P1.2 Changes Of State Flashcards
What is density?
Density is the property of a material which is how much mass there is per unit of volume
What is the formula for density?
Density(kg/m3) = mass(kg)/volume(cm3)
What does density determine?
Whether an object floats or sinks. If it has a lower density than water it will float
Why is a solid denser than a liquid?
A so,I’d has more particles in an area than a gas or a liquid. The mass of 1cm3 of a solid is also greater so it’s density is greater
What does the law of conservation of mass state?
The mass of a system does not change unless you add or remove material. Particles do not disappear or appear
How do you measure the volume of an irregular solid?
Fill an eureka can to just under the spout by slightly over filling it and letting it drain out.
Place a measuring cylinder under the spout
Gently lower the object into the eureka can
Measure the volume of liquid displaced
Repeat for reliability
How do you measure the volume of a regular solid accurately?
Use a vernier calliper to measure the side lengths.
Then use an electronic mass balance
What is temperature?
How hot or cold something is. Or the average kinetic energy of the particles in a substance of material
What is absolute 0?
-273 Celsius
What is the difference between energy and temperature?
Energy depends on the arrangement of particles and how fast they vibrate. Temperature is the average kinetic energy of each particle. This means that a swimming pool possessed more energy because it has more particles than a cup of tea but it’s temperature is lower
What happens when a substance is heated?
The energy stored changes so temperature increases
A chemical reaction occurs eg combustion
A physical change occurs such as state change
What 3 things do the amount by which temperature changes depend on?
The amount of energy/ temperature change
Mass of the material
The specific heat capacity of the material/ the material it is made from
What is specific heat capacity?
The energy needed to raise the temperature of 1kg of a substance by 1K/C.
It is a measure of the resistance of a material to heat change
What does heating do?
Increase the internal energy of particles, eg vibration or motion
Formula for specific heat capacity
Delta E(J) = Mass(kg) x Specific heat capacity(J/KgC) x Delta T(C)
Why is waters high specific heat capacity useful?
It can be used for central heating because it is less resistant to temperature change(decrease). Oceans will also not freeze because of this
What happens at the Fakt section on a graph of temperature of water being heated?
The energy is being transferred to break the intermolecular bonds so the temperature does not increase. Internal energy increases while temperature doesn’t
Describe the particle model of a solid?
Particles are in a regular and fixed position held together by very strong intermolecular forces. They do not have much energy so they vibrate when they gain energy
Describe the particle model in a liquid
The particles are close together but can move around each other in an irregular arrangement. The forces of attraction are strong. The particles move in random directions at low speeds and can flow
Describe the particle model of a gas
Particles are in a random arrangement with very weak intermolecular forces between them. They have more energy in their kinetic energy stores so they move in random directions at high speeds
What happens when enough energy is provided to a solid or a liquid?
Solid - particles vibrate faster until the forces are overcome and the particles start to move around each other
Liquid - the particles move faster because they have more energy in their kinetic stores. Eventually the forces are overcome
What is specific latent heat of fusion?
The energy transferred to cause 1 kg of a solid to turn to liquid
What is specific latent heat of vaporisation?
The energy transferred to cause 1kg of a liquid to turn to gas
What is the difference between specific latent heat and specific heat capacity?
Latent heat is about changing state while capacity is about temperature
Formula for specific latent heat
Energy for state change(j) = mass(kg) x specific latent heat(J/kg)
What is it specific?
Each material has a different latent heat and heat capacity
