Gas Laws and the Mole Flashcards
What role does temperature play in the changing of states?
The higher the temperature, the more kinetic energy the particles have.
They can break free from each other at certain points (solid to liquid, liquid to gas).
Why are gases easy to compress?
Because their particles are much further apart than the other states.
What is meant by ‘diffusion’?
How would you demonstrate this phenomenon?
It is the spontaneous spreading out of a substance due to the natural movement of its particles.
To demonstrate, wet two cloths with HCl acid and ammonia solution respectively and place at either ends of a horizontal tube. White clouds of ammonium chloride form.
State Boyle’s law.
For a fixed mass of gas, Volume is inversely proportional to its Pressure, at a fixed Temperature.
State Charles’ Law.
For a fixed mass of gas, the Volume is directly proportional to its Kelvin Temperature at a constant Pressure.
State Gay-Lussac’s law of combining volumes.
When gases react, the Volumes consumed in the reaction have a simple whole no. ratio to each other and to the Volumes of any gaseous products.
(All volumes measured at a constant Temp. and Pressure)
What does Avogadro’s Law state?
That equal volumes of gases have an equal number of molecules (where temperature and pressure are constant to both).
What is the ‘mole’?
The amount of a substance that contains as many particles as there are atoms of Carbon-12 in 12g of Carbon-12.
(It is the SI unit of substance).
How many atoms of Carbon-12 are there in 12g of Carbon-12?
i.e. What is the Avogadro constant?
6x10^23
The unit of this constant is moles per litre. It is also called ‘L’
What does the ‘relative Molecular Mass’ (Mr) of a substance refer to?
The average mass of a molecule of the substance relative to 1/12th the mass of a Carbon-12 atom.
Name the assumptions of the Kinetic Theory of Gases.
- The diameters of particles are insignificant relative to the distance between them.
- There are no attractive/repulsive forces between particles.
- The particles are constantly in rapid motion, colliding w/ each other and w/ walls of container.
- That the (avg.) kinetic energy of the particles is proportional to the Kelvin Temperature.
- That all momentum is conserved after collisions (perfectly elastic collisions between particles).
What is an ideal gas?
What substances behave most like an ideal gas?
- Gases that obey all gas laws under all conditions of temperature and pressure.
- Noble gases. Hydrogen gas.
Why are the assumptions of the Kinetic Theory of Gases invalid?
At high pressure and low temperature:
- The diameters are no longer as insignificant.
- Intermolecular forces become more significant.
What is the assumption of the Theory that is incorrect at ALL conditions of temperature and pressure?
That all momentum is conserved in particle collisions.
What’s a volatile liquid? Give an example.
A liquid that is easily vaporised (room temperature or slightly higher, for example).
An example is acetone (a.k.a. Propanone)
