
George A. answered 04/22/15
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Detail oriented, patient tutor in math, chermistry , programming
a) Molar mass:
9 C 9* 12.01 = 108.09
9 H 9* 1.008= 9.072
4 O 4* 16.00= 64.0
-------
181.16
b) Notes:
First npte:
C9H9O4 + O2 -> CO2 + H2O
We have odd number of H (9) so we will need to double it to form whole H2O.
We have to double the equation:
2C9H9O4 + O2 --> CO2 + H2O
Next we now know the number of CO2 formed. We also know the number of H that forms water.
2C9H9O4 + O2 -> 18CO2 + 9H2O
Note that on the right we need 45 O atom, which is an odd number, while on the left we have even number of O atoms, including the C9H9O4. Therefore we will need to double the equation again, to have even number of O atoms on the right.
4C9H9O4 + O2 --> 36 CO2 + 18H2O
Now we can calculate the number of O2 we need on the left: On the right we have 72 + 18 'O' atoms, a total of 90.
On the left we have 16 'O" atoms from the organic compound so we subtract this number from the needed 90: 90 - 16 = 74. We divide 74 by 2 to calculate the O2 molecules, which is 37. The balanced equation is:
4 C9H904 +37 O2 -> 36 CO2 + 18 H2O
Note that all the atoms must be balanced on both side of the equation:
left right
C 36 36
H 36 36
O 90 90
c) In saturated organic compounds the formula is CnH2n+2 where n can be any number.
The presents of Oxygen does not change this formula: CnH2n+2Ox where n is as above and x can be any number (within reason x < n ) So for a 9 carbon compound we should have 20 hydrogens. When we introduce "unsaturation" - a double or triple bond we take away a pair of hydrogens for each ( 2 for a double and 4 for a triple bond). Similarly if it is a cyclical compound we take away two hydrogens for the unsaturation. Thus C9H9O4 must be a cation, with one hydrogen missing.
One can draw a large number of isomers for this formula(too many for me) with 6 "unsaturation", including several heterocyclical compounds, ethers, ketones, acid groups. Some of these compounds may have chiral carbons.
I hope this helps.