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Chem 403 class 4
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1.00 grams equal how many mass units
6.022 x 10
23
What is Avogadro's number?
6.022 x 10
23
one mole of an element is......... atoms of an element
6.022 x 10
23
one mole of a compound is............moles of the compound
6.022 x 10
23
moles to grams
Mass (g) + # moles x
# grams
mole
grams to moles
# moles+ # grams x
moles
# grams
formula to convert number of moles to the actual number of atoms or molecules of a substance using Avogadro's number
# molecules= # mol x (6.022 x 10
23
)
molecules
mole
To convert from weight to # of molecules first.......
the weight to moles then use Avogadro's # to determine the # of molecules
What can you calculate after you know that mass %?
you can calculate the fraction of a given weight of a compound due to a particular element.
Determining the formula of an unknown compound:
how do you do this?
by converting masses to moles, then determine the ratio of the elements in the compound
Whenever you are given a percentage of an element, you can....
assume any weight you want (100 is the easiest)
quickly how would you solve this:
A 0.2500g sample known to contain C, H, O is burned completely producing 0.3664g CO
2
and 0.1500g H
2
O
Mass of CO
2
x mass fraction C in CO
2
What are isomers?
different compounds with the same molecular formula
molecules to the left of the arrows are
reactants
molecules to the right of the arrow are
products
to satisfy conservation of mass the equation has to be
balanced
Two molecules of H
2
react with one molecule of O to form 2 molecules of H
2
O.
Can also be read as:
Two moles of H
2
react with 1 mole of O
2
to form 2 moles of H
2
O.
Limiting reactant:
the reactant that runs out first
excess
is the compound you are left over with after the limiting reagent stops the reaction
Author
mmb65
ID
21066
Card Set
Chem 403 class 4
Description
Notes from class 4 chem 403
Updated
2010-05-28T20:13:47Z
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