3: The Particle Model Flashcards
What is the equation for calculating density?
ρ = m/v
ρ : density (kilograms per metres cubed, kg/m³
m: mass (kilograms, kg)
v: volume (metres cubed, m³)
What is the difference between a chemical and physical state change?
A chemical state change cannot be reversed whereas a physical state change can be reversed and the material recovers its original properties.
Define internal energy.
Internal energy is the total kinetic energy and potential energy of all the particles (atoms and molecules) that make up a system.
What is the equation for calculating change in thermal energy?
ΔE = mcΔθ
ΔE = change in thermal energy (Joules, J)
m = mass (kilograms, kg)
c = specific heat capacity (joules per kilogram per degree Celsius, J/kg°C)
Δθ = temperature change (degrees Celsius, °C)
What is latent heat?
Latent heat is the energy needed for a substance to change state. When a change of state occurs, the energy supplied changes the energy stored (internal energy) but not the temperature.
What is specific latent heat?
The specific latent heat of a substance is the amount of energy required to change the state of one kilogram of a substance with no change in temperature.
What is the equation for calculating energy required for a change of state?
E = mL
E: Energy required (Joules, J)
m: mass (kilograms, kg)
L: specific latent heat (Joules per kilogram, J/kg)
What is specific heat capacity?
The specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius.
How is pressure related to temperature in gases?
The higher the temperature, the more kinetic energy the particles have therefore the more collisions there are between the particles and the walls of the container. This henceforth, means an increase in pressure.
Required practical activity 17.1: What apparatus is required to determine the density of a regularly shaped object.
- 30cm ruler marked off in mm
- digital balance
- selection of regularly shaped objects
Required practical activity 17.1: State a method you could use to determine the density of a regularly shaped object.
1: For each of your selected objects measure and record the length, width and height.
2: Calculate the volume of each object
3: Use the balance to measure and record the mass of each object.
4: Record your results in a table containing length, width, height, volume, mass, density.
5: Calculate and record the density of each object using: Density = mass / volume.
6: Standard units of density are kg/m³, use the data to calculate density in these units.
Required practical activity 17.2: What apparatus is required to determine the density of an irregularly shaped object.
- a digital balance
- a displacement can
- various measuring cylinders
- a beaker of water and an extra empty beaker
- paper towels
- a selection of irregularly shaped objects
Required practical activity 17.2: State a method you could use to determine the density of an irregularly shaped object.
1: Measure the mass of one of the irregularly shaped objects.
2: Record your results in a simple table.
3: Put the displacement can on your desk. Put an empty beaker under the spout and fill the can with water. Water should be dripping from the spout and you should wait until you see this stop.
4: Put a measuring cylinder that you think will give the most accurate reading under the spout instead of the beaker.
5: Very carefully lower the object into the displacement can so that it is completely submerged.
6: Measure the volume of the collected water
7: Calculate and record the density of the object.
8: Repeat the activity for some other objects. Remember to refill the can each time.
9: Repeat the activity for some other objects. Remember to refill the can with water each time.
Required practical activity 17.3: What apparatus is required to determine the density of a liquid?
- a digital balance
- a 100cm³ measuring cylinder
- a sugar solution of unknown concentration
Required practical activity 17.3: State a method you could use to determine the density of a liquid.
1: Measure the mass of the empty measuring cylinder
2: Record your results in a table with mass of the empty measuring cylinder in g, volume of liquid in cm³, mass of cylinder plus liquid in g, mass of liquid in g, density of liquid in g/cm³.
3: Pour about 100 cm³ of the sugar solution into the measuring cylinder
4: Measure and record the mass of the measuring cylinder and liquid. From this calculate and record the mass of just the liquid.
5: Calculate the density of the liquid.
6: Standard units of density are kg/m³. Use the data above to calculate the density of the liquid in these units.
