1 Mr. ShieldsRegents Chemistry U04 L03

2 What Are Mole Conversions? We’re now going to look at some useful Relationships (that is conversions). Actually, we’ve already done some of these! Mass # of Particles VolumeMoles

3 Chem Conversions We know 1 mole = x particles This is Avogadro’s number (N A ) We also know 1 mole = 22.4 liters This is the Molar Volume (V m ) We also know that 1 mole = Molar Mass So, “How do we convert from one value to another”?

4 We Use the “Conversion Chart” AKA - The Mole Map

5 Mole Conversions RULE 1: ALL conversions TO MOLES involve DIVISION RULE 2: ALL conversions FROM MOLES to MASS, VOLUME, or # OF PARTICLES involve MULTIPLICATION “Moles leave the mole hole to Multiply” mole hole to Multiply” Mass # of Particles VolumeMoles

6 Converting Moles to Particles (There and back again) Remember 6.02 X = 1 mole of anything Remember 6.02 X = 1 mole of anything Atom, molecules, protons, ions, marbles Take a look at the Mole Map Take a look at the Mole Map –Particles to Moles: (into the mole hole) Divide the # of Particles by x –Moles to Particles: (out of the mole hole) Multiply the # of moles by x 10 23

7 Mole/Particle Conversions 1. How many molecules are there in 4.0 moles of H 2 O 2 ? # of molecules = 4.0 moles x 6.02 x particles 1 mole 1 mole = 24 x = 2.4 x particles = 24 x = 2.4 x particles 2. How many moles are there in 7.14 x molecules? # of moles = 7.14 x particles / 6.02 x particles 1 mole 1 mole = 1.19 moles = 1.19 moles Try this ….

8 Mole/Particle Conversions How many atoms are in 3 moles of sugar (C 12 H 24 O 11 )? 3 moles of sugar X 6.02 X Mole of sugar = X = X molecules of sugar #atoms = 47 x x = 8.49 x How about this one?

9 Mole/Mass Conversions Look at the Conversion Chart Again… –Mass to Moles: Divide mass by molar mass –Moles to Mass: Multiply moles by molar mass Mass # of Particles VolumeMoles

10 Mole/Mass Conversions You’re going to need to use the Periodic Table for any conversion involving mass because we need to 1st calculate Molar mass How many moles of CoCl 2. 6H 2 O are there in 160g? Molar mass = x x x = g/mol # of moles = 160g / g/mol = 0.67 moles (We’re going into the mole hole so we’re going to be dividing)

11 Mole/Mass Conversions How many grams are in moles of CuSO 4 ? (Remember … We’re leaving the mole hole so we’ll be multiplying) First find the molar mass of the CuSO 4 compound. Cu = 63.5 S = O = 64 Molar mass of CuSO 4 = g/mol 0.954mol x g/mol = g Let’s now convert moles to grams …

12 Problems 1. 1.How many atoms are there in 98.5 grams of tin ? 2. How many atoms are there in 20 grams of H 2 0 ? Gram Atomic mass of Tin = grams 98.5/ = 0.83 moles 0.83 moles x x atoms/mole = 5.0 x atoms gram molecular mass of water = 18 grams 20g/18g = 1.11 moles 1.11 moles x x = 6.69 x molecules H x 6.69 x molecules = 2.0 x atoms

13 Problems Here’s another problem: Which sample contains the same number of atoms as 4g of Lithium? 1) 1.16g He 2) 20.18g Ne 3) 17.96g P 4) 10.46g Be ANS: Gram Atomic mass of Li = 6.94 g 4 g/6.94 g = 0.58 moles Atomic Mass He (4.00) Ne (20.18) P (30.97) Be (9.01) Mol of He = 1.16/4 = 0.29 Mol of Ne = 20.18/20.18 = 1 Mol of P = 17.96/30.97 = 0.58 Mol of Be = 10.46/9.01 = 1.16

14 Volume/Mole Conversions OK. Now lets convert between Volume and moles. Look at the Conversion Chart … Volume to Moles: V m = 22.4L / mole at STP Moles to Volume: These calculations are independent of what gas Is involved Ex. NH 3, CO 2, H 2 etc. Multiply mol by molar volume Divide volume by molar volume

15 Volume/Mole Conversion Problem: How many liters are occupied by 3.5mol of NH 3 at STP? 3.5 mol x 22.4L = 78.4L 1 mol 1 mol How many moles are there in 6.5L of N 2 ? How many grams are there? 6.5L / 22.4L =.29 mol 0.29 mol x 28.02g/mol = 8.13g