Empirical Formulas and Molar Mass

The video tutorial explains how to determine the empirical formula of ethyl fluoride. It starts by assuming a 100g sample of the compound, converting mass percentages to grams, and then converting these grams to moles using conversion factors. The tutorial then demonstrates how to calculate the ratios of the elements by dividing by the smallest number of moles. Finally, it uses these ratios to determine the empirical formula, showing that for every mole of fluorine, there are two moles of carbon and five moles of hydrogen.

What is the first step in solving the empirical formula problem for ethyl fluoride?

• Calculate the molecular formula

• Assume 100 grams of the compound

• Find the molar mass of each element

• Convert grams to moles

If ethyl fluoride contains 49.97% carbon by mass, how many grams of carbon are there in 100 grams of the compound?

• 39.52 grams

• 10.51 grams

• 49.97 grams

• 100 grams

How many moles of carbon are present in 49.97 grams of carbon?

• 4.164 moles

• 12 moles

• 2.08 moles

• 10.51 moles

What is the molar mass of hydrogen used in the conversion from grams to moles?

• 2 grams/mole

• 19 grams/mole

• 12 grams/mole

• 1 gram/mole

Which element has the smallest number of moles calculated in the problem?

• Fluorine

• Oxygen

• Hydrogen

• Carbon

What is the mole ratio of carbon to fluorine in the empirical formula?

• 1:1

• 2:1

• 5:1

• 1:2

How many moles of hydrogen are there for every mole of fluorine in the empirical formula?

• 10 moles

• 5 moles

• 2 moles

• 1 mole

Why is it important to convert from grams to moles in this problem?

• To find the molecular formula

• To determine the empirical formula ratios

• To calculate the mass percentage

• To identify the elements present

What does the empirical formula of a compound represent?

• The exact number of atoms in a molecule

• The simplest whole-number ratio of atoms

• The total mass of the compound

• The percentage composition by mass

Based on the calculated ratios, what is the empirical formula of ethyl fluoride?

• CH3F

• C2H5F

• C2HF5

• CHF