If you use an IR spectra you can determine the functional groupd of the compound,(hydroxyl, ester, ketones, etc.)After which, using the NMR spectra you can determine the strcuture of the hydrocarbon part of the compound (whether rings, double bonds, etc.)
It's very easy. First of all we test the given sample in laboratory to know about its constitution. Let's discuss it by taking an example:-
Suppose the constitution of a compound is given as below:-
C = 92.4%, H = 7.6%
let's assume that the sample is 100 gram. so the weight of carbon is 92.4 gram & that of hydrogen is 7.6 gram. Now it's we must make sure that is the total of weights of constituents 100 or not? If it is not 100, it means there is an another element in the compound, and this is always oxygen in case of hydrocarbons.
Step 1st :- Find out the number of moles of each element
number of moles = weight of the element/Atomic Mass
number of moles of C = 92.4/12 = 7.7 moles
number of moles of H = 7.6/1 = 7.6 mole
Step 2nd:- Find out the relative ratio of the moles:- It is simply done by dividing all by the smallest one
C = 7.7/7.6 = 1.01
H = 7.6/7.6 = 1
Step 3rd:- If the ratio is not whole numbers the multiply all the numbers by a smallest integer number to make them whole numbers.
Here in this case both are nearly whole numbers. so there is need to multiply these numbers.
C = 1
H = 1
Step 4th:- Write the empirical formula
C1H1
step 5th:- Find the weight of empirical formula
1*12 + 1*1 = 13
now if the molecular weight is given then the molecular formula can be written easily.
molecular weight = ( empirical formula weight)n
for example the molecular weight is 78.
n = 78/13 = 6
so the molecular formula is = C6H6
in formula mass look at your Periodic Table and find the elements from you compound.
in ex: H20 ----- it has two H and one O
1 element H has 1g x 2 = 2g
1 element o has 16 g x 1 = 16g
add them up = 18g all together
there is 2g of H and 18g of O in one compound of H2O
Just dont over think it man, Im sure you`ll do fine
***The formula mass of a compound or element is the sum of the atomic masses given in the formula of the substance per the Periodic Table (An Introduction to Physical Science, 12th Edition, bu Shippman, Wilson, .and Todd)
Find the mass of each atom within the compound and multiply this by their subscript. Do this for each atom and add them together at the end to get the total mass of the compound.
Example: H2SO4
mass H= 1.01g
mass S= 32g
mass O= 16g
Total mass = 2(H) + S + 4(O) = 98.02g
By knowing its valency
The molecular formula of a compound can not be determined solely based on its molar mass. In this case, without additional information, it is not possible to determine the molecular formula of the compound CH2.
C6h12o6
((mass of element)/(mass of compound))*100
The formula mass for boron nitrate is 197 grams per mole.
the empirical formula and the molar mass
The molecular formula of a compound can not be determined solely based on its molar mass. In this case, without additional information, it is not possible to determine the molecular formula of the compound CH2.
It is called the molar mass of that compound. In other words, the total mass of all of the elements in a compound is equal to one mole of that compound.
The formula of the compound and the Atomic Mass of its elements.
A sample of a compound contain 1.52 g of Nitrogen and 3.47 g of Oxygen. The molar mass of this compound is between 90 grams and 95 grams. The molecular formula and the accurate molar mass would be N14O35.
Mass percentage calculations determine the percentage of an element based on mass in a compound. This can then be used to determine the percentage in a compound of each individual element.
t
C6h12o6
The mass of a mole of an ionic compound.
((mass of element)/(mass of compound))*100
The formula mass for boron nitrate is 197 grams per mole.
titin C169723H27646
formula mass