p1.2.2 energy and temperature Flashcards
energy and temperature
what is temperature?
is a measure of the average kinetic energy of a substance particles, measured in degrees Celsius or kelvin
what is energy?
is the measure of the total thermal energy stored in an object measured in joules
what physical changes happen when a solid is heated?
particles gain more energy and they move more and their temperature increases
particles undergo a change of state e.g. melting or boiling
what chemical change happens when a solid is heated?
a reaction is triggered and different molecules are formed
what’s a physical change?
the change is reversible like changes of state e.g. filtering sand from water
what’s a chemical change?
the reaction is irreversible and a new substance is formed e.g. forming new salts
why is baking a cake a chemical reaction?
because you cannot change it to the way it was and the cake is now a new substance that has been foermed
why is melting chocolate a physical reaction?
because it can be returned to its former state by freezing and the particles undergoes a change of state e.g. melting
during a state change, what happens to the temperature of a substance?
it remains constant
why is energy being used in a state of change?
it is used to break (heating) or make (cooling) intermolecular bonds
cooling curve of steric acid
liquid
physical change
solid
what are factors that will affect the amount of heat required?
the type of material
the mass of material
the temperature
what is specific heat capacity?
the specific heat capacity of a material is the amount of heat required to raise the temperature of 1kg of a material by 1’c
what is the equation for change in thermal energy?
mass x specific heat capacity x temperature change
what is the equation for mass?
change in thermal energy / specific heat capacity x temperature change
