Drill What is the relationship between particles

and mass in a substance?

Objective

The student will be able to: Use molar mass (formula mass) in order to

calculate % composition.

SAT/HSA Enrichment The number of grams in 1.5 x 1025

molecules of CO2 are

Percent Composition and Chemical Formulas

How much Sugar is in Bubble Gum?

Engagment What is in bubble gum?

Discussion How can we find the amount of sugar in the bubble

gum.

Generate a list of ideas on the board.

Percent Composition and Chemical Formulas

• It helps to know the percents of the components in a shirt because they affect how warm it is, whether it will need to be ironed, and how it should be cleaned. You will learn how the percents of the elements in a compound are important in chemistry.

The Percent Composition of a Compound

The percent by mass of an element in a compound is the number of grams of the element divided by the mass in grams of the compound, multiplied by 100%.

Percent Composition from Mass Data

The relative amounts of the elements in a compound are expressed as the percent composition or the percent by mass of each element in the compound.

Percent Composition from Mass Data

The relative amounts of the elements in a compound are expressed as the percent composition or the percent by mass of each element in the compound.

Percent Composition from the Chemical Formula

Percent Composition as a Conversion Factor You can use percent composition to

calculate the number of grams of any element in a specific mass of a compound.

The Percent Composition of a Compound

Propane (C3H8) is 81.8% carbon and 18% hydrogen. You can calculate the mass of carbon and the mass of hydrogen in an 82.0 g sample of C3H8.

Molecular Formulas

Quick Quiz1. Calculate the percent by mass of carbon in

cadaverine, C5H14N2, a compound present in rotting meat.

a. 67.4% Cb. 58.8% Cc. 51.7% Cd. 68.2% C

Bite the Bubble Purpose:

Determine the percent mass of sugar in bubble gum.

To complete the lab and the problems.Place paper in the bin when finished.

Percent Composition Complete problems 1-2 as class. Work with your partner (person next to

you) to complete problems 3-8. Review answers as a class.

Summary

1. Did we accomplish the objective? Explain.2. Determine the equation used to determine

the percent composition of an element.3. Identify the steps used to determine the

percent composition of an element.4. What does the total percent composition of

a compound equal?5. Summarize the main idea of today’s lesson.

Homework Percent Composition worksheet.