Chemistry test 3

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How to find the amount of moles of 10.0g of AL

(Grams of AL)(1mol/amu in grams) = Moles

10.0g)(1 mol/ 26.89g)= 0.37064
How to find amount of atoms in a specified amount 10.0g of AL

First convert 10.0g into mol = .37064 then find amount of atoms with avagadros number

(.37064mol AL)(6.022X10²³/1 mole AL)

Keep number in scientific notation
Steps to get from grams of a substance to number of atoms
- Grams to mole,
- Moles to atoms (avogardos number)
Equation for precent composition

Percentage = Part/whole X 100
How to find percent composition of carbon in C₂H₅OH
- Percent = Part/whole X 100
- First find the amu of the entire compd (46.068g/mol)
- Multiple C by number of
Empirical Formulas

The simplest whole number ratio of atoms in a molecule

H₂O_{2 ->}HO
How to calculate empirical formulas from percent compositions?

Do this for all compositions, then divide all #s by the lowest amount of moles.

Multiply numbers by 2 or 3 to get whole numbers
Molecular formula

A multiple of the emp formula
How would you find the molecular formula of 252g of C₅H₃ ?
- Find the mass of the 5C and 3H = 63.074 g/mol
- Then divide is with the mass you have.
then multiply emp1rical form by 4
How would you find molecular formula from percent compositions?

ex %49.47C, 5.191%H, 28.86%N, O, molec mass of 194g
- Make the %comp into grams.
- Divide that by elements amu
then you would divide that by the smallest amount of grams/mol
Determining amount of moles formed/ needed when reacting
- First you need to balance the equation.
- Then you use equivalence factors (4.30 moles of C₃H₈ and O₂= 4.30mol C₃H₈= 5mol O₂)
Then convert

Author

michaelirby98

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Card Set

Chemistry test 3

Description

chem

Updated

2014-04-14T20:43:24Z

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