Question

Below, make sure to SHOW ALL WORK to receive credit. If only an answer is provided you will receive a 0/10.Part 1You need to find the empirical formula of a compound. This compound has 54.2 g of O, 40.6 g of C and the tiny amount of 5.1 g of H. Part 2Based on the empirical formula you found above, what is the molecular formula if the molar mass of the whole compound is 118.084 grams per mole?

Answer 1

To calulate the empirical formula we have to divide the mass of each component by its atomic mass, let's write down the atomic mass of each component:

Mm of O = 16 g/mol; Mm of C = 12 g/mol and Mm of H = 1 g/mol

Now we divide the measured mass of each component by its atomica mass so we can obtain a relative number of moles:

Oxygen:

`n\text{ of O = }\frac{54.2\text{ g of O}}{32\text{ g/mol}}=3.38\text{ mol of O}`

Carbon:

`n\text{ of C = }\frac{40.6\text{ g of C}}{12\text{ g/mol}}=3.38\text{ mol}`

Hydrogen

`n\text{ of H = }\frac{5.1\text{ g of H}}{1g/mol}=5.1\text{ mol}`

Now we divide each value by the lower number obtained in this calculation (this calculation is called normalization) in this case both C and O are both the lower number 3.38 mol:

Oxigen:

`relative\text{ number of atoms of O= }\frac{3.38\text{ mol}}{3.38}=1\text{ mol}`

Carbon:

`relative\text{ number of atoms of C= }\frac{3.38\text{ mol}}{3.38}=1\text{ mol}`

Hydrogen:

`relative\text{ number of atoms of H= }\frac{5.1\text{ mol}}{3.38}=1.5\text{ mol}`

These values are the values of the empirical formula:

`C_1O_1H_(1.5)`

To avoid the use of decimal points in the formula it can also be expresed like:

`C_2O_2H_3`

Part 2

The empirical equation gives the proportion of the atoms pressnt in the molecule but do not give the actual number of atoms of each component. To calculate the actual number of atoms we calculate the molar mass of the empirical equation by adding mass all the atoms:

Mm empirical = 2X12 + 2X16+3x1 = 59 g/mol

Now we divide the real molar mas by the empirical molar mass:

`(118.084g/mol)/(59g/mol)=2`

this is the number of times that the empirical molecule is repited in the real molecule so the real molecule is:

`C_4O_4H_6`