Energy and Kinetic Energy

Heat

is energy which moves from a high temperature object to a lower temperature object because of a temperature difference

Kinetic Energy

is the energy of particles due to their motion.

Potential Energy

is the energy of particles due to the distance between them

Total internal energy

is the sum of the kinetic and potential energy of all the particles within an object

Explain the difference between heat and total internal energy

define both terms, and then heat only occurs during energy transfer whilst an object will always have total internal energy regardless if it is zero

Explain how the potential energy and total internal energy of a substance changed when it is melted/vaporised

the average distance between particles increase during melting/vaporisation, meaning potential energy increase. Kinetic energy remains constant.Since potential energy is increased total internal energy is increased.

Explain how freezing and condensation is affects total internal energy

The average distance between particles decreases during freezing and condensation. Contraction decreases the potential energy of the particles. Kinetic energy remains constant. Therefore total internal energy decreases.

Temeperature

is a measure proportional to the kinetic energy of the particles within a substance

if an object is bigger what does this mean for the potential energy

more potential energy

Describe the energy transfers that occur when a can of coke at 40 degrees celcius is placed in a bucket of ice water

Heat transfers from the higher temperature coke to the lower temperature water. Coke lowers in temperature, whilst water increases in temperature until thermal equilibrium is reached.

Explain why it is possible for air and water to exist in thermal equilibrium at 25 degrees celcius when 1kg of air has significantly higher internal energy than 1kg of water.

Temperrature is defined by average KE of particles and has nothing to do with total energy of many particles. Average KE is equal at the same temperature. 1kg of gaseous air occupied a much larger volume and therefore has much greater total PE. Therefore IE of air is greater, despite a similiar number of particles

Diffusion

Diffusion is where particles intermingle as a result of their kinetic energy of random motion (KMT). If two gases in containers are initially seperated by a partition, and the partition is lifted then the particles will diffuse.

A teacher sprays a can of deodorant at the front of a large lecture theatre and within a few seconds the front row of students can smell the deodorant. Within a few minutes all of the students in the lecture theatre can smell the deodorant. Use the Kinetic Molecular Theory of matter to explain how the deodorant moves around the room.

When deodorant is sprayed, it releases gas molecules with significant kinetic energy. According to the Kinetic Molecular Theory, these gas particles are in constant random motion. The particles move from a region of high concentration near the spray toward regions of lower concentration throughout the room by the process of diffusion. As the deodorant molecules travel, they undergo frequent elastic collisions with surrounding air molecules (such as nitrogen and oxygen), causing their paths to change direction. Because gas particles have large intermolecular spaces and high average speeds, diffusion occurs rapidly, allowing the smell to reach the back of the room quickly.

Kelvin Temperature Scale

The volume of an ideal gas decreases linearly with a decrease in temperature (until the gas changes phase

-273 degrees celcius

is called absolute zero. theoretically no temp can go below absolute zero bc the speed of the particles is zero at -273 degrees celcius

K to C

K= C+273

Use KMT to explain how a balloon decreases in size as it is cooled.

The decrease in temperature means that the average kinetic energy of particles also decreases. Particles move slower meaning that they impact the wall of the balloon with less force, and therefore less pressure exerted by the particles in the balloon. The pressure inside the balloon is less than the atmospheric pressure meaning the volume decreases.

Specific Heat Capacity

is the amount of energy required to increase the temperature of 1kg of the substance by 1K or 1 degrees celcius

If a material has a high specific heat capacity…

it takes a large amount of energy to increase it’s temperature

Material with a high specific heat release

a large amount of energy is lost when its temperature is decrease

SHC is a property of

the material