A hydrocarbon contains C, H, and F atoms. A 5.43 g sample of this hydrocarbon was analyzed and the mass of 2.35 g of carbon and 0.294 g of hydrogen. The molar mass of this compound was measured between 219-225 g/mol, what is the molecular formula of the hydrocarbon that contains C, H and F?

C8H12F6

Explanation:

To solve this question we need to find the moles of each atom in order to find the empirical formula (The empirical formula is defined as the simplest whole-number ratio of atoms present in a molecule). Using the empirical formula and the molar mass we can find molecular formula as follows:

Moles C:

2.35g * (1mol / 12g) = 0.1958 moles C

Moles H:

0.294g (1mol /1g) = 0.294 moles H

Moles F -Molar mass: 19.0g/mol-:

Mass F: 5.43g - 2.35g C - 0.294g H = 2.786g F * (1mol / 19.0g) = 0.1466 moles F

The moles of atoms dividing in the moles of F (Lower number of moles) produce the simplest ratio as follows:

C = 0.1958mol C / 0.1466mol F = 1.33

H =0.294mol H / 0.1466mol F = 2

F = 0.1466 mol F / 0.1466mol F = 1

As the empirical formula requires whole numbers, this ratio multiplied 3 times:

C = 4

H = 6

F=3

The empirical formula is:

C4H6F3

With molar mass of:

4C = 12*4 = 48

6H = 1*6 = 6

3F = 19*3 = 57

The molar mass is: 48g/mol + 6g/mol + 57g/mol = 111g/mol

As we know the molecule has a molar mass between 219-225g/mol and the empirical formula is 111g/mol, 2 times empirical formula will produce a molecule with the molar mass of the molecule, that is:

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.

i think tornado but not 100%