What the mole?!? You dont scare me, Chapter 11!

For each question asked: Copy question (These are on the blog if you arent fast enough in class.) Copy question (These are on the blog if you arent fast enough in class.) Determine which type of problem is being asked Determine which type of problem is being asked Set up problem (Solving is for homework.) Set up problem (Solving is for homework.)

#1 How many molecules are collected in 6.50 moles of CuCl 2 ? How many molecules are collected in 6.50 moles of CuCl 2 ?

# g of bismuth represents how many atoms of bismuth? g of bismuth represents how many atoms of bismuth?

#3 What is the molar mass of chlorine gas? What is the molar mass of chlorine gas? Be careful of the formula!! Be careful of the formula!!

#4 Dr. Bubba (chemist extraordinaire) wants to use.450 mol of aluminum sulfide. How much should be measured onto the balance? Dr. Bubba (chemist extraordinaire) wants to use.450 mol of aluminum sulfide. How much should be measured onto the balance?

#5 A compound has a molar mass of 110.1g/mol. Its percent composition seems to indicate an empirical formula of C 3 H 3 O. A compound has a molar mass of 110.1g/mol. Its percent composition seems to indicate an empirical formula of C 3 H 3 O. Is that the correct formula for the compound? Is that the correct formula for the compound?

#6 What percent of gypsum is actually calcium? What percent of gypsum is actually calcium? (gypsum = CaSO 4 · 2H 2 O) (gypsum = CaSO 4 · 2H 2 O)

#7 What percent of gypsum is actually water? What percent of gypsum is actually water?

#8 How many moles of iron (III) nitrate are represented by 43.56mg of the salt? How many moles of iron (III) nitrate are represented by 43.56mg of the salt? (Hey! Is that a milligram?) (Hey! Is that a milligram?)

#9 What is the average mass of 50 atoms of sulfur? What is the average mass of 50 atoms of sulfur?

#10 Styrene is 92.25% carbon and 7.75% hydrogen. What empirical formula does that indicate? Styrene is 92.25% carbon and 7.75% hydrogen. What empirical formula does that indicate?

#11 The molar mass of styrene is 104g/mol. What must be the molecular formula? The molar mass of styrene is 104g/mol. What must be the molecular formula? (Yep, use #10 to figure this out.) (Yep, use #10 to figure this out.)

#12 How many molecules of CO 2 are in 44.10g of carbon dioxide? How many molecules of CO 2 are in 44.10g of carbon dioxide?

#13 What percent of anhydrous copper (II) sulfate is oxygen? What percent of anhydrous copper (II) sulfate is oxygen?

#14 What is the empirical formula of a compound containing: What is the empirical formula of a compound containing: 10.52g nickel 10.52g nickel 4.38g carbon 4.38g carbon 5.10g nitrogen 5.10g nitrogen

#15 One billion molecules of water are in your hand; how many moles of molecules are you holding? One billion molecules of water are in your hand; how many moles of molecules are you holding?

Fine So, how did you do? So, how did you do? Post a comment for bonus points! (Shhhh, its our secret!!) Post a comment for bonus points! (Shhhh, its our secret!!) Valid only for 2/19/10…… Valid only for 2/19/10……

#1 How many molecules are collected in 6.50 moles of CuCl 2 ? How many molecules are collected in 6.50 moles of CuCl 2 ? 6.50mol CuCl 2 (6.022 x molecules) 6.50mol CuCl 2 (6.022 x molecules) ( 1 mole CuCl 2 ) ( 1 mole CuCl 2 ) 3.91 x molecules CuCl x molecules CuCl 2

# g of bismuth represents how many atoms of bismuth? g of bismuth represents how many atoms of bismuth? g (6.022 x atoms Bi) g (6.022 x atoms Bi) ( g Bi) ( g Bi) x atoms of Bi x atoms of Bi

#3 What is the molar mass of chlorine gas? What is the molar mass of chlorine gas? Be careful of the formula!! Chlorine is Cl 2 !! Be careful of the formula!! Chlorine is Cl 2 !! 2(35.453g/mol) = g/mol Cl 2 2(35.453g/mol) = g/mol Cl 2

#4 Dr. Bubba (chemist extraordinaire) wants to use.450 mol of aluminum sulfide. How much should be measured onto the balance? Dr. Bubba (chemist extraordinaire) wants to use.450 mol of aluminum sulfide. How much should be measured onto the balance? 0.450mol Al 2 S 3 ( g Al 2 S 3 ) 0.450mol Al 2 S 3 ( g Al 2 S 3 ) (1 mol Al 2 S 3 ) (1 mol Al 2 S 3 ) 67.6 g Al 2 S g Al 2 S 3

#5 A compound has a molar mass of 110.1g/mol. Its percent composition seems to indicate an empirical formula of C 3 H 3 O. A compound has a molar mass of 110.1g/mol. Its percent composition seems to indicate an empirical formula of C 3 H 3 O. Is that the correct formula for the compound? Is that the correct formula for the compound? C 3 H 3 O = g/mol which is only half of the required 110.1g/mol C 3 H 3 O = g/mol which is only half of the required 110.1g/mol No, C 6 H 6 O 2 is the correct molecular formula. No, C 6 H 6 O 2 is the correct molecular formula.

#6 What percent of gypsum is actually calcium? What percent of gypsum is actually calcium? (gypsum = CaSO 4 · 2H 2 O) (gypsum = CaSO 4 · 2H 2 O) Ca x 100 Ca x 100 CaSO 4 ·2H 2 O CaSO 4 ·2H 2 O 40.08/172.18x100 = 23.28% Ca 40.08/172.18x100 = 23.28% Ca

#7 What percent of gypsum is actually water? What percent of gypsum is actually water? 2H 2 O x 100 2H 2 O x 100 CaSO 4 ·2H 2 O CaSO 4 ·2H 2 O /172.18x100 = % H 2 O /172.18x100 = % H 2 O

#8 How many moles of iron (III) nitrate are represented by 43.56mg of the salt? How many moles of iron (III) nitrate are represented by 43.56mg of the salt? (Hey! Is that a milligram?) (Hey! Is that a milligram?) 43.56mg Fe(NO 3 ) 3 (10 -3 g) (1 mole) = 43.56mg Fe(NO 3 ) 3 (10 -3 g) (1 mole) = (1 mg) ( g) (1 mg) ( g) x moles Fe(NO 3 ) x moles Fe(NO 3 ) 3

#9 What is the average mass of 50 atoms of sulfur? What is the average mass of 50 atoms of sulfur? 50 atoms S ( g S) = 50 atoms S ( g S) = (6.022 x atoms S) (6.022 x atoms S) x g S (Note: 4 sig figs) x g S (Note: 4 sig figs) (Note: the smallest mass unit we saw was the attogram which is ) (Note: the smallest mass unit we saw was the attogram which is )

#10 Styrene is 92.25% carbon and 7.75% hydrogen. What empirical formula does that indicate? Styrene is 92.25% carbon and 7.75% hydrogen. What empirical formula does that indicate? CH CH

#11 The molar mass of styrene is 104g/mol. What must be the molecular formula? The molar mass of styrene is 104g/mol. What must be the molecular formula? (Yep, use #10 to figure this out.) (Yep, use #10 to figure this out.) CH = g/mol AND 104/13 = 8 CH = g/mol AND 104/13 = 8 Therefore, styrene is C 8 H 8 Therefore, styrene is C 8 H 8

#12 How many molecules of CO 2 are in 44.10g of carbon dioxide? How many molecules of CO 2 are in 44.10g of carbon dioxide? x molecules CO x molecules CO 2 The mass given happens to be the molar mass which IS the mass of Avogadros number for CO 2 This one of those that if you recognize that number as its molar mass, you dont even have to calculate. The mass given happens to be the molar mass which IS the mass of Avogadros number for CO 2 This one of those that if you recognize that number as its molar mass, you dont even have to calculate.

#13 What percent of anhydrous copper (II) sulfate is oxygen? What percent of anhydrous copper (II) sulfate is oxygen? 4O/CuSO 4 x 100 4O/CuSO 4 x % oxygen % oxygen

#14 What is the empirical formula of a compound containing: What is the empirical formula of a compound containing: 10.52g nickel 10.52g nickel 4.38g carbon 4.38g carbon 5.10g nitrogen 5.10g nitrogen Ni(CN) 2 nickel (II) cyanide Ni(CN) 2 nickel (II) cyanide Most of you would have CORRECTLY put NiC 2 N 2 Try to recognize polyatomic ions with metals. Most of you would have CORRECTLY put NiC 2 N 2 Try to recognize polyatomic ions with metals.

#15 One billion molecules of water are in your hand; how many moles of molecules are you holding? One billion molecules of water are in your hand; how many moles of molecules are you holding? 1 x 10 9 molecules H 2 O (1 mole H 2 O) = 1 x 10 9 molecules H 2 O (1 mole H 2 O) = (6.022 x ) (6.022 x ) x moles H 2 O, bet you thought it would be a big number, didnt you? x moles H 2 O, bet you thought it would be a big number, didnt you?