1. The Mole Mole Calculations

2. Molar Mass mass of one mole of a substance units: grams/mole equal to the ATOMIC MASS of the element, rounded to two numbers after the decimal point for compounds, equal to the SUM of the masses of all the elements in the compound (multiply each elements’ atomic mass by the subscript)

3. Molar Mass What is the molar mass of Aluminum (Al)? – Look at the PT the atomic mass for Al is 26.9815385 Round this to two digits after the decimal 26.98 – The unit for molar mass is g/mol Al = 26.98 g/mol What is the molar mass of NaCl? – Look up the mass of every element in the compound and add them together. Round the masses before you add! Na = 22.99 g/mol Cl = 35.45 g/mol NaCl = 58.44 g/mol

4. What is the molar mass of H 2 O – Find the masses of each element (round) H = 1.01 g/mol O = 16.00 g/mol – Since there are 2 Hydrogen atoms multiply the mass of Hydrogen by 2. 1.01 x 2 = 2.02 – Add that mass to the Oxygen to get your total 2.02 + 16.00 = 18.02 g/mol

5. What is the molar mass of Ca (NO 3 ) 2 ? – Subscripts outside a parenthesis will distribute to all elements inside the parenthesis. It will not multiply elements outside the parenthesis N 2 O 6 Ca 2 – Multiple the subscripts by the masses on the PT 14.01 x 2 = 28.02 16.00 x 6 = 96.00 40.01 x 1 = 40.01 164.03 g/mol

6. Molar Mass Cont… 1 mole of X = atomic mass of X (grams) 1 mole of X = 22.4 L of X (only if a gas at STP) 1 mole X = 6.022 x 10 23 particles of X (atoms, molecules, or ions) NEVER put 6.022 x 10 23 in front of the unit GRAMS

7. Particles Atoms, molecules, ions Mass grams or Kg Volume Liters of a gas at STP 1 mole = 6.022 x 10 23 particles 1 mole = 22.4 Liters1 mole = _____ grams Molar Mass

8. How many moles are in 1 1. 9 g r a m s A u ? 1.Look at the Mole Chart and determine what conversion factor to use. 2.Find the molar mass off the periodic table if you have a mass (We do) 3.Make a railroad 4.Put the Given in the upper left 5.Add the Conversion Factor ( ___ grams = 1 mole) 6.Do the Math. Round to proper sig digs and add the unit

9. The problem talks about Mass. Look at the mole chart … 1 mole = _____ grams. Use the periodic table to find the mass of Au. (196.96 g/mol) 11.9 grams of Au1 mole of Au = 0.0604 196.96 grams of Au Add given and conversion factor to solve. ANSWER: 0.0604183  6.04 x 10 -2 moles of Au Mass (g or Kg) Mass (g or Kg)

10. Example # 2... What is the mass of 3.60 moles of Cu? 1.Find the molar mass of the substance. (63.55 g/mol) 2.Make a railroad. 1.Add the GIVEN 1.Plug in the conversion factor 2.Do the Math

11. 3.60 moles Cu 63.55 grams of Cu 1 mole of Cu Answer: 228.78 grams round to proper sig digs 229 grams of Cu

12. How many molecules are in 2.5 moles of H 2 O ? The problem talks about Molecules. Look at the mole chart … 1 mole = 6.022 x 10 23 particles 2.5 moles H 2 O 6.022 x 10 23 particles H 2 0 1 mole of H 2 O Molecules are a type of particle so they are interchangeable ANSWER: 1.5055 x 10 24 1.5 x 10 24 molecules H 2 O Particles (atom, molecule) Particles (atom, molecule)

13. How many moles are in 10.0 Liters of CO 2 gas at STP? The problem talks about Liters. Look at the mole chart … 1 mole = 22.4 Liters 10.0 Liters of CO 2 1 mole of CO 2 22.4 Liters of CO 2 ANSWER: 0.446428  0.446 Liters of CO 2 Volume (mL or L) Volume (mL or L)