THE MOLE Volume and Particles

Converting one unit to another Using Conversion Factors You can then say that there are 12 eggs dozen You know that there are 12 eggs in one dozen. (12 eggs = 1 dozen) To figure out how many eggs there are in 6 dozen, you would: conversion factor Multiply the known quantity by the conversion factor 6 dozen 12 eggs dozen X = 72 eggs

Important Note When using conversion factors you must set up your calculation so that all of the units cancel out except for those needed in your answer Using our knowledge of eggs from the previous example, let’s figure out how many dozen eggs we have if there are 144 eggs 12 eggs dozen 12 eggs We know that there are: but if we set up our problem using this conversion factor: 144 eggs 12 eggs dozen X we cannot cancel out the units we don’t need To solve this problem, we invert (flip over) the conversion factor 144 eggsX = =12 dozen

MOLE CONVERSIONS There are three major types of mole conversions: Avogadro’s Number (6.02x10 23 ) is the number of particles in one mole of a substance  1 Mole = 6.02x10 23 particles (atoms, molecules, etc.)  1 Mole = 22.4 L of gas at STP (standard temp & press)  1 Mole = molar mass (formula mass) in grams

Using a conversion factor to convert moles to particles You know that: 1 mol = 6.02 X particles How many particles are there in 3.50 mol of sucrose ? 1) Set up the conversion factor (remember that the units that will cancel out must be on the bottom). The particle for sucrose is the molecule so: 6.02 X molecules 1 mol sucrose 2) Use your conversion factor to carry out the calculation 3.50 mol sucroseX 6.02 X molecules 1 mol sucrose = 2.11 X molecules Click for help on multiplying and dividing with scientific notation

Practice 1) Zinc (Zn) is a metallic element. Determine the number of atoms (particles) in 2.50 mol of Zn. Remember: 1 mol = 6.02 X atoms (particles) 2.50 mol ZnX 6.02 X atoms Zn 1 mol Zn = 1.51 X atoms Zn 2) How many molecules (particles) are in 11.5 mol H 2 O? 3) How many formula units (particles) are there in 3.25 mol AgNO 3 ? 6.92 X molecules H 2 O 1.96 X formula units of AgNO 3

Using a conversion factor to convert particles to moles We have examined how to convert moles to particles using the conversion factor: 6.02 X particles 1 mol What conversion factor would we use to convert particles to moles? 1 mol 6.02 X particles

How many moles of Aluminum (Al) are there if you have 5.75 X atoms of Al? 5.75 X atoms AlX 1 mol Al 6.02 X atoms Al = 5.75 X mol Al 6.02 X =9.55 mol Al

Convert Moles to Liters WHAT IS THE VOLUME OF 6 MOLES OF HELIUM?

Converts Liters to Moles HOW MANY MOLES ARE THERE IN 50 L OF He?

Multiplying and Dividing Numbers in Scientific Notation Multiplying: multiply the numbers in front of the exponent 4 X 2 = 8 add the exponents = (4 X ) X (2 X 10 5 ) so (4 X ) X (2 X 10 5 ) = 8 X Dividing: 4 X X 10 5 Divide the numbers in front of the exponent 4 / 2 = 2 subtract the exponents – 10 5 = so = 2 X X X 10 5 Return