P6 - Molecules and Matter Flashcards
What is a boiling point?
temperature at which a pure substance boils or condenses
What is Boyle’s law?
for a fixed mass of gas at constant temperature, its pressure multiplied by its volume is constant
What is density?
mass per unit volume of a substance
What is freezing point?
the temperature at which a pure substance freezes
What is internal energy?
The energy of the particles of a substance due to their individual motion and positions
What is latent heat?
the energy transferred to or from a substance when it changes state
What is melting point?
The temperature at which a pure substance melts
What is physical change?
a change in which no new substances are produced
What is pressure?
force per unit cross-sectional area for a force acting on a surface at right angles to the surface. The unit for pressure is the pascal (Pa) or newton per square metre (N/m²)
What is specific latent heat of fusion Lf?
energy required to change 1kg of a substance from a solid to a liquid with no change in temperature
What is specific latent heat of vaporisation Lv?
energy required to change 1kg of a substance from a liquid to a gas with no change in temperature
A block of aluminium occupies a volume of 16cm³ and has a mass of 20.5g. What is the density?
1.3g/cm³
Calculate the volume of a chemical that has a mass of 3g and a density of 3g/cm³
1cm³
Gold has a density of 19g/cm³, Silver has a density of 10g/cm³. An Olympic medal has a volume of 80cm³. Which medal has the greatest mass?
Gold = 1520g
Silver = 800g
Gold medal has a greater mass
What is a solid?
A solid is a substance with a fixed shape and volume, it is more dense than gases and liquids. it cannot flow, It’s particles can only vibrate. It cannot be compressed. It’s particles are very close together and are fixed in a rigid arrangement
What is a liquid?
A liquid is a substance with no fixed shape but with a fixed volume, they are less dense than a solid but more dense than a gas. They can flow. They cannot be compressed. It’s particles are close together but are not fixed in a rigid arrangement, they are free to move
What is a gas?
A gas is a substance with no fixed shape or volume, it is less dense than solids and liquids and it can flow. It can be compressed. It’s particles are far apart.
What is the change from solid to liquid called?
melting
What is the change from liquid to solid called?
solidification
What is the change from liquid to gas called?
vaporisation
What is the change from gas to liquid called?
condensing
What is the change from gas to solid called?
deposition
What is the change from solid to gas called?
sublimation
What is the difference between boiling and evaporating?
Boiling is when all the particles have enough energy to turn into gas, evaporation is when only the particles at the surface have enough energy to turn into a gas.
What is conservation of mass when changing state?
When changing state a substance’s mass will not change.
What can change the melting and boiling point of a substance?
Any impurities in a substance will affect the melting and boiling point of the substance?
Describe and explain a temperature-time graph of a substance being heated
In solids, the particles are arranged in a regular pattern and vibrate about fixed positions. As the solid is heated the particles begin to vibrate faster about the fixed positions. Therefore, temperature increases. As the temperature increases, the particles eventually gain enough energy to break up the regular structure and the solid melts. While the solid is melting, the heat energy supplied is sued to break the bonds in the solid not to make the particle move faster. Therefore the temperature stays constant until all the solid has melted. When the liquid is heated the particles gain energy and move faster. Therefore the temperature increases. As the temperature increases the particles eventually gain enough energy to move apart completely and the liquid boils. While the liquid is boiling, the heat energy supplied is used to overcome the forces between the particles in the liquid not to make the particles move faster. Therefore the temperature stays constant until all the liquid has turned to a gas. At this point the liquid has completely turned to a gas and any further heating will once again make the particles move faster.
What is internal energy?
Internal energy is the total kinetic and potential energy of all the particles that make up a system