P14 - particle model
Density
Internal energy and changes of state
States of matter
Specific heat capacity
particle motion in gases
Specific latent heat
Density
Measuring density
Density is a measure of how compact an object is
p( kg/m^3)= m(kg)/v(cm^3)
Measuring the density of a liquid
To measure the density of the liquid you must measure the volume of the liquid in a measuring cylinder and the put it on a balance to measure the mass of the liquid by measuring the mass of the empty cylinder and then with the liquid and subtract them. then you use the formula
Measuring density of the solid
First you put the solid on a weighing scale and then measure its mass. then you must get a eureka can filled with water. Then you get the solid and put it in the can and then you can place a measuring cylinder next to the spout to let water go in. Then you measure the volume of the water which it is the volume of the solid and then you use the formula
States of matter
Kinetic theory of matter
Density of solid liquid and gases
This is model that shows how particles that make up a substance behave. The force changes depending on the substance and the state
Solid
Liquid
Gas
They have a regular shape and structure and they have fixed position which means they have low kinetic energy
They have weak forces of attraction allowing them to move past each other. This means they have more kinetic energy than solid but less than gases
There are almost no forces of attraction between particles. This means they have the most kinetic energy store
Usually solid are the most dense as particles are tightly packed in each other. Then liquid are more dense than gases and gases are the least dense
What is specific heat capacity
What is internal energy
Increasing temperature
Changing states
Internal energy is the total energy that is stored in the potential energy and the thermal energy of the object. This means that heating the system is increases the internal energy of the object
Increasing the temperature means that internal energy in creases because you transfer more thermal energy. However the potential energy does not really change because even though the particles move and vibrate faster their relative position does not really change
Absolute zero - the coldest something can ever get is - 273 degrees Celsius
Temperature in c = temp in k - 273
Temperature in k = temp in c + 273
States change because when you heat them then they gain more ke which causes them to weaken and break bonds which causes the m to change states
Similarly when you reduce energy the particles lose ke. This leads them to form a bond and change state
Mass conservation
Number of particles do not change only the arrangement. This means that they conserve mass
Investigating specific heat capacity
Specific heat capacity is the amount of energy needed to raise the temperature of 1kg of a substance by 1 degrees C
thermal energy = mass x specific heat capacity x temperature
First you will have to measure the mass of a water in a container. Then you insert an immersion heater into the water and then you also have to place a thermometer in the container. You connect ammeter to the container. You set the voltage and then you start the circuit. You wait until temp increases by 10 degrees. Then you use the ammeter reading and the time taken and voltage and put it in the equation E = I x V x t. To make this more accurate you must wrap the container in thermal insulating material
What is specific latent heat
Specific latent heat is the amount of energy needed to change 1 kg of a substance to another state
Q = m x L
Q = change in thermal energy
m = mass in kg
L = Specific latent heat
Investigating change of state
First you must get a beaker with ice!p, thermometer and a stop watch and beaker. First you must place the thermometer in the beaker. Then burn the ice in beaker. Measure the temp every 20 seconds record the temp and state. Do this until the ice melts and it starts to boil. Plot the data on a graph
Gas pressure
This is when gases at high speed bang into each other and exert a force right angled to the surface. The outward pressure is the total force exerted by all the gas particle. Increasing temperature means that the particles collide more often at higher speed which increases the pressure and exerted force