Molar Mass and Hydrocarbon Formulas

The video tutorial explains how to determine the molecular formula of a hydrocarbon using empirical and molecular formulas. It starts by listing the known data, including pressure, volume, and temperature, and converts the temperature to Kelvin. The ideal gas law is applied to find the number of moles. The molar mass is calculated using the mass and moles of the hydrocarbon. The empirical formula is determined by converting the carbon to hydrogen ratio into moles, resulting in the empirical formula C7H8, which matches the molecular formula. The video concludes with a call to action to subscribe and support the channel.

What is the mass of carbon per gram of hydrogen in the given hydrocarbon?

• 5.5 grams

• 10.5 grams

• 15.5 grams

• 20.5 grams

Which law is used to calculate the number of moles of the hydrocarbon vapor?

• Boyle's Law

• Charles's Law

• Ideal Gas Law

• Avogadro's Law

What is the value of the gas constant R used in the ideal gas law calculations?

• 0.082 J per mole Kelvin

• 1.987 cal per mole Kelvin

• 8.314 J per mole Kelvin

• 0.082 liters atmospheres per mole Kelvin

How many moles of the hydrocarbon are present in the sample?

• 0.030 moles

• 0.015 moles

• 0.045 moles

• 0.060 moles

What is the molar mass of the unknown hydrocarbon?

• 92.1 grams per mole

• 82.1 grams per mole

• 102.1 grams per mole

• 112.1 grams per mole

What is the molar mass of carbon used in the calculations?

• 16 grams per mole

• 14 grams per mole

• 12 grams per mole

• 10 grams per mole

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

• 7:8

• 8:7

• 1:2

• 1:1

What is the empirical formula of the hydrocarbon?

• C9H12

• C6H6

• C7H8

• C8H10

What is the molecular formula of the hydrocarbon?

• C8H10

• C7H8

• C9H12

• C6H6

What is the final conclusion about the empirical and molecular formulas?

• They are irrelevant.

• They are the same.

• They are different.

• They cannot be determined.