5) Solids, Liquids & Gases

Question 1

Units for temperature, energy, mass, density, area, volume, velocity, acceleration, force, pressure

Answer 1

temperature: degree Celsius (°C) or Kelvin (K)
Energy: Joule (J)
mass: Kilogram (kg)
density: kilogram/metre cubed (kg/m3)
distance: metre (m)
area: metre squared (m2)
volume: metre cubed (m3)
velocity: metre per second (m/s)
acceleration: metre per second squared (m/s2)
force: newton (N)
pressure: pascal (Pa)

Question 2

Density

Answer 2

The mass per unit volume of a material

Question 3

Calculating density

Answer 3

Density (kgm^-3) = mass (kg)/ volume (m3)
Measured in g/cm3 or kg/m3

Question 4

Investigating density - depending on shape

Answer 4

1. Weight object on balance, note down mass
2. Use a ruler, vernier calipers, micrometer to measure dimensions
3. Repeat measurements, take the average (accuracy)
4. Calculate the volume of the object (regular shape)
5. Calculate density

Question 5

Investigating density - irregular shape

Answer 5

1. Weigh object on balance
2. Fill the eureka can with water up to a point just below the spout
3. Place an empty measuring cylinder below its spout
4. Carefully lower the object into the eureka can
5. Measure the volume of the displaced water in the measuring cylinder
6. Repeat these measurements and take an average before calculating the density

Question 6

Pressure

Answer 6

The concentration of a force or the force per unit area

Question 7

Calculating pressure

Answer 7

pressure (Pa) = force (N)/ area (m^2)

Question 8

Pressure in fluids

Answer 8

-when an object is immersed in a fluid, the fluid will exert pressure, squeezing the object
-pressure is exerted evenly across the whole surface of the fluid in all directions, creates forces against surfaces
-These forces act at 90 degrees (at right angles) to the surface

Question 9

Calculating pressure difference in a liquid

Answer 9

Pressure (Pa) = height (m) x density (kg/m^3) x gravitation field strength (N/kg)

Question 10

Solids characteristics

Answer 10

-high density
-regular pattern
-vibrate around a fixed position
-low energy
-definite shape
-definite volume

Question 11

Liquids characteristics

Answer 11

-medium density
-randomly arranged
-move around each other
-greater energy
-No definite shape
-A definite volume

Question 12

Gas characteristics

Answer 12

-low density
-randomly arranged
-move quickly in all directions
-highest energy
-No definite shape
-No fixed volume
-highly compressible - large gaps between particles

Question 13

Heating a system causes:

Answer 13

-change energy stored in a system by increasing KE of its particles. This:
-causes temperature of system to increase
-produce a change of state

Question 14

Practical: Investigating Changes of State

Answer 14

1. Place the ice cubes in the beaker
2. Place the thermometer in the beaker
3. Place the beaker on the tripod and gauze, heat using bunsen burner
4. take regular temperature measurements
5. Continue whilst the substance changes state (from solid to liquid)
6. Plot graph of temp against time

Question 15

Specific heat capacity

Answer 15

The amount of energy required to raise the temperature of 1 kg of the substance by 1 °C

Question 16

Calculate change in thermal energy

Answer 16

Change in thermal energy (J) = Mass (kg) × Specific heat capacity (J/kg °C) × Change in temperature (°C)

Question 17

Brownian motion

Answer 17

The random motion of particles suspended in a fluid (a liquid or a gas) resulting from their collision with the fast-moving atoms or molecules in the fluid

Question 18

Absolute zero

Answer 18

-The temperature at which the molecules in a substance have zero kinetic energy
-absolute zero = -273 Celsius

Question 19

The Kelvin Scale

Answer 19

-Begins at 0
-0K = -273C

Question 20

Temperature and speed of molecules

Answer 20

-hotter the gas, faster the molecules move
-increase kinetic energy
-molecules collide with the surface of the walls more frequently
Kelvin temperature is proportional to average kinetic energy of its molecules

Question 21

Boyle’s law

Answer 21

For a fixed mass of gas, at constant temperature, the pressure is inversely proportional to the volume
P1V1 = P2V2

Question 22

Charles law

Answer 22

For a fixed mass of gas, at constant pressure, the volume is directly proportional to the temperature
V1/T1 = V2/T2

Question 23

Pressure Law

Answer 23

For a fixed mass of gas at constant volume, the pressure is directly proportional to the temperature
P1/T1 = P2/T2

Question 24

Ideal gas assumptions

Answer 24

-gas particles are very small - volume of particles is much smaller than volume occupied by gas
-gas particles move in random motion and in all directions with a distribution of speeds
-number of particles are large
-gas particles undergo elastic collisions and no KE is lost
-time duration of the collisions is small compared to the time in between collisions
-no forces/ interactions between the particles other than when they collide