Chapter 3 Flashcards
What is avagadros number?
6.022 x10^23
What is the atomic mass?
# of periodic table that is for 1 mole
How do you find molecular (molar) mass?
add atomic masses of all atoms
What is molar mass also called?
formula mass
How to find percent composition by mass?
= ( mass of element / mass of sample ) x 100
How to find percent mass for a molecule of a compound?
= {[(atoms of element)(atomic mass)] / molecular mass of compound} x 100
How to find percent mass for a mole of a compound?
= {[(atoms of element)(molar mass of element)] / mass of 1 mole of compound} x 100
How do you find the empirical formula?
- convert whatever you have to moles
2. divide by smallest number
What does the law of conservation of mass say?
cannot create or lose any atom in a reaction
- balancing equations represent accurate molecular level
What is the limiting reactant?
What is the excess reactant?
limiting = reactant used completely up
- present in lower # of moles
excess = reactant with some left over
- present in higher # of moles
Does limiting or excess reactant determine how much product is produced?
limiting
How do you find the limiting reactant?
convert one reactant to another to see how much reactant needs
if number is larger than what u have then the compound you converted to is limited
What is the theoretical yield?
amount of product that must be obtained if no losses occur (all limiting reagent is used)
What is the actual yield?
amount of product obtained experimentally
What is the percent yield?
relates actual yield to theoretical yield
