1. Investigation 2: Weighing Toxins
Lesson 5:
Whack a mole!

2. Admit Slip Take a seat and quiet down for the Pop Quiz.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X

3. Today’s Objectives Students will be able to:
Find the molar mass of an element or compound
Convert a number of moles of a substance into its mass in grams
Convert the mass of a substance into the number of moles.
Find the number of atoms or molecules in a sample, given the mass.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X

4. Agenda
Pop Quiz Admit Slip Quiz Review Exit Slip Product: Pop Quiz, Quiz Review, Exit Slip Homework: Study for Quiz Extra Credit Homework

5. Quiz Review Answers b) 6.02 x 1023 2. The mass of _one mole_
3. a) Mg: g/mol c) CaS: g/mol
b) CO2 : 44 g/mol d) C6H12O6:180 g/mol
4. 4 mol * 18 g/mol = 72 g
mol * 25.8 g/mol = g

6. Classwork Review 152 g / 54.94 g/mol = 2.76 mol
3.7 mol * 25 g/mol = g
170 g / 32 g/mol = mol
600 g / 98 g/mol = mol
2.5 mol * 342 g/mol = g

7. Classwork Review 400 g / 44 g/mol = 9.1 mol He = 4 g/mol
13. a) B c) d) 16
(PO4)2 is 8 O’s * 2 mol =
16 moles of O atoms

8. Classwork Review
g Li mol * 6.02 x 1023 = x 1023 = 1.04 x 1024 atoms C
/ 6.94 g/mol =
1.729 moles
(how many atoms are in 1 mole)

9. Classwork Review 16. 1.3 x 1025 molecules 1.3 x 1025 = 13 x 1024 =
Hey, this kinda looks like the mole number.
Let’s see if we can change it into 1023
1.3 x =
13 x =
130 x 1023
Let’s divide this by the mole number to see how many moles this is!
6.02 x =
21.59 moles = 22 mol B

10. Exit Slip / 28 g/mol = 5 moles
How many N2 molecules are in a 140 g sample?
140 g N2
5 mol * x =
30.1 x =
3.01 x 1024 molecules N2
/ 28 g/mol =
5 moles
(how many atoms are in 1 mole)
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X

11. How are moles used to track chemical changes?
•        Chemists use moles to track atoms and molecules that are going through chemical changes.
•        Moles of atoms and molecules are conserved in a chemical equation.
•        In order to calculate mass from moles: Multiply # of moles by the molar mass.
•        In order to calculate moles from mass: Divide # of grams by the molar mass.
© 2004 Key Curriculum Press.
Unit IV • Investigation II-X