Quantitative Chemistry Flashcards
How can the amount of reactants and used and products be measured?
Using relative atomic masses and relative formula masses.
What is the total mass of the reactants equal to?
The total mass of the products made.
How do you find the relative formula mass of a compound?
You add together the Ar values for all the atoms in the formula.
How do you calculate relative mass?
- Write out the equation for the reaction. Make sure it is balanced.
- Work out the relative masses of the substances needed in the calculation. Remember to multiply by the number of molecules that are present.
- Convert the relative masses into the units in the question.
- Find the ratio by dividing both numbers by the smallest relative mass.
- Find the mass of the unknown by multiplying the mass of the known by the ratio of the unknown.
What is percentage composition?
Percentage composition is just a way to describe what proportions of the different elements there are in a compound.
What is the actual yield?
The amount of product that is actually there to be used at the end of the manufacturing process.
What is the predicted yield?
The amount of product that might have been expected if nothing had got lost along the way.
What is the percentage yield?
A way of comparing the actual field with the predicted field. Its calculated using this formula: percentage yield = (actual yield x 100%) / predicted yield.
