A molecular compound contains 92.3 % carbon and 7.7 % hydrogen by mass. If 0.142 mol of the compound weighs 11.08 g, what is its molecular formula?

The molecular formula of the compound is C6H6

Explanation:

Step 1: Data given

Assume the mas = 100 grams

The compound contains:

92.3 % C = 92.3 grams C

7.7 % H = 7.7 grams

Step 2: Calculate moles

Moles = mass / molar mass

Moles C = 92.3 grams / 12.01 g/mol

Moles C = 7.685 moles

Moles H = 7.7 grams / 1.01 g/mol

Moles H = 7.62 moles

Step 3: Calculate mol ratio

We divide by the smallest amount of moles

C: 7.685 /7.62 = 1

H: 7.62 / 7.62 = 1

The empirical formula = CH

This formula has a molecular mass of 13.02 g/mol

Step 4: Calculate molecular mass

Molar mass = mass / moles

Molar mass = 11.08 grams / 0.142 moles

Molar mass = 78.02 g/mol

Step  5: Calculate molecular formula

For the molecular formula, we need the molecular weight:

78.02 / 13.02 = 6

We have to multiply the empirical formula by 6

6*CH = C6H6

The molecular formula of the compound is C6H6

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).

the answer for sodium is 0.186

the answer for rubidium is 0.251