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Representative Particles Whatever type of particle that is being examined.

Representative Particles Whatever type of particle that is being examined. Atom – any single element that is part of the overall compound. Ion – an atom or group of atoms that has a net charge Molecule – a group of atoms that have been chemically combined. There is no net charge on a molecule.

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Representative Particles Whatever type of particle that is being examined.

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  1. Representative Particles • Whatever type of particle that is being examined. • Atom – any single element that is part of the overall compound. • Ion – an atom or group of atoms that has a net charge • Molecule – a group of atoms that have been chemically combined. There is no net charge on a molecule.

  2. Determine how many atoms, ions and molecules are in each example: Pb(NO3)2 molecule ions atoms 5 (NH4)2SO4 molecules ions atoms

  3. The size of an atom, ion or molecule is too small to deal with on an individual basis in the lab. Therefore, normally in chemistry we deal in moles of atoms, ions or molecules. A mole can have multiple definitions: 1 mole = 6.022 E 23 (Avogadro’s number) = atomic weight in grams = 22.4 liters (for gases only)

  4. Molar Mass – the mass, in grams, of 1 mole of any substance. It is found by taking the atomic weight from the periodic table, and rounding to one place past the decimal. The molar mass of each of the following: Be = 9.0 grams Cr = 52.0 grams Cl = 35.5 grams S = 32.1 grams O = 16.0 grams

  5. Calculate the molar mass of the following: BeCl2, BeSO4, Cr(ClO3)3, Cr2(SO4)3 and (NH4)3PO4 BeCl2 : BeSO4 : Cr2(SO4)3 : (NH4)3PO4 :

  6. The Flux Capacitor Particles Mass 6.022 E23 molar mass Moles 22.4 Volume 1 mole = 6.022 E23 (particles) = molar mass (grams) = 22.4 (liters)

  7. What is the mass of 1.75 mole of NaCl? 1.75 mol NaCl 58.5 g NaCl = 102 g NaCl 1 mol NaCl How many moles of AgNO3 is 57.3 grams? What is the volume of 0.258 moles of CH4?

  8. How many moles of FeSO4 is 2.57 grams of FeSO4? • How many molecules are in 2.57 grams of FeSO4? • How many moles of oxygen are in 2.57 grams of FeSO4? • How many ions are in 2.57 grams of FeSO4?

  9. 0.0169 mol FeSO4 • 2. 1.02 E22 molc FeSO4 • 3. 0.0677 mol O • 4. 2.04 E 23 ions

  10. How many atoms are in 17.3 grams of Fe2O3? 3.26 E 23 atoms What is the mass of 1.16 E 21 molecules of Fe2O3? 0.307 g Fe2O3

  11. What is the mass of 617 molecules of MgSO4? • What is the volume of 18.7 grams of O2? • How many Freon molecules are in 0.1573 liters of Freon? • How many oxygen atoms are in 16.3 g of CuClO3? • What is the volume of 76.3 grams of mercury vapor?

  12. What is the volume of 16.3 g of O2? • How many molecules are there in 63.75 liters of CO2? • What is the mass of 9.47 E 25 molecules of CH4? • a. How many moles of PCl3 are in 16.8 grams of PCl3? • b. How many atoms are in 16.8 g of PCl3? • 5. What is the mass of 27.9 liters of NH3?

  13. What is the volume of 4.35 E 18 molecules of SO2? • How many atoms are in 15.3 liters of propane gas, C3H8? • What is the mass of 3.92 liters of HCCl3? • How many oxygen atoms are in 16.3 grams of K2Cr2O7? • What is the mass of 8.15 E 24 molecules of CCl4? • How many grams of HClO4 can be made from 9.13 E 24 oxygen atoms?

  14. % Composition - % by mass of each element in a compound • What is the % of each element in K2CrO4? • Calculate the molar mass • 2 (39.1) + 52.0 + 4 (16.0) = 194.2 grams • 2. Take the mass of each element and divide by the molar mass of the compound, and then multiply by 100% • % K = 78.2/194.2 x 100% = 40.3 % • % Cr = 52.0/194.2 x 100 % = 26.8 % • % O= 64.0/194.2 x 100 % = 33.0 %

  15. The total % should be between 99.8 – 100.2 % • What is the % composition of C3H8? • % C = • % H = • What is the % composition of NaHSO4? • % Na = % S = • % H = % O =

  16. How many grams of sodium are in 4.76 grams of NaHSO4? 0.912 g Na How many grams of oxygen are in 4.76 grams of NaHSO4? 2.54 g O

  17. Empirical Formula – lowest ratio of elements in a compound Molecular Formula – Actual number of elements in a compound MM = molecular mass EM = empirical mass MM/EM = whole number. Multiply subscripts of the empirical formula by the whole number to get the molecular formula. To get the empirical formula from the molecular formula, reduce the subscripts.

  18. What is the molecular formula of a compound with a molecular mass of 60.0 grams, and an empirical formula of CH4N? EM = 12.0 + 4 (1.0) + 14.0 = 30.0 grams MM/EM = 60.0/30.0 = 2 2 x (CH4N) = C2H8N2

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