1. Moles & Particles or Volume
Chemistry
Unit 6: Chemical Quantities
Lecture 6.3

2. Objective
Convert a quantity of a chemical between moles and particles or moles and volume

3. Why Worry About Particles and Volume?
Moles and grams are not the only quantities we use to “measure” chemicals.
We also use particles; like atoms, formula units, or molecules
We also use liters to measure the volume of gases. (Equal quantities of all gases occupy the same amount of space under the same pressure and temperature)

4. Let’s Talk About Particles
There are……..
Avogadro’s Number
6.022 x 1023
602,000,000,000,000,000,000,000
particles in ONE (1) MOLE of a substance
These particles could be…
Atoms
Molecules
Formula Units
Representative Particles

5. Particles*: can be atoms, molecules, or formula units
If you know the number of moles, you can determine the number of “particles” in a sample of a substance.
Use the Definition of MOLE Equality:
1 mol = x 1023 “particles*”
Particles*: can be atoms, molecules, or formula units

6. Scientific Notation on Your Calculator
To enter a number like…
6.022 x 1023
Type in 6.022
Push “EXP” or “EE” or “x 10x”
Type 23
Do NOT push “x” then “10” then “23”

7. Let’s Talk About Volume
One mole of any substance in the gas state occupies the same amount of space at the same pressure and temperature
At Standard Temperature and Pressure (STP) we know what this volume is…
1 mol(g) = 22.4 L

8. So…
If you know the number of moles at STP, you can determine the number of Liters a sample of a gas occupies (the volume)
Use the Volume at STP Equality:
1 mol(g) = 22.4 L

9. The only thing required is that one of your units is in MOLES!
So How Do You Do It?
It’s just like any other conversion problem…you need given information and equalities from which to form conversion factors…then you just MULTIPLY!!
The only thing required is that one of your units is in MOLES!

10. Moles & Particles
Write down the given information (in particles* or moles) and put it over “1”
Form a conversion factor from the Mole Definition Equality
Write a multiplication problem that cancels out the given units and let’s you end up with the wanted units
Solve!

11. Let Me See A Moles & Particles Example…
How many moles are in 4.7 x 1030 formula units of NaCl?
4.7 x 1030 units x mol NaCl =
x 1023 units
7.8 x 106 mol NaCl

12. Another Moles & Particles Example
How many formula units are in 3.6 mol of AgNO3
3.6 mol AgNO3 x x 1023 units =
mol AgNO3
2.17 x 1024 units AgNO3

13. Moles & Volume
Write down the given information (in Liters or moles) and put it over “1”
Form a conversion factor from the Volume at STP Equality
Write a multiplication problem that cancels out the given units and let’s you end up with the wanted units
Solve!

14. Let Me See A Moles & Volume Example…
How many moles are in 8.2 L of HCl(g) at STP?
8.2 L HCl(g) x 1 mol HCl(g) = L
0.37 L HCl(g) at STP

15. Another Moles & Volume Example
How many Liters are in 1.9 mol of H2O(g) at STP?
1.9 mol H2O(g) x L =
mol H2O(g)
42.56 L H2O(g) at STP

17. Practice
How many moles of magnesium are in 1.25 x 1023 atoms of magnesium?
How many molecules are in 2.12 mol of propane (C3H8)?
0.21 mol Mg
2.08 x mol Mg
1.40 x atoms of propane
1.28 x 1024 molecules C3H8

18. More Practice
What is the volume, in liters, of 0.60 mol SO2 gas at STP?
How many moles are in L of He gas at STP?
13.44 L SO2(g)
13.44 L SO2
3.93 x mol He
mol He
3.93 x 10-2 mol He

19. Quick Quiz What is a strange property of equal volumes of gases?
What is the Mole equality?
What is the volume at STP equality?
How many moles are in 3.8 x 1024 molecules of HF?
What is the volume in liters of 0.86 mol of HF gas?
Equal quantities of all gases occupy the same amount of space under the same pressure and temperature.
1 mole = x 1023 particles*
1 mole = 22.4 L (at STP)
6.31 molecules HF
19.26 L of HF gas

20. Write your summary and questions now