1. Mountains into Molehills
Mass-Mole Conversions

2. Chem Catalyst
Arsenic, As, arsenic (III) oxide, As2O3, and arsenic (III) sulfide, As2S3, are all toxic because they contain arsenic.
Which is more toxic, 1 mol of As or 1 mol of As2O3? Explain your thinking.
Which is more toxic, 1 g of As2O3 or 1 g of As2S3? Explain.

3. Activity Tape the questions to your left-hand page
Answer the questions on the right-hand page.
Tape tables onto the right hand page in the appropriate place in the question sequence.

4. Homework Toxins Lesson 11: Mountains into Molehills Pages 392-394
Questions 3-8

5. Discussion
Why is it important to be able to convert back and forth between mass and number of moles?
Using Dimensional Analysis to convert: = =
6.02 x 1023 items
1 mole
1 mole
6.02 x 1023 items
1 mole
X grams
X grams
1 mole

6. Practice Using Dimensional Analysis
How many moles of As in a sample with a mass of 125 g?
What is the mass in grams of 3.0 moles of Mg?
How many moles of CaCl2 are in a sample with a mass of 10g?
What is the mass of a 0.16 mole sample of Cl2?
How many molecules are in moles of H2O?
How many molecules are in a 35 gram sample of H2O?
Pay special attention to number 6 – we don’t have one conversion factor that will get us from grams to molecules. We have to first convert to moles and then to molecules.

7. Gas Molar Volume Can you measure the mass of a gas easily?
What is the volume of one mole of a gas? Check your Lesson 10, What’s in a Mole, table.
Do you think this is always true for every gas?
Standard temperature = 273 degrees Kelvin (what is this in Celsius?)
Standard pressure = 1 atmophere (atm) (= 14.7 lb/in2)
STP = 273 deg K and 1 atm
All gasses occupy 22.4 Liters at STP
Make sure you write down the bottom two bullets from this page in your journal.

8. Gas Conversions
22.4 Liters
1 mole
1 mole
22.4 Liters =
What is the volume of 2.5 moles of oxygen gas (O2) at STP?
How many moles of CH4 gas is in 0.4 Liters at STP?
How many grams of N2 gas is in 6.8 Liters at STP?
Make sure your write down these gas conversions in your journal – they work just like the conversions we wrote down yesterday.

9. The Mole House
In the Mole House, in order to get to any other room, you must pass through the “Moles Room”.
If you are in the mole room, you only need one conversion factor to get to the other rooms. However, if you have grams and you need to get atoms or liters, you have to go through the mole room. You have to first convert to moles before you can convert to the other unit.

10. Sample Problems
On whiteboard