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Conversion Factors

Conversion Factors. Molar mass atomic mass in g = 1 mole Volume of gas at STP 1 mole gas = 22.4L Mole-mole ratio coefficients from balanced equation Avogadro’s number 6.02 x 10 23 molecules = 1 mole. Stoichiometry.

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Conversion Factors

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  1. Conversion Factors • Molar mass atomic mass in g = 1 mole • Volume of gas at STP 1 mole gas = 22.4L • Mole-mole ratio coefficients from balanced equation • Avogadro’s number 6.02 x 1023 molecules = 1 mole

  2. Stoichiometry g g mole X g mole Y L Molecules (gas at STP) Molar mass Molar mass 6.02 x 1023 molecules = 1 mole 22.4L=1 mol For great ion review game www2.stetson.edu/mahjongchem/

  3. 2AgNO3 + H2S Ag2S + 2HNO3 How many moles of Ag2S will be produced from 3.5 moles of AgNO3 3.5 mole AgNO3 x 1 mole Ag2S= 1.75 mole Ag2S 2 mole AgNO3 How many grams of HNO3 will form when 2.5g of H2S react? 2.5g H2S x 1 mol H2S x 2 mol HNO3 x 63.0g HNO3 34.1g H2S 1 mol H2S 1 mol HNO3 = 9.2g HNO3

  4. Molarity moles of solute L of solution Dilutions V1M1 = V2M2

  5. How can we make 500 ml of 1.00 M HCl from 6.00 M HCl? V1= ? M1= 6.00 M V2= .500L M2= 1.00 MV1(6.00M) = (.500L)(1.00M)V1 = .500L∙M= .0833L or 83.3ml 6.00M

  6. What is the molarity of 250ml solution containing 9.46g CsBr? ggmole 9.46g x 1 mole CsBr= 0.0444 mole CsBr 213 g CsBr 250 ml = .250 L M = 0.0444 mole= 0.178 M CsBr .250L

  7. The amount of heat gained or lost depends on the amount of reactants used. 2Na2O2 + 2H2O g 4NaOH + O2 + 215.76 kJ How much heat is released by the reaction of 5.0 moles of Na2O2? 5.0 moles Na2O2 x 215.76 kJ= 539.4 kJ 2 mole Na2O2 Heat of reaction (Qr) is negative for exothermic reactions, but positive for endothermic reactions. So Qr = -539.4 kJ

  8. The decomposition of potassium chlorate is an endothermic reaction. 2KClO3(s) + 89.5kJ g 2KCl(s) + 3O2(g) How much heat is absorbed to decompose 1.50 grams of solid KClO3? 1.50g KClO3 x 1 mole KClO3 x 89.5kJ 122.5 g KClO3 2 mole KClO3 = .548kJ

  9. Limiting Reactant 1 frame and 3 wheels are needed to create one tricycle If I have 10 frames and 12 wheels, how many tricycles can I make?

  10. N2H4 + 2H2O2gN2 + 4H2O Which is the limiting reactant when 0.750 moles of N2H4 is mixed with 0.500 mole of H2O2? If all the N2H4 is used, how much H2O2 would be needed? 0.750 mole N2H4 x 2mole H2O2 = 1.5 mole H2O2 1 mole N2H4 Do we have that much? No! So H2O2 is limiting

  11. N2H4 + 2H2O2gN2 + 4H2O How much of the excess reactant (in moles) remains unchanged? 0.500 moles H2O2 x 1 mole N2H4 = .250 mole 2 mole H2O2 0.750 mole - .250 mole = .500 mole N2H4 How much H2O would be formed? 0.500 mole H2O2 x 4 mole H2O = 1.00 mole H2O 2 mole H2O2

  12. % yield = actualx 100% theoretical If 5.50g of hydrogen reacts with nitrogen to form 20.4g of ammonia, what is the percent yield? N2(g) + 3H2(g) g 2NH3(g) Actual = 20.4g Theoretical = 5.50g H2 x 1 mol H2 x 2mol NH3 x 17.0g NH3 2.0g H2 3mol H2 1mol NH3

  13. % yield = actualx 100% theoretical • % yield = 20.4g x 100% = 65.4% 31.2g

  14. What is the molecular formula of the molecule that has an empirical formula of CH2O and a molar mass of 120.12 g/mol? Empirical formula mass: 12.0 + 2.0 + 16.0 = 30.0 amu X = 120.12 amu = 4 30.0 amu So C4H8O4 is the molecular formula.

  15. Determining empirical formula • Find the empirical formula of a compound that contains 53.7% iron and 46.3% sulfur. • % composition g mass of 100 g sample g moles g mole ratio • 53.7g x 1 mol/55.8g = .962 mol Fe 46.3g x 1 mol/32.1g = 1.44 mol S .962/.962 = 1, 1.44/.962 = 1.5 1:1.5 ratio x 2 = 2:3 ratio Fe2S3

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