When do you calculate molar mass What is the molar mass of NO 2 How do you tell the difference between onestep and twostep 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 st ID: 531048
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Science Starter (Week 10, Friday, 4/8/16)
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?
Grab a calculator!Slide2
Agenda
Science StarterPercent CompositionMole Box ProjectQuiz ReturnHomework Slide3
Weekly Schedule
Today: Percent CompositionMonday: 1-Step and 2-Step Stoichiometry Tuesday: 3-Step StoichiometryWednesday: Limiting ReagentsThursday: Unit 5 ReviewFriday: Unit 5 TestSlide4
Unit 5 Quiz: Molar Conversions
3rd BlockMean: 74%Max: 100%Min: 10%4th BlockMean: 70%
Max
:
100%
Min:
10%Slide5
Unit 5: The Mole
Percent Composition Slide6
Lab: Percent Composition of Sugar in Gum
Date:Purpose: to determine the percent by mass of sugar in gumHypothesis: 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! Slide7
Materials
Bubblegum Large zip-loc bag Scale Slide8
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 Slide9
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.Slide10
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 Slide11
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 H2O4) Find the percent by mass of C in C6H12O6Slide12
Conclusion
Write a step-by-step procedure for finding the percent by mass of a compoundSlide13
Consensus
Percent CompositionThe percent by mass of each element in the compound.Very simple calculations: Mass of element x 100% = % by mass of element Total mass of compoundSlide14
Examples
What is the percent by mass of oxygen in CaCO3?What is the percent by mass of copper in Cu2S?Slide15
What is the percent by mass of
nitrogen in Mg(NO3)2?Slide16
The Mole Box Project
Due Friday, 4/15Objective: to create a visual representation of THE MOLEDirections: 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 = blankTop = titleTitle must be something creative involving the mole and relate to your theme Must have a picture of a mole Sides1 mole = Avogadro’s Number (including #)1 mole = molar massThis should include 3-4 examples of your favorite elements and/or compounds with their molar mass 1 mole = 22.4 LA mole joke or chemistry jokeMake 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
?Slide17
Quiz Return & Today’s Work