chapter 3 calculations etc

Question 1

what is the main focus of organic chem?

Answer 1

The main element that is the focus of organic

chemistry is carbon

Question 2

what are organic compounds made of?

Answer 2

Organic compounds are mainly made of C and
H, sometimes with O, N, P, S, halogens, and
trace amounts of other elements

Question 3

what is the difference between organic and inorganic chem?

Answer 3

The difference between organic chemistry and
inorganic chemistry is an organizational
one…not a fundamental one.

Question 4

types of hydro carbons

Answer 4

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

Question 5

how are organic molecules drawn?

Answer 5

displayed or skeletal formula or 3D arrangement

Question 6

describe displayed formula

Answer 6

Shows location of all atoms, including the hydrogens

Question 7

describe skeletal formula

Answer 7

“Hydrogens attached to the carbon are removed, lines
represent bonds and when two lines meet we assume it
to be a carbon atom

Question 8

describe 3D arrangement

Answer 8

Show arrangement of bonds in space

Question 9

what are functional groups used for

Answer 9

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

Question 10

know functional groups in chart (make cards of later)

Answer 10

ok

Question 11

molar mass

Answer 11

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

Question 12

what is formula mass

Answer 12

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

Question 13

how can molar mass be used as a conversion factor

Answer 13

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

Question 14

what is percent composition related to?

Answer 14

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

Question 15

what is percent composition NOT?

Answer 15

• 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)

Question 16

percent comp formula

Answer 16

Mass % of element X = mass of element X in 1 mol of compound/molar mass of compound x 100

Question 17

what happens if you have 100g of sample?

Answer 17

the %X directly converts in to mass quantity

Question 18

how can chemical formulas be used as conversion factors?

ex in notes

Answer 18

Chemical formulas have inherent relationships between

numbers or moles of atoms and molecules

Question 19

what can chemical formulas be used to convert?

Answer 19

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!

Question 20

how is an empirical formula found from data? steps?

Answer 20

1. 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
2. Convert grams to moles
   a)use molar mass of each element
3. Write a pseudoformula using moles as subscripts
4. Divide all by smallest number of moles
   a) if result is within 0.1 of whole number, round to whole
   number
5. 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

Question 21

how is n calculated with empirical formula?

Answer 21

n= molecular formula molar mass / empirical molar mass

Question 22

what is combustion analysis?

Answer 22

• 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

Question 23

what happens after combustion analysis?

Answer 23

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

Question 24

process of combustion analysis

Answer 24

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