reacting quantities

what is stoichometry

the ratio of the amount, in moles, of each substance in a chemical equation

what is a limiting reagent

the reactant that is not in excess, which will be used up first and stop the reaction

what is the percentage yield formula

(actual yield (mols) /theoretical yield (mols)) x 100

what is the atom economy formula

(sum of molar mass of desired products/sum of molar mass of all products) x 100

what are the two assumptions of percentage yield

-assumes all reactants are converted into products
-assumes that the maximum possible amount is the theoretical yield

why may the percentage yield of a reaction not be 100%

1. the reaction may have not gone to completion
2. other reactions (side reactions) may have taken place along side main reaction, giving unexpected products
3. purification may result in loss of product
4. the reactants were impure
5. there were products left in the apparatus

what are the two features of reactions with a high atom economy

-produce a large proportion of desired products and few unwanted waste products
-are important for sustainability as they make the best use of natural resources

How do you work out the limiting reagent in a reaction?

1.Write a balanced chemical equation.
2.Convert given amounts to moles

3. Use mole ratio from the equation to compare the moles you have with the moles required by the reaction
   4.Identify the limiting reagent
   5.Calculate the amount of product formed using the moles of the limiting reagent

when answering an exam question on why the percentage yield is not 100%, what is important

to link it directly to the question rather than stating the general reasons

what time of reaction has the greatest atom economy

addition