C4: Chemical Calculations Flashcards
What is the relative formula mass (Mr) of a substance?
The sum of the relative atomic masses of atoms in the numbers shown in the formula
What is the mass of one mole of a substance in grams equal to?
The relative formula mass (Mr)
What is the value of Avogadro’s constant?
6.02 x 10^23
What is the limiting reactant?
The reactant that is completely used up
Why may the percentage yield of a reaction not always be 100%?
It could be reversible, some product may be lost when it is separated from the reaction mixture and some reactants may react in different ways than expected
What is the formula for percentage yield?
(Mass of product made / maximum theoretical mass) x 100
What is atom economy?
A measure of the amount of starting materials that end up as useful
What is the formula for atom economy?
(Mr of desired products / sum of Mr of all reactants) x 100
What is the volume of 1 mole of any gas?
24dm^3
What is the formula for moles?
Mass / Mr
What is the formula for calculating the volume of a gas?
Moles x 24
Why is it important to consider atom economy?
Raw materials being expensive, so it is less profitable, less sustainable to use large quantities and waste products can be expensive to get rid of
What are solutions to problems about atom economy?
Use more efficient reaction or find a use for the waste products
