B D
H = -250J
For Endothermic Reactions
D + 250 J A + 2B
A + 2B
H = 250J
Heat in a Reaction
C3.1d Calculate the amount of heat produced for a given mass of reactant
from a balanced reaction.
is the study of heat transfer from 1 object to another.
Heat Transfer happens during phase changes and chemical reactions.
This is energy due to motion
British Thermal Units
(A non-metric unit of heat
used in USA)
calories heat needed to raise
1 gram of water by 1
Calories 1 Food Calorie = 1000 calories, 1 Calorie will raise 1000 g of water
by 1 C
Metric unit of heat.
C3.1d Calculate dH for a chemical reaction using a simple coffee calorimeter.
Specific Heat Capacity Cp describes how much heat is needed to change
the temperature of 1 gram something
Water is 4.184 J/(gC) or 1.000 cal /(g C)