Chemical analysis of an organic compound found the following composition: 40.0% C, 53.5% O, and 6.7% H. If the molar mass is 180.2 g/mol, how many empirical formula units are there in the molecular formula?

To form the molecular formula, we need 6 units of empirical formula

Explanation:

We are given:

Percentage of C = 40.0 %

Percentage of O = 53.5 %

Percentage of H = 6.7 %

Let the mass of compound be 100 g. So, percentages given are taken as mass.

Mass of C = 40 g

Mass of O = 53.5 g

Mass of H = 6.7 g

To formulate the empirical formula, we need to follow some steps:

Moles of Carbon =

Moles of Hydrogen =

Moles of Oxygen =

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 3.33 moles.

For Carbon =

For Hydrogen =

For Oxygen =

The ratio of C : H : O = 1 : 2 : 1

The empirical formula for the given compound is

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

We are given:

Mass of molecular formula = 180.2 g/mol

Mass of empirical formula = 30 g/mol

Putting values in above equation, we get:

Multiplying this valency by the subscript of every element of empirical formula, we get:

Or,

Hence, to form the molecular formula, we need 6 units of empirical formula

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.