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Ch10.1 – The Mole 1 mol = 6.02 x 10 23 particles This is called Avogadro’s Number *Think of it as a chemist’s dozen (A dozen donuts or a mole of donuts?) Can be used for atoms, ions, molecules, donuts, oranges, grains of sand, chevys, etc. Why that number? -Since 1 amu = 1.66 x 10 -24 g: = 1 x602 000 000 000 000 000 000 000.000 000 000 000 000 000 000 00166

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The Mole Can use as a unit for counting numbers Atoms are too small to count individually and there are too many, so we need a way to bundle a bunch, like having a dozen oranges = 12 oranges 1 mole = 6.02 x 10 23 particles This is hard to understand, so let’s relate it. Did You Know??? 1.A grain of rice has an average mass of 1.75 x 10 -5 kg. What is the mass of one mole, 6.02 x 10 23, grains of rice? 1.05 x 10 19 kilograms This is hard to understand, so let’s change this mass to the mass of cars. This would require a million cars per person to equal this mass!! 2.You can count the number of oranges in 6 dozen in a few minutes. Six moles of oranges would have a mass as large as the entire Earth! 3.Avogadro’s number (1 mole) is so large, if you could count 100 particles every minute and counted 12 hrs every day, and had every person on Earth also counting, it would take more than 4 million years to count a mole of anything! 4.To obtain Avogadro’s number in grains of sand, it would be necessary to dig up the entire surface of the Sahara Desert, an area of 8 x 10 6 km 2 (an area slightly less than the area of the U.S.), to a depth of 200m.

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Conversions: or 6.02 x 10 23 particles 1 mol6.02 x 10 23 particles 1 mol Ex 1) How many moles of Mg are 3.01 x 10 22 atoms? Ex 2) How many molecules are 4.00 mol of glucose, C 6 H 12 O 6 ? HW #2) How many atoms are 0.360mol of Silver?

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Gram Formula Mass Ex3)He weighsor C weighsor The mole # was chosen so that the # on the Periodic Table can be read in grams. *Round masses to nearest 1 / 10 * Ex4)H1.0079 F18.998403 Cl35.453

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Ex5) Find the molecular mass of: H 2 O NaCl Mg 3 (PO 4 ) 2 Ch 10 HW #1 1 – 7

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1) How many moles in 2.80 x 10 24 atoms of silicon? 3) How many oxygen atoms in each: A) NH 4 NO 3 B) C 9 H 8 O 4 C) O 3 D) C 3 H 5 (NO 3 ) 3

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Ch10 HW#1 1 – 7 1) How many moles in 2.80 x 10 24 atoms of silicon? 2) (In class) 3) How many oxygen atoms in each: A) NH 4 NO 3 B) C 9 H 8 O 4 C) O 3 D) C 3 H 5 (NO 3 ) 3 2.80 x 10 24 atoms 6.02 x 10 25 atoms 1 moles = 4.65 moles

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Ch10 HW#1 1 – 7 1) How many moles in 2.80 x 10 24 atoms of silicon? 2) (In class) 3) How many oxygen atoms in each: A) NH 4 NO 3 3 B) C 9 H 8 O 4 4 C) O 3 3 D) C 3 H 5 (NO 3 ) 3 9 2.80 x 10 24 atoms 6.02 x 10 25 atoms 1 moles = 4.65 moles

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4) How many molecules in 2.14 mol CO? 5) How many moles in 4.65 x 10 24 molecules of NO 2 ?

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4) How many molecules in 2.14 mol CO? 5) How many moles in 4.65 x 10 24 molecules of NO 2 ? 2.14 mol CO 1 mol CO = 1.29 x 10 24 molecules 6.02 x 10 23 molecules

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4) How many molecules in 2.14 mol CO? 5) How many moles in 4.65 x 10 24 molecules of NO 2 ? 2.14 mol CO 1 mol CO = 1.29 x 10 24 molecules 4.63 x 10 24 molecules 6.02 x 10 23 molecules 1 moles = 7.72 moles 6.02 x 10 23 molecules

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6) Gram molecular mass A. C 2 H 6 B. PCl 3 C. C 3 H 7 OHD. N 2 O 5

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6) Gram molecular mass A. C 2 H 6 B. PCl 3 C. C 3 H 7 OHD. N 2 O 5 2 C @ 12.0 = 24.0 1 P @ 31.0 = 31.0 6 H @ 1.0 = 6.0 3 Cl @ 35.5 = 106.5 30.0 g / mol 137.5 g / mol

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6) Gram molecular mass A. C 2 H 6 B. PCl 3 C. C 3 H 7 OHD. N 2 O 5 2 C @ 12.0 = 24.0 3 C @ 12.0 = 36.0 1 P @ 31.0 = 31.0 2 N @ 14.0 = 28.0 6 H @ 1.0 = 6.0 8 H @ 1.0 = 8.0 3 Cl @ 35.5 = 106.5 5 O @ 16.0 = 80.0 30.0 g / mol 10 @ 16.0 = 16.0 137.5 g / mol 60.0 g / mol 108.0 g / mol

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7) Gram Formula Mass A. Sr(CN) 2 B. NaHCO 3 C. Al 2 (SO 3 ) 3

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7) Gram Formula Mass A. Sr(CN) 2 B. NaHCO 3 C. Al 2 (SO 3 ) 3 1 Sr @ 87.6 = 87.6 2 C @ 12.0 = 24.0 2 N @ 14.0 = 28.0 139.6 g / mol

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7) Gram Formula Mass A. Sr(CN) 2 B. NaHCO 3 C. Al 2 (SO 3 ) 3 1 Sr @ 87.6 = 87.6 2 C @ 12.0 = 24.0 2 N @ 14.0 = 28.0 139.6 g / mol 1 Na @ 23.0 = 23.0 1 H @ 1.0 = 1.0 1 C @ 12.0 = 12.0 3 O @ 16.0 = 48.8 83.8 g / mol

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7) Gram Formula Mass A. Sr(CN) 2 B. NaHCO 3 C. Al 2 (SO 3 ) 3 1 Sr @ 87.6 = 87.6 2 C @ 12.0 = 24.0 2 N @ 14.0 = 28.0 139.6 g / mol 1 Na @ 23.0 = 23.0 1 H @ 1.0 = 1.0 1 C @ 12.0 = 12.0 2 Al @ 27.0 = 54.0 3 S @ 32.1 = 96.3 9 O @ 16.0 = 144.0 294.3 g / mol 3 O @ 16.0 = 48.8 83.8 g / mol

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Ch10.2 – Mole/Mass Conversions Ex 1) How many grams are in 7.20 mol of dinitrogen trioxide? Ex 2) How many grams are in 3.41 mol of calcium oxide? Ex 3) Find the number of moles in 92.81g of Iron (III) Oxide?

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Ch10.2 – Mole/Mass Conversions Ex 1) How many grams are in 7.20 mol of dinitrogen trioxide? Ex 2) How many grams are in 3.41 mol of calcium oxide? 7.20 mol N 2 O 3 1 mol N 2 O 3 = 547 grams N 2 O 3 76.0 grams N 2 O 3 2 N @ 14.0 = 28.0 3 O @ 16.0 = 48.0 76.0 g / mol = 191 grams CaO Ex 3) Find the number of moles in 92.81g of Iron (III) Oxide? =.581 Moles

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HW#8) Find the mass of each: a)0.720 mol Be b) 2.40 mol N 2 (finish c, d) HW#9) Find # of moles in each: b) 0.000264g Li 2 HPO 4 (finish #9) Ch 10 HW#2 8, 9

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Ch3 X.C. Average Density of Earth. Given: Diameter E = 12,756 km Mass E = 5.98x10 24 kg Volume Θ = 4/3 πr 3 Diameter E 12756 km 2 2 Volume E = 4/3. πr 3 = 4/3. π(637,800,000 cm) 3 = 1.09x10 27 cm 3 Mass E = 5.98 x 10 24 kg 5.98 x 10 27 g m 5.98 x 10 27 g V 1.09 x 10 27 cm 3 Radius E = = = 6378 km = 637,800,000 cm D= = = 5.50 g/cm 3

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Ch10 HW#2 8 – 9 8c) Convert to mass: 10.0 mol Cr d) 3.32 mol K

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Ch10 HW#2 8 – 9 8c) Convert to mass: 10.0 mol Cr 52.0g Cr 1 mol Cr= 520g Cr d) 3.32 mol K 39.1 g K 1 mol K= 130 g K

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Ch10 HW#2 8 – 9 8c) Convert to mass: 10.0 mol Cr 52.0g Cr 1 mol Cr= 520g Cr d) 3.32 mol K 39.1 g K 1 mol K= 130 g K 9) Find moles a) 5.00g H 2 c) 72.0g Ar d) 3.70x10 -1 g

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Ch10 HW#2 8 – 9 8c) Convert to mass: 10.0 mol Cr 52.0g Cr 1 mol Cr= 520g Cr d) 3.32 mol K 39.1 g K 1 mol K= 130 g K 9) Find moles a) 5.00g H 2 1 mol H 2 2.0 g H 2 = 2.5 mol H 2 c) 72.0g Ar 1 mol Ar 39.9g Ar= 1.80 mol Ar d) 3.70x10 -1 g 1 mol B 10.8g B=

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Ch10.3 – Using the Mole Ex) What is the mass of 3.01x10 23 atoms of Carbon? Ex) What is the mass of 12.04x10 23 molecules of oxygen? Ex) How many molecules are there in 63.8g of ethanol, CH 3 OH? Ch10 HW #3 (10-12)

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Ch10.3 – Using the Mole Ex) What is the mass of 3.01x10 23 atoms of Carbon? 3.01x10 23 atoms C 1 mol C 12.0 g C 6.02x10 23 atoms C 1 mol C = 6.00g C Ex) What is the mass of 12.04x10 23 molecules of oxygen? 12.04x10 23 molecules O 2 1 mol O 2 32.0g O 2 6.02x10 23 molec. O 2 1 mol O 2 = 64.0g O 2 Ex) How many molecules are there in 63.8g of ethanol, CH 3 OH? 63.8g CH 3 OH 1 mol CH 3 OH6.02 x 10 23 molecules CH 3 OH 32.0g CH 3 OH 1 mol CH 3 OH = 1.20 x 10 24 molecules CH 3 OH Ch10 HW #3 (10-12)

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Lab10.1 – Molar Mass - due tomorrow - Ch10 HW#3 due at beginning of period

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Ch10 HW #3 10 – 12 10) What is the mass of 2.11 x 10 24 molecules of sulfur dioxide? 2.11 x 10 24 molecules SO 2 1 S @ 32.1 = 32.1 2 0 @ 16 = 32.0 64.1 g / mol

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10) What is the mass of 2.11 x 10 24 molecules of sulfur dioxide? 2.11 x 10 24 molecules SO 2 = 224g SO 2 1 moles SO 2 64.1g SO 2 6.02 x 10 23 molecules SO 2 1 moles SO 2 1 S @ 32.1 = 32.1 2 0 @ 16 = 32.0 64.1 g / mol

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11) What is the mass of 1.0 x 1022 molecules of iodine? 1.0 x 10 22 molecules I 2 2 I @ 126.9 = 253.8 g / mol

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11) What is the mass of 1.0 x 1022 molecules of iodine? 1.0 x 10 22 molecules I 2 = 4.22g I 2 1 moles I 2 253.8g I 2 6.02 x 10 23 molecules I 2 1 moles I 2 2 I @ 126.9 = 253.8 g / mol

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126.7g C 6 H 12 O 6 6 C @ 12.0 = 72.0 12 H @ 1.0 = 12.0 6 O @ 16.0 = 96.0 180.0 g / mol 12) How many molecules is 126.7g of sucrose?

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126.7g C 6 H 12 O 6 = 4.23 x 10 23 molecules C 6 H 12 O 6 1 mol C 6 H 12 O 6 6.02 x 10 23 molecules C 6 H 12 O 6 1 mol C 6 H 12 O 6 6 C @ 12.0 = 72.0 12 H @ 1.0 = 12.0 6 O @ 16.0 = 96.0 180.0 g / mol 180.0g C 6 H 12 O 6

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Ch10.4 – Volume of a Mole of Gas Volumes of gases can change a lot, if temp or pressure change. Standard temperature and pressure: (STP) Temp: 0°C (273K) Pressure: 101.3 kPa (kiloPascals) or 1 atmosphere At STP, 1 mole of any gas occupies a volume of 22.4 Liters. 22.4 L 1 mol 22.4 L or

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Ch10.4 – Volume of a Mole of Gas Volumes of gases can change a lot, if temp or pressure change. Standard temperature and pressure: (STP) Temp: 0°C (273K) Pressure: 101.3 kPa (kiloPascals) or 1 atmosphere At STP, 1 mole of any gas occupies a volume of 22.4 Liters. Ex 1) What is the volume of 0.600 mol of SO 2 gas at STP? 22.4 L 1 mol 22.4 L or

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Ch10.4 – Volume of a Mole of Gas Volumes of gases can change a lot, if temp or pressure change. Standard temperature and pressure: (STP) Temp: 0°C (273K) Pressure: 101.3 kPa (kiloPascals) or 1 atmosphere At STP, 1 mole of any gas occupies a volume of 22.4 Liters. Ex 1) What is the volume of 0.600 mol of SO 2 gas at STP? 22.4 L 1 mol 22.4 L or 0.600 mol SO2 = 13.4 L SO 2 22.4 L SO 2 1 mol SO 2

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Ex 2) Determine the # of moles in 33.6 L of He gas at STP: Ex 3) The density of a gaseous compound of C and O is 1.964 g / L at STP. Determine the gram formula mass. Is it CO or CO 2 ? CO: 1 C @ 12.0 = 12.0 1 O @ 16.0 = 16.0 20.0 g / mol CO 2 : 1 C @ 12.0 = 12.0 2 O @ 16.0 = 32.0 44.0 g / mol

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Ex 2) Determine the # of moles in 33.6 L of He gas at STP: Ex 3) The density of a gaseous compound of C and O is 1.964 g / L at STP. Determine the gram formula mass. Is it CO or CO 2 ? 1.964g 1 L = 1.50 mol He 1 mol He 22.4 L He CO: 1 C @ 12.0 = 12.0 1 O @ 16.0 = 16.0 20.0 g / mol CO 2 : 1 C @ 12.0 = 12.0 2 O @ 16.0 = 32.0 44.0 g / mol

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Ex 2) Determine the # of moles in 33.6 L of He gas at STP: Ex 3) The density of a gaseous compound of C and O is 1.964 g / L at STP. Determine the gram formula mass. Is it CO or CO 2 ? 1.964g 1 L = 1.50 mol He 1 mol He 22.4 L He 1.964g 1 L = 44.0 g / mol 1 mol 22.4 L CO: 1 C @ 12.0 = 12.0 1 O @ 16.0 = 16.0 20.0 g / mol CO 2 : 1 C @ 12.0 = 12.0 2 O @ 16.0 = 32.0 44.0 g / mol

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Ex4) 10.4g of dry ice, CO 2, is allowed to sublime into a gas. If the gas is brought to STP, what volume does it occupy? Ex5) 1.13x10 22 molecules of hydrogen gas occupy what volume at STP?

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Ex4) 10.4g of dry ice, CO 2, is allowed to sublime into a gas. If the gas is brought to STP, what volume does it occupy? = 5.29L CO 2 10.4g CO 2 1 mol CO 2 22.4L CO 2 44.0g CO 2 1 mol CO 2 Ex5) 1.13x10 22 molecules of hydrogen gas occupy what volume at STP?

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Ex4) 10.4g of dry ice, CO 2, is allowed to sublime into a gas. If the gas is brought to STP, what volume does it occupy? = 5.29L CO 2 10.4g CO 2 1 mol CO 2 22.4L CO 2 44.0g CO 2 1 mol CO 2 Ex5) 1.13x10 22 molecules of hydrogen gas occupy what volume at STP? =.420L H 2 1.13x10 22 molecules H 2 1 mol H 2 22.4L H 2 6.02x10 23 molecules H 2 1 mol H 2 Ch 10 HW #4 13-18

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Ch 10 HW#4 13-18 ( XC for correct #16 ) 13) 3 balloons each contain the same # of molecules of 3 different gases @ STP. Same mass? Same volume? CO 2 O2O2 H2H2

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Ch 10 HW#4 13-18( XC for correct #16 ) 13) 3 balloons each contain the same # of molecules of 3 different gases @ STP. Same mass? Same volume? CO 2 O2O2 H2H2 Diff mass Same volume

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14) Volume @ STP a) 3.20x10 -3 mol CO 2 b) 0.960 mol CH 4 c) 3.70 mol N 2 15) At STP, how many moles? a) 67.2L SO 2 b) 0.880L He c) 1.00x10 3 L C 2 H 6

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14) Volume @ STP a) 3.20x10 -3 mol CO 2 22.4L CO 2 1 mol CO 2 =.0717l CO 2 b) 0.960 mol CH 4 22.4L CH 4 1 mol CH 4 = 21.5L CH 4 c) 3.70 mol N 2 22.4L N 2 1 mol N 2 = 82.9L N 2 15) At STP, how many moles? a) 67.2L SO 2 1 mol SO 2 22.4 L SO 2 = b) 0.880L He 1 mol He 22.4 L He= c) 1.00x10 3 L C 2 H 6 1 mol C 2 H 6 22.4 L C 2 H 6 =

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14) Volume @ STP a) 3.20x10 -3 mol CO 2 22.4L CO 2 1 mol CO 2 =.0717l CO 2 b) 0.960 mol CH 4 22.4L CH 4 1 mol CH 4 = 21.5L CH 4 c) 3.70 mol N 2 22.4L N 2 1 mol N 2 = 82.9L N 2 15) At STP, how many moles? a) 67.2L SO 2 1 mol SO 2 22.4 L SO 2 = 3.00 mol SO 2 b) 0.880L He 1 mol He 22.4 L He=.0393 mol He c) 1.00x10 3 L C 2 H 6 1 mol C 2 H 6 22.4 L C 2 H 6 = 44.6 mol C 2 H 6

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16) AT STP what volume does 12.2g fluorine gas occupy? 12.2 g F 2 1 mol F 2 22.4 L F 2 38.0 g F 2 1 mol F 2 = 17) 13.0 x 10 24 molecules of Argon occupy what volume at STP? 13.0 x 10 24 molecules Ar 1 mol Ar 22.4 L Ar 6.02 x 10 23 1 mol Ar= molecules Ar

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16) AT STP what volume does 12.2g fluorine gas occupy? 12.2 g F 2 1 mol F 2 22.4 L F 2 38.0 g F 2 1 mol F 2 = 7.19 L F 2 17) 13.0 x 10 24 molecules of Argon occupy what volume at STP? 13.0 x 10 24 molecules Ar 1 mol Ar 22.4 L Ar 6.02 x 10 23 1 mol Ar= molecules Ar

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16) AT STP what volume does 12.2g fluorine gas occupy? 12.2 g F 2 1 mol F 2 22.4 L F 2 38.0 g F 2 1 mol F 2 = 7.19 L F 2 17) 13.0 x 10 24 molecules of Argon occupy what volume at STP? 13.0 x 10 24 molecules Ar 1 mol Ar 22.4 L Ar 6.02 x 10 23 1 mol Ar= 484 L Ar molecules Ar

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18) The densities of 3 gases: A: 1.25 g/L B: 2.86 g/L C:0.714 g/L Calculate the gFm of each (g/mol) ID as NH 3, SO 2, Cl 2, N 2, or CH 4 A)1.25 g 22.4 L 1 L 1 mol= B) 2.86 g 22.4 L 1 L 1 mol= C) 0.714 g 22.4 L 1 L 1 mol= NH 3 : 1N @ 14.0 = 14.0 3N @ 1.0 = 3.0 17.0 g/mol SO 2 : 1 S @ 32.1 = 32.1 2 O @ 16.0 = 32.0 64.1 g/mol Cl 2 : 2 Cl @ 35.5 = 71.0 g/mol N 2 : 2 N @ 14.0 = 28.0 g/mol CH 4 : 1 C @ 12.0 = 12.0 4 N @ 1.0 = 4.0 16.0 g/mol

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18) The densities of 3 gases: A: 1.25 g/L B: 2.86 g/L C:0.714 g/L Calculate the gFm of each (g/mol) ID as NH 3, SO 2, Cl 2, N 2, or CH 4 A)1.25 g 22.4 L 1 L 1 mol= 28.0 g/mol B) 2.86 g 22.4 L 1 L 1 mol= 64.1 g/mol C) 0.714 g 22.4 L 1 L 1 mol= 16.0 g/mol NH 3 : 1N @ 14.0 = 14.0 3N @ 1.0 = 3.0 17.0 g/mol SO 2 : 1 S @ 32.1 = 32.1 2 O @ 16.0 = 32.0 64.1 g/mol Cl 2 : 2 Cl @ 35.5 = 71.0 g/mol N 2 : 2 N @ 14.0 = 28.0 g/mol CH 4 : 1 C @ 12.0 = 12.0 4 N @ 1.0 = 4.0 16.0 g/mol

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Ch10.5 – More Conversions Ex1) One copper cylinder from the last lab had a mass of 57.68g. How many copper atoms is that? Ex2) Dinitrogen monoxide is stored in a 2.00 L cylinder at STP. What mass is this?

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Ch10.5 – More Conversions Ex1) One copper cylinder from the last lab had a mass of 57.68g. How many copper atoms is that? 57.68g Cu 1 moles Cu 6.02x10 23 atoms 63.5g Cu 1 moles Cu= 5.47x10 23 atoms Cu Ex2) Dinitrogen monoxide is stored in a 2.00 L cylinder at STP. What mass is this? 2.00 L N 2 O 1 moles N 2 O 44.0 g N 2 O 22.4 L N 2 O 1 moles N 2 O = 3.93 g N 2 O

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Ex3) Hydrogen sulfide is a dangerous gas released in volcanoes. If a scientist collects 10.0 mL sample at STP, how many gas particles are present?

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Ex3) Hydrogen sulfide is a dangerous gas released in volcanoes. If a scientist collects 10.0 mL sample at STP, how many gas particles are present?.0100L H 2 S 1 mole H 2 S 6.02x10 23 particles H 2 S 22.4 L H 2 S 1 moles H 2 S = 2.69x10 20 particles Ch10 HW#4 Mid Ch Rev Problems

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Lab9.1 – Formulas and Oxidation Numbers Review - due 2 days - Mid Ch Rev due at beginning of period

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Ch10 Mid Chapter Review 1.How many atoms are in 1.23 moles of calcium? 2.How many grams are in 1.23 moles of calcium? 3.How many moles of carbon are in 5.5 g sample of carbon?

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4. How many moles of aluminum are there in 2.3x10 24 atoms? 5. How many liters are in 2.50 moles of hydrogen molecules, H 2 ?

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6. How many moles are in 3.04 liters of chlorine gas? 7. How many particles are in 55.6 g of calcium oxide? 8. How many liters of gas are produced when 10.3 g of dry ice, solid carbon dioxide, sublimes?

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1)How many moles in 1.50x10 23 molecules NH 3 ? 2) Calculate the gram formula mass of H 3 PO 4. 3 H@ 1 P @ 4 O @ 3) How many moles in 15.5 g SiO 2 ? Ch10 Review

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1)How many moles in 1.50x10 23 molecules NH 3 ? 1.50x10 23 molecules NH 3 1 mol NH 3 6.02x10 23 molecules NH 3 =.249 moles NH 3 2) Calculate the gram formula mass of H 3 PO 4. 3 H@ 1.0 = 3.0 1 P @ 31.0 = 31.0 = 98.0 g/mol 4 O @ 16.0 = 64.0 3) How many moles in 15.5 g SiO 2 ? Ch10 Review

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3) How many moles in 15.5 g SiO 2 ? 4) Find the mass of 1.50 moles C 5 H 12

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3) How many moles in 15.5 g SiO 2 ? 15.5 g SiO 2 1 mol SiO 2 60.1 g SiO 2 =.257 mol SiO 2 4) Find the mass of 1.50 moles C 5 H 12 1.50 moles C 5 H 12 72.0 g C 5 H 12 1 mol C 5 H 12 = 108 g C 5 H 12

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5) Calculate the volume of 7.6 mole Ar at STP. 6) Find the volume of 835 g SO 3 at STP.

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5) Calculate the volume of 7.6 mole Ar at STP. 7.6 mol Ar 22.4 L Ar 1 mol Ar= 170 L Ar 6) Find the volume of 835 g SO 3 at STP. 835g SO 3 1 mol SO 3 22.4 L SO 3 80.1 g SO 3 1 mol SO 3 = 234 L SO 3

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Chapter 10 Hw #4 19 – 22 19) Mass in grams of an atom of Hg? 1 atom Hg 1 mol Hg 200.6g Hg 6.02x10 23 atoms Hg 1 mol Hg= 3.33x10 -22 g 20) How many molecules are in a 4.00 L balloon (at STP) filled with carbon dioxide? Would the answer change if CO? 9.00L CO 2 1mol CO 2 6.02x10 23 molecules 22.4 L CO 2 1 mol CO 2 = 2.42x10 23 molecules 21) % comp a)9.03g Mg with 3.48g N 9.03g Mg3.48g N 12.51g totalx100%= 72%12.51g total x100%= 28% B) 29.0g Ag with 4.30g S 29.0g Ag 4.30g S 33.30g totalx100%= 87% 33.30g totalx100%= 13%

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22) % comp of ethane C 2 H 6 (assume 1 mol) 2 C @ 12.0 = 24.0 6 C @ 1.0 = 6.0 30.0 g/mol C: 24.0g CH: 6.0g H 30.0g total x100% = 80%30.0g total x100% = 20%

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Molarity Molarity – a measure of concentration, represented with the symbol (M) - defined as Molarity (M) = Moles of Solute/Liter of solution - solute the substance added to the solution Ex: NaCl added to pure water to make a salt water solution. solute solvent - sometimes the solution is measured in dm 3 instead 1L = 1 dm 3 Ex) What is the molarity of a solution made by dissolving 45.2g of Ca(OH) 2 in 250 mL of solution? 45.2 Ca(OH) 2 1 mol Ca(OH) 2 74.0g Ca(OH) 2 =.611 mL Ca(OH) 2 1 Ca @ 40.1 = 40.1 2 O @ 16.0 = 32.0KHDUdcm.611mL 2 H @ 1.0 = 2.0250mL =.250 L.250 L=2.44 M Ca(OH) 2 74.0 g/mol

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Ex) What is the molarity of a solution made by dissolving 10g of potassium chloride in 0.505 dm 3 of solution? 10g KCl 1 mol KCl 74.6g KCl=.134 mol KCl=.265 M KCl.505 L 1 K @ 39.1 = 39.1 1 Cl @ 35.5 = 35.5 74.6

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