Assorted

Question 1

How are Boyle’s Law, Charles’ Law, Avogadro’s Law, and Gay-Lussac’s Law related?

Answer 1

They are all derivations of the universal gas equation used when two variables out of PV=nRT are kept constant and one gas is subjected to two sets of conditions.

Charles: n and P constant
Gay-Lussac: n and V constant
Boyle: n and T constant
–> These can all be easily derived from the combined gas equation.

Then Avogadro’s is the V/n one, which you can derive from the universal gas equation but maybe just remember it.

Question 2

When can you use the combined gas equation?

Answer 2

The combined gas equation is used when you have one gas under two sets of conditions where the number of mols is constant. This can also be applied in situations where P, V, and T are constant to give three of the named gas laws. The combined gas equation may be used if all three (P, V, and T) change, so long as n is constant.

Question 3

What are the requried properties of a primary standard?

Answer 3

• Accurately-known formula
• Large molar mass (to minimise weighing errors)
• High state of purity
• Stable: doesn’t absorb water from the atmosphere
• Cheap + readily available

Question 4

What is a standard solution?

Answer 4

A solution where the concentration is accurately known

Question 5

What are the two ways to create or find the concentration of a standard solution?

Answer 5

• By dissolving a known amount of a primary standard into a known amount of water
• By reacting a solution with a solution of accurately known concentration.

Question 6

Aliquot vs titre?

Answer 6

Titre: solution of known concentration in burette.
Aliquot: solution of unknown concentration in pipette/beaker

Question 7

End point vs equivalence point?

Answer 7

End point: where the indicator changes colour

Equivalence point: where the reactants are present in their stoichiometric proportions

Question 8

Quantitative vs qualitative?

Answer 8

Quantitative: how much
Qualitative: what is it