What the mole?!? You don’t scare me, Chapter 11!

For each question asked: ► Copy question (These are on the blog if you aren’t fast enough in class.) ► Determine which type of problem is being asked ► Set up problem (Solving is for homework.)

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

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

#3 ► What is the molar mass of chlorine gas?  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?

#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. ► Is that the correct formula for the compound?

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

#7 ► What percent of gypsum is actually water?

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

#9 ► 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?

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

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

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

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

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

Fine’ ► So, how did you do? ► your results to me for bonus points! (Shhhh, it’s our secret!!)  Valid only til 2/10/11……

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

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

#3 ► What is the molar mass of chlorine gas?  Be careful of the formula!! Chlorine is 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? ► 0.450mol Al 2 S 3 ( g Al 2 S 3 ) ► (1 mol Al 2 S 3 ) ► 67.6 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. ► 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 ► No, C 6 H 6 O 2 is the correct molecular formula.

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

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

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

#9 ► What is the average mass of 50 atoms of sulfur? ► 50 atoms S ( g S) = ► (6.022 x atoms S) ► x g S (Note: 4 sig figs) ► (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? ► CH

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

#12 ► How many molecules of CO 2 are in 44.10g of carbon dioxide? ► x molecules CO 2 ► The mass given happens to be the molar mass which IS the mass of Avogadro’s number for CO 2 This one of those that if you recognize that number as its molar mass, you don’t even have to calculate.

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

#14 ► What is the empirical formula of a compound containing:  10.52g nickel  4.38g carbon  5.10g nitrogen ► Ni(CN) 2 nickel (II) cyanide ► 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? ► 1 x 10 9 molecules H 2 O (1 mole H 2 O) = ► (6.022 x ) ► x moles H 2 O, bet you thought it would be a big number, didn’t you?