chapter 3 calculations etc Flashcards
what is the main focus of organic chem?
The main element that is the focus of organic
chemistry is carbon
what are organic compounds made of?
Organic compounds are mainly made of C and
H, sometimes with O, N, P, S, halogens, and
trace amounts of other elements
what is the difference between organic and inorganic chem?
The difference between organic chemistry and
inorganic chemistry is an organizational
one…not a fundamental one.
types of hydro carbons
Carbon can form 4 covalent bonds • Comprised of only C and H Types of Hydrocarbons Alkane Only C-C single bonds Alkene Contain C-C double bonds Alkyne Contain C-C triple bonds
how are organic molecules drawn?
displayed or skeletal formula or 3D arrangement
describe displayed formula
Shows location of all atoms, including the hydrogens
describe skeletal formula
“Hydrogens attached to the carbon are removed, lines
represent bonds and when two lines meet we assume it
to be a carbon atom
describe 3D arrangement
Show arrangement of bonds in space
what are functional groups used for
When organic molecules contain more than carbon (C) and hydrogen (H) we can name the non-alkyl components based on the functional group • There are several commonly occurring functional group categories, which have specific atomic arrangements
know functional groups in chart (make cards of later)
ok
molar mass
Remember: The mass (in grams) of 1 mol of atoms of
an elements is numerically the same as its atomic mass
• We can apply the same concept to compounds
- The molar mass of a compound (in grams) is
numerically equivalent to its molecular mass
what is formula mass
The formula mass is the sum of the atomic masses (in u)
for each ion or atom contained in the chemical formula
for a compound
ex
6×(12.01u)+12×(1.008u)+6×(16.00u)= 180.16u
how can molar mass be used as a conversion factor
Molar mass serves to convert the mass (in g) to the
amount (in moles)
• Can be applied to the compound as a whole or the
individual elements that make up a compound
what is percent composition related to?
mass
• We can relate the mass of the individual elements in a
compound to the molar mass of the compound as a
whole
• Percent composition is a common term that is used to
describe the quantity of each element in a compound
per unit mass
what is percent composition NOT?
• Is NOT the % of atoms based on the ratio of atoms ie.
CH3CH2OH; oxygen does not compose 11% of ethanol
(1 atom of oxygen in a total of 9 atoms)
percent comp formula
Mass % of element X = mass of element X in 1 mol of compound/molar mass of compound x 100
what happens if you have 100g of sample?
the %X directly converts in to mass quantity
how can chemical formulas be used as conversion factors?
ex in notes
Chemical formulas have inherent relationships between
numbers or moles of atoms and molecules
what can chemical formulas be used to convert?
The ratio of atoms in a molecule can only be used to
convert between moles of one element or compound to
moles of another
• You can not directly convert masses!
how is an empirical formula found from data? steps?
- Convert the percentages to grams (no need to do
this if you are already given grams)
a)assume you start with 100 g of the compound - Convert grams to moles
a)use molar mass of each element - Write a pseudoformula using moles as subscripts
- Divide all by smallest number of moles
a) if result is within 0.1 of whole number, round to whole
number - Multiply all mole ratios by number to make all whole
numbers
a) if ratio is 0.5, multiply all by 2; if ratio is 0.33 or 0.67,
multiply all by 3; if ratio 0.25 or 0.75, multiply all by 4;
etc.
b) skip if already whole numbers
how is n calculated with empirical formula?
n= molecular formula molar mass / empirical molar mass
what is combustion analysis?
• Combustion analysis is a common analytical technique
used to determine the empirical formula of organic
compounds.
• These compounds are combusted in a furnace, and the
mass of CO2 and O2 is determined
what happens after combustion analysis?
After combustion, all of the carbon atoms in the sample
are found in the CO2, and all of the hydrogen atoms from
the sample are in the H2O
process of combustion analysis
Sample is combusted in a stream of O2. Produced CO2 and H2O are absorbed. The increase in mass of the absorbents is equal to the mass of CO2 and O2 produced. The mass of carbon and hydrogen in the CO2 and H2O is equal to mass of carbon and hydrogen in the initial sample Once the masses of all the constituent elements in the original compound have been determined, the empirical formula can be found
