C4 Chemical calculations

C4 Chemical calculations

What is Ar?

It is the mean relative mass in grams of isotopes of an element compared to carbon-12.

What is a mole?

Moles are relative atomic masses in grams.

The formula for the number of moles

number of moles = mass / Ar or Mr

What do symbol equations tell you?

Symbol equations tell you the number of moles of a substance involved in a reaction.

They can be deduced from the masses of chemicals involved and the ratio of the number of moles.

What is a limiting reactant?

It is a reactant used up first not in excess.

What is percentage yield?

It compares masses of products the reaction makes with the theoretical mass made.

Percentage yield formula

percentage yield = actual mass made / maximum theoretical product mass possible

Factors affecting percentage…