Molecular and Empirical Formulas & Theoretical and Actual Yeild Flashcards
molecular formula
chemical formulas that show the actual elemental symbols and numbers of the atoms in a molecule
empirical formulas
formula that gives the most reduced whole number ratio of each atom in a chemical formula
percent composition
tells you how much of one atom a molecule is made of
-must know molecular weight and the atom in questions weight, divide them and multiply by 100
What are the two ways a percent composition question appears on DAT?
1) given a molecule’f formula and asked for a specific elements percent
2) given the mass percent of each element, and have to determine the molecules formula
Why do we care about empirical formulas?
Bc when we analyze an unknown sample the machine doesn’t give us a formula. It gives us a list of elements and their percentage present in the sample. We can convert those %s into an empirical formula, and later use mass spectrometry to help convert it into a molecular formula
Limiting reactant
the reactant that runs out first, the amount of product you can get in a reaction is dependent on the limiting reagent
theoretical yield
the amount of product you SHOULD get in a given reaction (if everything goes perfect). This is what you would calculate to obtain
How do you find theoretical yield?
identify the limiting reactant and then calculate
actual yield
the amount of product that you actually get when you run an experiment. You will measure this
What is the equation to find % yield?
% yield = actual/theoretical x 100
Compare the equation to find % yield and % error
% yield = actual/theoretical x 100
% error = (actual-theoretical)/theoretical x 100
