Stoichiometry 1

Question 1

What interested Avogadro?

Answer 1

Gay-Lussac’s law of combining volumes

Question 2

What do chemists measure amounts in?

Answer 2

Moles

Question 3

How can chemists use measurements to find formulae and write equations?

Answer 3

By working with amounts of chemicals that contain equal numbers of particles i.e atoms, molecules or ions.

Question 4

Define a mole

Answer 4

A mole of a substance is that amount of it which contains the Avogadro’s constant number of particles.

Question 5

Define Avogadro’s constant

Answer 5

Is the number of carbon atoms in exactly 12 grams of the C-12 isotope. This equals 6 x 10 (23) particles.

Question 6

Define Avogadro’s law

Answer 6

Equal volumes of all gases measured at the same temperature and pressure contain equal numbers of molecules.

Question 7

Define molar mass

Answer 7

The mass of one mole of a substance is its relative atomic mass (Ar) (or its relative molecular mass (Mr)) expressed in grams.

Question 8

No of Moles x Mr (Ar) =

Answer 8

Grams

Question 9

To convert moles to grams

Answer 9

Multiply by the Mr (Ar)

Question 10

To convert grams to moles

Answer 10

Divide by the Mr (Ar)

Question 11

Define molar volume

Answer 11

At s.t.p the volume of 1 mole of any gas is 22.4 litres (22,400cm3).

Question 12

To convert from moles to volume

Answer 12

Multiply by 22.4

Question 13

To convert from volume to moles

Answer 13

Divide by 22.4

Question 14

Grams –> Moles

Answer 14

Grams Moles Particles