Chem 403 class 4

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1.00 grams equal how many mass units

6.022 x 10²³
What is Avogadro's number?

6.022 x 10²³
one mole of an element is......... atoms of an element

6.022 x 10²³
one mole of a compound is............moles of the compound

6.022 x 10²³
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 10²³) 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 CO₂and 0.1500g H₂O

Mass of CO₂x mass fraction C in CO₂
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 H₂ react with one molecule of O to form 2 molecules of H₂O.
Can also be read as:

Two moles of H₂ react with 1 mole of O₂ to form 2 moles of H₂O.
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

21066

Card Set

Chem 403 class 4

Description

Notes from class 4 chem 403

Updated

2010-05-28T20:13:47Z

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