AQA GCSE COMBINED SCIENCE
TRILOGY HIGHER TIER CHEMISTRY
PAPER 1H 5
◉ Energy is transferred.... Answer: Mechanically (by a force doing
work), electrically (work done by moving charges), by heating or by
radiation (like light or sound)
◉ When a system changes, energy is transferred. Answer: It can be
transferred into or away from the system, between objects in the
system or between different types of energy stores. Closed systems
are where neither matter nor energy can enter or leave. The net
change in the total energy of a closed system is always 0
◉ kinetic energy. Answer: energy of motion - the greater an object's
mass and the faster it is going, the more energy there will be in its
kinetic energy store. Ek (j) = 1/2m(kg)v(m/s) squared
◉ Raised objects store energy in gravitational potential energy
stores. Answer: lifting an object in a gravitational field requires
work, causing an energy transfer to the the GPE store of the object.
Ep(j) = m(kg)g(n/kg)h(m)
,◉ Falling objects transfer energy. Answer: Falling objects transfer
energy from its GPE store to its kinetic energy store. When there's
no air resistance, energy lost from the GPE store = energy gained in
the kinetic energy store
◉ Stretching transfers energy to elastic potential energy stores.
Answer: As long as the limit of proportionality has not been
exceeded, Ee (j) = 1/2 k (N/m) e (m) squared
◉ specific heat capacity. Answer: the energy required to raise the
temperature of one gram of a substance by one degree Celsius. E
(j) = m(kg) c(j/kgdegree) theta (degrees Celsius)
◉ Conservation of energy principle. Answer: Energy can be
transferred but can never be created of destroyed
◉ Dissipated energy. Answer: energy used up in a system, typically
lost due to work done by friction, 'wasted energy'
◉ Phone energy. Answer: When you use the phone, energy is
usefully transferred from the chemical energy store of the battery in
the phone, but some of this energy is dissipated to thermal energy
◉ Closed system energy transfer. Answer: A cold spoon is dropped
into hot soup in an insulated flask, which is then sealed. Energy is
,transferred from the thermal energy store of the soup to the useless
thermal energy of the spoon
◉ Power. Answer: The rate at which work is done (watts). P(w) =
E(j) / t(s)
◉ Powerful machine. Answer: One which transfers a lot of energy in
a short space of time
◉ Conduction occurs mainly in solids. Answer: Conduction is the
process where vibrating particles transfer energy to neighbouring
particles.
◉ Long definition of conduction. Answer: Energy transferred to an
object by heating is transferred to the thermal store, which is shared
across the kinetic store of the particles. The particles' collisions
cause energy to be transferred between particles kinetic energy
stores.
◉ thermal conductivity. Answer: the Mrs sure of the rate at which
thermal energy can travel through a material
◉ Convection occurs only in liquids and gases. Answer: Convection
is where energetic particles move away from hotter to cooler regions
, ◉ Convection longer definition. Answer: Unlike in solids, the
particles in liquids and gases are able to move. When you heat a
region of a gas/liquid, the particles move faster and the space
between particles increases. This causes the density of the region to
decrease. Because they can flow, the warmer and less dense region
will rise above denser cooler regions. If there is a constant heat
source, a convection current will be made
◉ Radiators - convection currents. Answer: Energy is transferred
from the radiator to nearby air particles by conduction. The air by
the radiator becomes warmer and less dense. This warm air rises
and is replaced by cooler air. At the same time, the previously heated
air transfers energy to the surrounding and cools, becomes denser,
and sinks. This cycle repeats and causes a flow of air to circulate
around the room
◉ How to reduce unwanted energy transfers. Answer: Lubrication
and thermal insulation
◉ Lubrication reduces frictional forces. Answer: When something
moves, there's at least one frictional force acting on it, causing some
energy to be dissipated. For objects that are rubbed together,
lubricants reduce the fiction between the object's surfaces when
moved. Lubricants tend to be liquids (like oil) to flow easily between
objects and coat them
TRILOGY HIGHER TIER CHEMISTRY
PAPER 1H 5
◉ Energy is transferred.... Answer: Mechanically (by a force doing
work), electrically (work done by moving charges), by heating or by
radiation (like light or sound)
◉ When a system changes, energy is transferred. Answer: It can be
transferred into or away from the system, between objects in the
system or between different types of energy stores. Closed systems
are where neither matter nor energy can enter or leave. The net
change in the total energy of a closed system is always 0
◉ kinetic energy. Answer: energy of motion - the greater an object's
mass and the faster it is going, the more energy there will be in its
kinetic energy store. Ek (j) = 1/2m(kg)v(m/s) squared
◉ Raised objects store energy in gravitational potential energy
stores. Answer: lifting an object in a gravitational field requires
work, causing an energy transfer to the the GPE store of the object.
Ep(j) = m(kg)g(n/kg)h(m)
,◉ Falling objects transfer energy. Answer: Falling objects transfer
energy from its GPE store to its kinetic energy store. When there's
no air resistance, energy lost from the GPE store = energy gained in
the kinetic energy store
◉ Stretching transfers energy to elastic potential energy stores.
Answer: As long as the limit of proportionality has not been
exceeded, Ee (j) = 1/2 k (N/m) e (m) squared
◉ specific heat capacity. Answer: the energy required to raise the
temperature of one gram of a substance by one degree Celsius. E
(j) = m(kg) c(j/kgdegree) theta (degrees Celsius)
◉ Conservation of energy principle. Answer: Energy can be
transferred but can never be created of destroyed
◉ Dissipated energy. Answer: energy used up in a system, typically
lost due to work done by friction, 'wasted energy'
◉ Phone energy. Answer: When you use the phone, energy is
usefully transferred from the chemical energy store of the battery in
the phone, but some of this energy is dissipated to thermal energy
◉ Closed system energy transfer. Answer: A cold spoon is dropped
into hot soup in an insulated flask, which is then sealed. Energy is
,transferred from the thermal energy store of the soup to the useless
thermal energy of the spoon
◉ Power. Answer: The rate at which work is done (watts). P(w) =
E(j) / t(s)
◉ Powerful machine. Answer: One which transfers a lot of energy in
a short space of time
◉ Conduction occurs mainly in solids. Answer: Conduction is the
process where vibrating particles transfer energy to neighbouring
particles.
◉ Long definition of conduction. Answer: Energy transferred to an
object by heating is transferred to the thermal store, which is shared
across the kinetic store of the particles. The particles' collisions
cause energy to be transferred between particles kinetic energy
stores.
◉ thermal conductivity. Answer: the Mrs sure of the rate at which
thermal energy can travel through a material
◉ Convection occurs only in liquids and gases. Answer: Convection
is where energetic particles move away from hotter to cooler regions
, ◉ Convection longer definition. Answer: Unlike in solids, the
particles in liquids and gases are able to move. When you heat a
region of a gas/liquid, the particles move faster and the space
between particles increases. This causes the density of the region to
decrease. Because they can flow, the warmer and less dense region
will rise above denser cooler regions. If there is a constant heat
source, a convection current will be made
◉ Radiators - convection currents. Answer: Energy is transferred
from the radiator to nearby air particles by conduction. The air by
the radiator becomes warmer and less dense. This warm air rises
and is replaced by cooler air. At the same time, the previously heated
air transfers energy to the surrounding and cools, becomes denser,
and sinks. This cycle repeats and causes a flow of air to circulate
around the room
◉ How to reduce unwanted energy transfers. Answer: Lubrication
and thermal insulation
◉ Lubrication reduces frictional forces. Answer: When something
moves, there's at least one frictional force acting on it, causing some
energy to be dissipated. For objects that are rubbed together,
lubricants reduce the fiction between the object's surfaces when
moved. Lubricants tend to be liquids (like oil) to flow easily between
objects and coat them
