1. J Unit 3 Chemical Reactions 3.5 What is a mole? February 14, 2010 Do Now: Balance equations if needed. Explain why the following reaction will or Will not take place. __ Zn + __ CuSO 4  __ Cu + __ ZnSO 4 AIM : How can we calculate number of moles of a particular substance? The reaction will take place since Zn is Located above Cu on the Activity Series.

2. WHAT IS A MOLE? A MOLE is a unit of measurement for the amount of substance A MOLE = 6.023 x 10 23 atoms How much does it weigh? 1 mole of a substance equals to the molecular mass (or atomic mass) of that substance Avogadro’s Number

3. STEPSEXAMPLE: CARBON HOW TO FIND HOW MUCH A MOLE OF A SUBSTANCE WEIGHTS? 1. Find the atomic mass of an element (C)  12.01amu 2. The atomic mass (but in grams!) is the mass of 1 MOLE of that Element. (C)  12.01amu 1 MOLE  12.01g 3. If more than one element, the MOLECULAR MASS (but in grams) is the mass of 1 MOLE of that substance. O 2  15.99 x 2 ~ 32 O 2  32amu  32g

4. LET’S TRY SOME 2. What is one mole of HCl? H  1amu HCl  1 + 17 = 18amu  18g Cl  17amu

5. HOW TO CALCULATE TOTAL NUMBER OF MOLES? REMEMBER: gram-formula mass = molecular mass in grams

6. CONVERTING GRAMS TO MOLES STEPSEXAMPLE: How many moles are equivalent to 4.75g of sodium hydroxide (NaOH)? 1.Calculate the gram formula mass of the substance (Na)  (O)  (H)  23amu 16amu 1amu  23g  16g 1g1g  40g 2. Plug into equation and solve for number of moles (divide mass by gram-formula mass) Moles = given mass (g) Gram-formula mass Moles = 4.75g 40g Moles = 0.11875 mol

7. CONVERTING MOLES TO GRAMS STEPSEXAMPLE: How many grams are present in 4.05mol of sulfuric acid (H 2 SO 4 )? 1.Calculate the gram formula mass of the substance (H)  (S)  (O)  2amu 32amu 84amu 2g2g  32g  84g  118g 2. Plug into equation and solve for mass (Multiply moles by gram formulas mass) Moles = given mass (g) Gram-formula mass 4.05mol = given mass 118g Given mass = 40.5 x 118 = 477.9g

8. Complete the Independent Practice -IP will be collected at the end of class!!! -WORK ON UNIT 1 IN THE HOMEOWORK PACKET -Make up LABS!! Come see me if you are missing any -Work on 3.4 Independent Practice from Wednesday…..