test unit 6 Flashcards
what is Avogadro’s hypothesis
if P1=P2, V1=V2, and T1=T2, then n1=n2
chemical formula
mole ratio of elements in a compound
empirical formula
based on data, simplest whole number mole ratio
molecular formula
actual mole ratio
how to find empirical formula
convert the grams of each element to moles
divide each elements moles by smallest moles
if ratios are whole numbers, those are subscripts, if not whole numbers multiply by 2/2 or 3/3 or something to make whole number
how to find molecular formula
determine the empirical formula
add up molar mass of empirical formula
given the molecular mass of the molecular formula, divide the MF mm by EF mm
use whole number and multiply by subscripts to get MF
percentage composition
total mass of element / total mass of compound multiplied by 100
remember if like (NH4)2O
the two distributes thing on outside distributes
relative mass
how many times heavier is one item compared to another
divide biggest/bigger by smallest one
find relative mass
Gas A=16.53g
Gas B= 41.33g
41.33g/16.43g= 2.5
Gas B is 2.5 times bigger than Gas A
calculate the percent composition of (NH4)2O
N2=28.02
H8=8.08
O=16.00
N=53.8%
H= 15.5%
O=30.7%
if you are given a compound how do u count the atoms
count the subscripts
do any elements have the same mm
NO
If you have a mole of 2 things,
have the same amount of particles
Empty Beaker: 48.73g
Beaker with Zinc: 50.43
Beaker with Zinc Chloride: 52.27g
Determine the Empirical formula of Zinc Chloride
KNOW HOW TO DO WITH DIFFERENT ELEMENTS
Find mass of Zinc and Chloride or other elements
MASS OF ZN
65.38g/1 mole = 1.7g/x mol
x=.0206 moles
MASS OF CL
35.45g/1mole=1.84g/x mol
x=.0519 moles
.0519 mol/.0206 moles=
2 moles of Cl/ 1 mol of Zn ZnCl2
How does relative mass tie into elements and the periodic table
Many substances combine with oxygen to form a type of compound called an oxide.
Analysis of these compounds allows us to determine the molar masses of the elements with which oxygen combines on the periodic table
