Matter Flashcards
(29 cards)
How do particles behave/ react to a change in temperature?
- As temperature increases
- particles gain kinetic energy- the speed of the particles increase
- When these particles collide with objects, each collision exerts a tiny force
- These add up to an average force per unit area
What does it mean to describe temperature as a “macroscopic property”?
- Temperature applies to the gas as a whole
- It would not be correct to describe individual particles of gas as having a particular temperature
- All that happens to the particles, is that they increase in speed
How does the behaviour of particles affect pressure?
“As temperature increases the pressure increases”
- As temperature increases
- particles gain kinetic energy- the speed of the particles increase
- When these particles collide with objects, each collision exerts a tiny force
- These add up to an average force per unit area
- This increases the pressure exerted by the gas
What does it mean to describe pressure as a “macroscopic property”?
- Pressure applies to the gas as a whole
- It would not be correct to describe individual particles as having a particular pressure
What is the relationship between the pressure and volume of a gas, when temperature is kept constant? What equation is sued to show this?
[PV = consant] OR [P1V1 = P2V2]
- Pressure is inversely proportional to volume*
- As the volume decreases
- The average speed of the gas particles are still the same (because temp is kept constant)
- But the gas particles now have less distance to travel between collisions
- The frequency of collisions between the gas particles increase
- While the average force of each collision stays the same
- Therefore, the pressure exerted by the gas increases
What does the term sublime mean? Give an example of a compound that undergoes this process?
A compound that sublimes is one that changes directly between the solid and gas states
E.g, solid Carbon dioxide (dry ice)
What is meant by the term “melting”?
The process by which a substance changes from a solid to a liquid
- A solid turns to liquid (by melting) at temperatures above the melting point
- A liquid turns to solid at temperatures below the melting point
What is meant by the term “boiling”/ evaporation?
The process by which a substance changes from a liquid to a gas
- A liquid turns to gas (by boiling) at temperatures above the boiling point
- A gas turns to liquid at temperatures below the boiling point
What is meant by the term “condensing”?
The process by which a substance changes from its gas state to liquid
What is meant by the term “freezing”?
The process by which a substance changes from its liquid state to a solid
Why is it some substances don’t have a specific melting/ boiling point? OR it doesn’t match the compounds standard mp/bp?
-The substance is impure
;melts over a range of temperatures and boils over a range of temperatures
What is meant by the term “specific latent heat”?
The specific latent heat of a substance is the amount of energy needed to change 1 Kg of the substance from one state to another with NO CHANGE in temperature
What is the specific latent heat of FUSION?
The amount of energy needed to change 1 Kg of a substance from a solid into a liquid (with no change in temp)
What is the specific latent heat of VAPORISATION?
The amount of energy needed to change 1 Kg of a substance from a liquid into a gas (with no change in temp)
Why does the temperature remain constant at the point of melting/boiling?
- While a sample of a pure substance is melting/boiling
- the absorbed energy is needed to increase the separations between the particles
- only when the entire sample has changed state will further absorption of thermal energy cause its temperature to increase again
Why does the temperature remain constant during condensation/ freezing?
- during freezing
- thermal energy is lost to the environment
- However the energy is solely used to change the state from gas-liquid or liquid-solid
- When the state has changed fully only then does the release of energy cause a decrease in temperature
What formula is used to calculate the thermal energy transferred for a change of state?
E = m L
Energy transferred: (J)
Mass of substance: (Kg)
Specific latent heat: (J/Kg)
What is density?
The mass per unit volume of that substance
What is the formula for density?
Density = mass / Volume
density: Kg m-3
g cm-3
g mL-1
How do you convert from g cm-3 to Kg m-3?
1 g cm-3 = 1000 Kg m-3
What method is used for measuring the mass of a solid cuboid?
Measure the mass using a balance
What method is used for measuring the mass of a solid with irregular shape?
Measure the mass using a balance
What method is used for measuring the mass of a liquid?
- Use a balance to find the mass of a measuring cylinder
- Pour the sample into the cylinder
- Measure the mass of cylinder+sample
- Find the difference between the two mass measurements
What method is used for measuring the volume of a solid cuboid?
- Measure the sample’s dimensions using a ruler or other suitable instrument
- Use these measurements to calculate the volume of the sample
