the particle model of matter

Question 1

properties of solids and liquids

Answer 1

solids and liquids are incompressible because there are no gaps in between the particles

Question 2

structure of solids liquids and gases

Answer 2

solids contain particles in a fixed pattern and have a fixed size and shape

liquids have a fixed sixe but contain particles that are free to move, allowing them to change shape to fit their container

gases have large gaps between the particles, making them compressible and enabling them to change size and shape

Question 3

define density

Answer 3

its mass per unit volume

Question 4

density equation

Answer 4

density (kg/m^3) = mass(kg) /volume (m^3)

Question 5

what happens when energy is added to a system

Answer 5

its temperature will increase

at the melting point or boiling point, the energy being added causes the substance to change state not temperature

Question 6

define a change of state

Answer 6

a change of state is reversable

it is a physical change that alters the internal energy but not the temperature or mass. it is not a chemical change

Question 7

energy for a change of state equation

Answer 7

energy for a change of state(j) = mass(kg) x specific latent heat(j/kg)

Question 8

define the latent heat of fusion

Answer 8

the latent heat of fusion is the energy needed for a substance to change from solid to liquid (MELT)

Question 9

define the latent heat of vaporisation

Answer 9

the energy needed for a substance to change from liquid to gas

Question 10

what happens at certain pressures

Answer 10

at certain pressures, some substances have a boiling point that is the same or lower than their melting point

these substances change from a solid to a gas without having a liquid phase

this is called sublimation

Question 11

what is the reverse of sublimation

Answer 11

changing from a gas to a solid. this is called desublimation

Question 12

describe the particles in a gas

Answer 12

the particles if gas are in constant random motion and its temperatre is related to the average kinetic energy of the particles

Question 13

describe pressure in gases

Answer 13

when the particles of a gass collide with the walls of their container they exert a force on the wall, which is felt as pressure.

Question 14

how does increasing the temperature effect pressure

Answer 14

if the volume is kept constant, increasing the temperature increases the speed of the particles. this increases the frequency and force with which the particles hit the walls and increases the pressure

Question 15

what happens to the pressure of gases if temperature is kept constant

Answer 15

increasing the size of the container will reduce the pressure as the particles will collide with the walls less frequently

reducing the volume will increase the pressure, as the particles will collide with the walls more frequently

Question 16

what happens when work is done on a gas

Answer 16

when work is done on a gas it increases the internal energy of the gas and can cause an increase in temperature

Question 17

what happens when a bicycle is compressed

Answer 17

when a bicycle is compressed, the piston hits the gas particles giving them energy so temperature increases

as they are moving faster, the particles will collide with objects more frequently and the pressure will increase

Question 18

what other factor increases pressure

Answer 18

changing the volume of a gas can also change the pressure