JMJ
8-1 Heat and Heat Transfer
Theme: Systems
Great link for this topic http://www.middleschoolchemistry.com/multimedia/chapter1/lesson1
(All the lessons in Chapter 1 are helpful)
Four States of Matter
Name
Describe
Describe using kinetic theory
Thermal expansion – define, recognize examples
Changes of State
Interpret changes of state in terms of kinetic theory of matter
Names for all state transitions
Boiling point/Condensing point
Melting point/Freezing point
Read and interpret a change of state graph
Boiling point elevation
Freezing point depression
Thermal energy
Definition
Heat
Movement of heat
Temperature
Making and calibrating thermometers
Temperature Scales – similarities and differences
Fahrenheit
Celsius
Kelvin
Absolute zero
Law of Conservation of Energy
Specific Heat Capacity
Definition
Specific heat capacity =
𝐻𝑒𝑎𝑡 𝑔𝑎𝑖𝑛𝑒𝑑 (𝐽)
𝑀𝑎𝑠𝑠 (𝑔)𝑥 𝐶ℎ𝑎𝑛𝑔𝑒 𝑖𝑛 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 (℃)
Objects with low specific heat capacities heat up more quickly than objects with high
specific heat capacities.
Heat conductors and insulators
Calorimeter – what is it used for, how is a coffee cup calorimeter made?
Using a calorimeter to calculate specific heat capacity
Law of Conservation of Energy applies
Energy transferred to the water is equal to the energy transferred from the object
Calculations:
Known: Specific heat capacity of water = 4.184 J/g °C
Energy transferred to water = mass of water (g) x Temp change (°C) x 4.184 J/g °C
Specific heat capacity of object =
Summary:
Heat is the transfer of thermal energy, which includes the total energy of the particles of a
substance - both kinetic and potential energy. Temperature is a measure of the average kinetic
energy of a substance or in an environment. When heat is transferred from areas of higher to
lower heat, kinetic energy is transferred from areas of higher to lower kinetic energy (higher to
lower temperature). The result is an increase in temperature in the area that once had the lower
kinetic energy and a decrease in temperature in the area that once had the higher kinetic energy.
The transfer of heat is balanced (in equilibrium) when the kinetic energy (temperature) of both
areas is equivalent.
In general, matter expands when heated and contracts when cooled because of changes in
the kinetic energy of molecules. Changes in heat can also result in changes in the state or phase
of matter because of changes in kinetic and potential energy of molecules.
The boiling point of water represents the transfer of enough thermal energy to increase
the kinetic energy of molecules and break the attractive forces between molecules so that water
changes from a liquid to a gas. The freezing point of water represents the transfer of thermal
energy such that the kinetic energy of molecules and the formation of attractive forces between
molecules result in the change of liquid water to solid ice.
Adding a solute to water decreases the freezing point of water and increases its boiling
point.
This Investigation involved calculating a property of matter called specific heat capacity.
Specific heat capacity is a measure of the amount of heat energy (Joules) required to raise the
temperature of 1 gram of a substance 1 degree Celsius. Different substances require different
amounts of energy in order to raise their temperature by 1 degree Celsius, hence they absorb heat
energy at different rates. The experiment required the creation of a calorimeter, a piece of
equipment designed to prevent heat loss from or gain to the substances contained within it.
Styrofoam cups were chosen since Styrofoam does not absorb heat energy from the water
contained within it, thereby allowing the initial and final temperatures of water to reflect heat lost
from the solid substance alone. Two metals, steel and lead, were tested. The equation for
specific heat capacity was applied and it was determined that steel had a higher specific heat
capacity than lead.
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