Empirical Formulas and Percent Composition

The video tutorial explains how to calculate empirical formulas using experimental data, examples, and percent composition. It covers converting masses to moles, writing preliminary formulas, and adjusting ratios to whole numbers. Examples include calculating formulas for carbon and hydrogen, hematite, and a compound from percent composition.

What is the first step in finding an empirical formula from experimental data?

• Balance the chemical equation

• Determine the percent composition

• Write the chemical equation

• Convert masses to moles using molar mass

Why do we divide by the smallest number of moles when adjusting empirical formulas?

• To simplify the calculation

• To balance the equation

• To ensure whole number ratios

• To find the limiting reactant

In the example with carbon and hydrogen, what is the empirical formula derived?

• CH2

• C2H2

• CH

• C2H

What is the molar mass of carbon used in the example calculation?

• 1.008

• 12.011

• 16.000

• 14.007

What is the empirical formula of hematite based on the given masses of iron and oxygen?

• FeO

• FeO2

• Fe3O2

• Fe2O3

Why is it important to maintain the ratio of moles when calculating empirical formulas?

• To find the limiting reactant

• To balance the equation

• To ensure accuracy

• To simplify calculations

In the hematite example, why is it incorrect to round 1.5 to 2?

• It changes the chemical identity

• It does not trust the data

• It simplifies the calculation

• It balances the equation

When calculating empirical formulas from percent composition, what assumption is made about the sample size?

• It is 1 liter

• It is 100 grams

• It is 50 grams

• It is 1 mole

What is the first step when using percent composition to find an empirical formula?

• Convert percent to grams

• Write the chemical equation

• Determine the molar mass

• Balance the equation

In the percent composition example, what is the empirical formula of the gas?

• CO

• CO2

• C3O7

• C2O7