Presentation on theme: "What does the little number below each"— Presentation transcript:
1What does the little number below each Element mean?What are its’ units?amu/atom
2one amu is defined as 1/12th What is an amuone amu is defined as 1/12thof12C
3Average atomic mass or atomic weight is determined by a mass spectroscope. example: Analysis of a sample of carbon was found to have the following isotopes12C – %13C – %14C – %What is the atomic weight of Carbon
5How high could you stack a mole of sheets of paper? How much is a mole?How high could you stack a mole of sheets of paper?
6How much would a mole of iron weigh? Could you lift it? Look on the back inside cover for amu and molex 1023 atoms of Fe55.85 amux g*=55.85 g1atom of Fe1 amu
7What is the Mole?One mole is equal to the number of carbon atoms in exactly grams of C-12: 6.02 x 1023 atoms
8The Shopping Mole x g/ mole 22.4 L / mole # of atoms or molecules6.02 x atoms or molecules/moleMolex g/ mole22.4 L / moleMass of atomor moleculevolume of gasThe Shopping Mole
9Calculate the numbers of atoms of cesium found in 3.57 moles of cesium Calculate the numbers of atoms of cesium found in 3.57grams of cesiumCalculate the mass of 4.82 x 1023 atoms of cesium
101. Calculate the mass of 4.65 moles of (NH4)2S Calculating the molar mass of a compound (NH4)2S1. Calculate the mass of 4.65 moles of (NH4)2S2. Calculate the numbers of atoms of nitrogen found in 3.57grams (NH4)2S3. Calculate the mass of nitrogen in 3.76 x 1024 formula units of (NH4)2S
11Determining Percent Composition of Compounds Given the compound: Al(HPO3)3What are the percent compositions of each of the atoms from which the above compound is constructed?Mass of Aluminum= 1 mol Al26.9 grams= 26.9g Almole of AlMass of hydrogen = 3 mols H1.01 gram= Hmole of H266 gAl(HPO3)3Mass of Phosphorus = 3 mols P30.9 gram= g Pmole of PMass of oxygen = 9 mols O16.0 gram= 144 g Omole of P
1210.1% Mass percent of Al: 1.13% Mass percent of H: 34.8% mass of Al26.9 g10.1%=x 100=Mass percent of Al:mass of Al(HPO3)3266 gmass of H3.03 gx 1001.13%=Mass percent of H:=mass of Al(HPO3)3266 gmass of P92.7 g34.8%x 100Mass percent of P:==mass of Al(HPO3)3266 gmass of O54.1%144 g==x 100Mass percent of O:266 gmass of Al(HPO3)3
13Empirical formulaA compound is composed of Cl 71.65% and C 24.27% and H 4.07% what is the empirical formula? The Molar mass is 98.96g/mole, what is the molecular formula?
140.255 g isopropyl alcohol is combusted Determining the Empirical Formula of a Compound Using Combustion AnalysisCombustion Analysis0.255 g isopropyl alcohol is combustedmass difference of H2O absorber = gmass difference of CO2 absorber = g
15mass difference of H2O absorber = 0.306 g mass difference of CO2 absorber = g1 mole CO212 g Cgrams of C: g CO2= 0.153g C44 g CO21 mole CO21 mole H2O2.02 g Hgrams of H: g H2O= g H18 g H2O1 mole H2Ograms of O: g g g H = g
16Assume that the empirical formula for the compound is C3H8O 1 mol C1C: g C= 2.97= mol C12 g C0.00431 mol H1H: g H= 7.91= mol C0.00431.01 g H11 mol OO: g O= 1.00= mol O0.004316 g OAssume that the empirical formula for the compound is C3H8O
17Ascorbic acid (Vitamin C) contains 40. 92 percent C, 4 Ascorbic acid (Vitamin C) contains percent C, 4.58 percent H, and percent O by mass. What is the empirical formula of ascorbic acid?Ethylene glycol, the substance used in automobile antifreeze, is composed of 48.7 % C, 9.7 percent H, and 51.6 percent O by mass. Its molar mass is62.1 g/mol. (a) What is the empirical formula of ethylene glycol? (b) What is the molecular formula
18So What is Stoichiometry? mass of A in g mole 3(moles C) C g = mass CA g 1(moles A) mole1A + 2B → 3C + 4D
19Na2SO3(aq) + 2AgNO3(aq) Ag2SO3(s) + 2NaNO3(aq) If 3.4 g of silver nitrate is mixed w/ excess sodium sulfite, what would be the theoretical yield for silver sulfite?in molesin formula unitsin L at STPin grams
20Na2SO3(aq) + 2AgNO3(aq) Ag2SO3(s) + 2NaNO3(aq) If 3.4 g of silver nitrate is mixed sodium sulfite, how many grams of sodium sulfite would you need to react completely?
21Na2SO3(aq) + 2AgNO3(aq) Ag2SO3(s) + 2NaNO3(aq) If 4.5 g of sodium sulfite is mixed w/ excess silver nitrate, what would be the theoretical yield for silver sulfite?What would be the percent yield if 4.1g was produced in the lab?
22Na2SO3(aq) + 2AgNO3(aq) Ag2SO3(s) + 2NaNO3(aq) If 4.3 g of silver nitrate is mixed w/ 3.2g sodium sulfite, what would be the theoretical yield for silver sulfite?How much of the excess reagent is left over?
23Using Stoichiometry in the Laboratory Na2SO3(aq) + 2AgNO3(aq) Ag2SO3(s) + 2NaNO3(aq)20 ml0.12 M20 ml0.35 M1. How many grams of silver sulfite would be produced?2. What would be the molarity of the sodium nitrate?