Conversion Practice Name ___________________________________ Show all work, round to the nearest hundredth, show proper units Date __________________________ Per ______ HOW TO FIND MOLAR MASS Ex 1: CO2 Steps for finding molar mass: 1. Separate each element from the formula 2. Identify the number of moles per element 3. Multiply the number of moles of each element by their atomic mass from the periodic table 4. Add the numbers and include the unit: g/mol 1_ mol C x 12.01__ g = 12.01 g/mol 2_mol O x 16.00___g = Answer = 32.00 g/mol 44.01 g/mol This is the number of moles for this element Your turn: Calculate the molar mass for the following compounds. Show all work, round all numbers to the nearest hundredth, and include proper units. 1. Ca3N2 2. Al(OH)3 3. Fe2O3 4. H2O HOW TO FIND MOLES WHEN GIVEN GRAMS given grams This is your given grams 1 mole = answer moles (mol) grams (This is molar mass) Ex 2: Calculate the number of moles in 2.5g of CO2. 2.5g of CO2 1 mol = 00000 0.06 mol 44.01 g CO2 g This is the molar mass that was calculated in example 1 5.) Your turn: Calculate the number of moles in 235.00g of Ca3N2 = You get this answer by dividing the top number by the bottom number, so 2.5 divided by 44.01 HOW TO FIND GRAMS/MASS WHEN GIVEN MOLES: This is your given moles given moles grams (again, this is molar mass) = answer grams (g) 1mole Ex 3: How many grams are in 7.25 moles of CO2 ? 7.25 moles of CO2 44.01 g This is the molar mass of CO2 which was calculated in example 1 = 319.07 g You get this answer by multiplying the two numbers that are side by side So 7.25 x 44.01 1 mol 6.) Your turn: How many grams are in 3.12 x 103 moles of Al(OH)3? = HOW TO FIND ATOMS, MOLECULES OR FORMULA UNITS WHEN GIVEN MOLES: Use Avogadro’s number here 6.02 x 1023 particles Given moles = 1 mole Answer in molecules, atoms, or formula units. Depends on what word is used in the question Ex 4: How many molecules are in 14 moles of CO2? 14 moles CO2 6.02 x 1023 molecules 8.43 x 1024 molecules = 1 mol To get the answer, you would have to multiply 14 by 6.02 x 1023 7.) Your turn: How many atoms are in 6.98 x 104 moles of H2O? = HOW TO FIND MOLES WHEN GIVEN ATOMS, MOLECULES OR FORMULA UNITS Given particles 1 mole 6.02 x 10 = answer in moles (mol) 23 particles Ex 5: How many moles are in 3.4 x 1023 atoms CO2? 3.4 x 1023 atoms CO2 1 mole = 0.56 mol 6.02 x 1023 atoms 8.) Your turn: How many moles are in 1.33 x 1039 molecules Fe2O3? = To get the answer, you would have to divide 3.4 x 1023 atoms CO2 by 6.02 x 1023 HOW TO FIND ATOMS, MOLECULES, OR FORMULA UNITS WHEN GIVEN GRAMS/MASS:. Given grams 6.02 x 1023 particles = 1 mole (molar mass) grams 1 mole Answer in molecules, atoms, or formula units. Depends on what word is used in the question Ex 6: How many atoms are in 355 g CO2? 355 g CO2 6.02 x 1023 atoms 1 mole 44.01 g 1 mole = 4.86 x 1024 atoms To get the answer, multiply 355 by 6.02 x 1023 and divide that answer by 44.01 9.) Your turn: How many formula units are in 244.86 g Al(OH)3? = HOW TO FIND GRAMS WHEN GIVEN ATOMS, MOLECULES, OR FORMULA UNITS: given particles 1 mole (molar mass) grams 6.02 x 1023 particles = Answer in grams 1 mole Ex 7: How many grams are in 9.20 x 1027 molecules of CO2? 9.20 x 1027 molecules of CO2 1mole 6.02 x 1023 molecules 44.01 g = 6.73 x 105 g 1 mole 10.) Your turn: How many grams are in 3.38 x 1022 molecules of Fe2O3? =