States of Matter & Thermal Capacity Flashcards
All 42 cards in this deck
Describe the arrangement and movement of the particles in a solid.
Closely packed in a regular arrangement, vibrating about fixed positions.
Describe the arrangement and movement of the particles in a gas.
Far apart and randomly arranged, moving quickly in random directions.
What is the equation for density, with units?
density (kg/m³) = mass (kg) ÷ volume (m³)In terms of particle spacing, why is steam less dense than liquid water?
The space between the particles in steam is bigger than in water, so there are fewer particles per unit volume.
How do you convert a density in g/cm³ into kg/m³?
Multiply by 1000 (1 g/cm³ = 1000 kg/m³).
What are the steps to find the density of an irregular solid by displacement?
e.g. a lump of iron- Measure its mass on a balance.
- Part-fill a measuring cylinder with water, note the reading, immerse the solid and note the new reading; the difference is the volume.
- Calculate density = mass ÷ volume.
What are the steps to find the density of a liquid?
e.g. 25 cm³ of cooking oil- Put the empty measuring cylinder on the balance and zero (tare) it.
- Add the liquid; record its mass from the balance and its volume from the scale (read at eye level).
- Calculate density = mass ÷ volume.
Which measurements are needed to find the density of a regular solid block?
Its mass with an electronic balance, and its length, width and thickness with a ruler (volume = ).
Why can the displacement method not be used to find the volume of a piece of wood?
The density of wood is less than that of water, so it floats — less water is displaced than the volume of the wood.
What is sublimation?
A change of state from solid directly to gas.
Which change of state is from gas to liquid?
Condensing.
True or false? When ice melts, the mass of water formed is less than the mass of the ice.
False. Mass is conserved in any change of state.
Why are melting, boiling and condensing physical changes rather than chemical changes?
No new substance is made — the change can be reversed and the material recovers its original properties.
What two things can happen when a system is heated?
Its temperature rises, or it changes state.
When ice is melting, what is the energy supplied used for?
Breaking the bonds between the particles (increasing their potential energy), so the temperature does not rise.
When heating water raises its temperature, what happens to the energy supplied?
It increases the kinetic energy of the water particles.
True or false? The temperature of water rises while it is boiling.
False. The temperature stays constant at the boiling point because the energy is used to break bonds between particles.
Define specific heat capacity.
The energy needed to raise the temperature of 1 kg of a substance by 1 °C.
Define specific latent heat.
The energy needed to change the state of 1 kg of a substance, with no change in temperature.
What is the difference between specific heat capacity and specific latent heat?
Specific heat capacity involves a temperature change with no change of state; specific latent heat involves a change of state at constant temperature.
True or false? Specific heat capacity is measured in J/kg.
False. Specific heat capacity is measured in J/kg °C; J/kg is the unit of specific latent heat.
What is the equation for change in thermal energy, with units?
energy (J) = mass (kg) × specific heat capacity (J/kg °C) × temperature change (°C)What is rearranged to find the specific heat capacity ?
True or false? In the mass must be in kilograms.
True. Using grams gives an answer 1000 times too large.
What is the equation for the thermal energy needed for a change of state, with units?
energy (J) = mass (kg) × specific latent heat (J/kg)In specific latent heat, what change of state does 'fusion' refer to?
Melting — solid to liquid (or freezing, liquid to solid).
What is rearranged to find the specific latent heat ?
Give two ways of reducing unwanted energy transfer from a beaker of hot water in an experiment.
Add a lid or cover, and add lagging/insulation around the beaker.
What effect does using thicker insulation have on unwanted energy transfer?
It reduces the rate of energy transfer, so the contents cool down more slowly.
What property makes a material a good thermal insulator?
It is a poor conductor of energy, often because it traps air (e.g. foam, wool).
True or false? Insulating a container stops energy transfer from it completely.
False. Insulation only reduces the rate of unwanted energy transfer.
Which measurements are needed to determine the specific heat capacity of water?
The mass of the water, the temperature rise (start and end temperatures), and the energy supplied by the heater (joulemeter reading).
Other than adding insulation, give two improvements to the apparatus used to find the specific heat capacity of water.
Add a stirrer, use a more sensitive (digital) thermometer, or make sure the heater is fully submerged.
On a temperature–time graph for ice being heated, what does the flat section at 0 °C show?
The ice is melting — the energy supplied changes the state instead of raising the temperature.
At what temperatures does pure water melt and boil?
It melts at 0 °C and boils at 100 °C.
Describe the arrangement and movement of the particles in a liquid.
Close together in an irregular arrangement, moving randomly past each other.
In specific latent heat, what change of state does 'vaporisation' refer to?
Liquid to gas (or gas to liquid when condensing).
Which change of state is from liquid to solid?
Freezing.
Which two changes of state are from liquid to gas?
Boiling and evaporating.
In general, how do the densities of solids, liquids and gases compare?
Solids are usually the densest, liquids are less dense, and gases are the least dense.
What is the internal energy of a substance?
The total energy stored by its particles in their kinetic and potential energy stores.
How many cubic metres are there in 1 cm³?
m³ (0.000001 m³), because 1 m = 100 cm, so 1 m³ = 100 × 100 × 100 cm³.