Science Starter (Week 10, Friday, 4/8/16) Grab a calculator! When do you calculate molar mass? What is the molar mass of NO2? How do you tell the difference between one-step and two- step conversions problems? What is the percent of students who passed the quiz yesterday if 12 out of 18 students passed? What about 7 out of 13 students?

Agenda Science Starter Percent Composition Mole Box Project Quiz Return Homework

Weekly Schedule Today: Percent Composition Monday: 1-Step and 2-Step Stoichiometry Tuesday: 3-Step Stoichiometry Wednesday: Limiting Reagents Thursday: Unit 5 Review Friday: Unit 5 Test

Unit 5 Quiz: Molar Conversions 3rd Block 4th Block Mean: 74% Max: 100% Min: 10% Mean: 70% Max: 100% Min: 10%

Unit 5: The Mole Percent Composition

Lab: Percent Composition of Sugar in Gum Date: Purpose: to determine the percent by mass of sugar in gum Hypothesis: Write a hypothesis about how much sugar you think is in gum. Record this, formatted as a hypothesis in complete sentences, in your hypothesis section!

Materials Bubblegum Large zip-loc bag Scale

Mass of Gum and Wrappers Recorded Data Mass of Gum and Wrappers Mass of wrappers Mass of ONLY gum Mass of Bag and Chewed Gum Mass of Bag Mass of ONLY chewed gum Mass of Sugar in gum

Weigh all pieces of gum, still wrapped, together. Record. Procedure Weigh all pieces of gum, still wrapped, together. Record.  Unwrap gum and start chewing. Wrappers must all be massed together to find gum mass. Record mass.  Chew the gum for several minutes until you believe that all of the sugar has been dissolved in your saliva.  Place the chewed gum in bag. Make sure it’s not all slimy!  Mass the bag and the chewed gum. Record the mass of bag and chewed gum in your data table.

Mass of Gum and Wrappers Recorded Data Mass of Gum and Wrappers Mass of wrappers Mass of ONLY gum Mass of Bag and Chewed Gum Mass of Bag Mass of ONLY chewed gum Mass of Sugar in gum

Discussion 1) Calculate the percent sugar in your original sample of Dubble Bubble bubble gum. 2) Do you find this surprising? Why or why not? 3) Find the percent by mass of H in H2O 4) Find the percent by mass of C in C6H12O6

Conclusion Write a step-by-step procedure for finding the percent by mass of a compound

Consensus Percent Composition The percent by mass of each element in the compound. Very simple calculations: Mass of element x 100% = % by mass of element Total mass of compound

Examples What is the percent by mass of oxygen in CaCO3? What is the percent by mass of copper in Cu2S?

What is the percent by mass of nitrogen in Mg(NO3)2?

The Mole Box Project Due Friday, 4/15 Objective: to create a visual representation of THE MOLE Directions: create a mole box that satisfies the following requirements. Your mole box must have a theme! Each side of the box must have the following: Bottom = blank Top = title Title must be something creative involving the mole and relate to your theme Must have a picture of a mole Sides 1 mole = Avogadro’s Number (including #) 1 mole = molar mass This should include 3-4 examples of your favorite elements and/or compounds with their molar mass 1 mole = 22.4 L A mole joke or chemistry joke Make one up! If you can’t think of one…Google will be your best friend here Your entire mole box should be colored/decorated in a way that has to do with your title and theme Extra Credit: answer the following question inside your box or on a separate poster How do we use stoichiometry in real life?

Quiz Return & Today’s Work