1. Chapter 3 Stoichiometry http://www.shodor.org/UNChem/basic/stoic/

2. THINK Why do the masses on the periodic table have decimals if we can’t have part of a proton or a neutron? http://richardbowles.tripod.com/chemistry/structure/structure.htm

3. 1961: Scientists decided to have a standard of masses, they chose Carbon. They decided it has a mass of 12 atomic mass units (amu) and base all other elements on this. Example: He is 1/3 the mass of Carbon. What is Heliums atomic mass? http://richardbowles.tripod.com/chemistry/structure/structure.htm

4. Calculating the Mass of a Compound CompoundFormulaFormula Mass Table salt Potassium Bromide Aluminum Hydroxide Magnesium Iodide

5. Calculating the Mass of a Molecule MoleculeFormulaMolecularMass Water Dinitrogen Pentoxide Simple Sugar Sulfur Dioxide

6. THINK What is the difference between a compound and a molecule?

7. A.M.U?!?!?! Define: Units: Examples and Calculations: http://en.wikipedia.org/wiki/Atomic_mass_unit

8. What is Stoichiometry? Define: http://www.chem4kids.com/files/react_stoichio.html

10. What is a mole? Definition: (and citation) Value: Another name for this value: What does it mean? (in your own words!) http://www.youtube.com/watch?v=1R7NiIum2TI

11. Conversions 1 mole= atomic mass of substance 1 mole= 6.022 X 10 23 atoms 1 mole= 22.4L

12. 1 mole of Ag= 1 mole of H 2 O= 1 mole of CO 2 How many grams, liters and atoms are in the following?

13. Mole-Gram Conversions Use Dimensional Analysis to calculate the answer to the following: How many moles are in 11.5 grams of C 2 H 5 OH? http://dbhs.wvusd.k12.ca.us/webdocs/Mole/Moles-to-Grams.html

14. How many moles of water are in 1.20X10 25 atoms? If the volume of Nitrogen gas is 75.0 L, how many grams are present?

15. How many atoms are in 16.2 grams of N 2 ? How much volume of ammonia will be present in 45.2 grams?

16.  If there are 44.5L of Hydrogen gas, how many grams are present?

17. Percent composition from Formula The subscripts in a formula represent not only the atom ration in which the different elements are combined, but also the ______________ ____________. FormulaAtom Ratio Mole Ratio H2OH2O KNO3 C 12 H 22 O 11 http://www.chemcool.com/regents/molesstoichiometry/aim4.htm

18. Examples Sodium hydrogen carbonate, commonly called “bicarbonate of soda”, is used in many commercial products to relieve an upset stomach. It has the formula NaHCO3. What are the mass percents of Na, H, C, and O in sodium hydrogen carbonate?

19. How to Solve % of element = ____________________ x 100 ElementNumber of Moles Atomic MassMolar Mass Compound mass =

20. Use these numbers to determine the percent of each component:

21. Example 2 An iron containing mineral responsible for the red color of soil in many parts of the country is limonite, which has a formula Fe 2 O 3 3/2 H 2 O. What mass of iron in grams can be obtained from a metric ton (103 kg = 106 g) of limonite?

23. Simplest Formula from Chemical Analysis Simplest formula: Gives the simplest _____________________ ___________ of the atoms present. http://www.carlton.srsd119.ca/chemical/Molemass/empirical_formula.htm

24. Example A 25.0 g sample of an orange compound contains 6.64 g of potassium, 8.84 g of chromium, and 9.52 g of oxygen. Find the simplest formula.

25. How To Solve  Change all grams to moles for comparisons.  Calculate the mole ratio.  Make them all whole numbers.  Because the mole ratio is the same as the atom ratio, you are done!! Just write the final answer and box it!

26. Example 2 When a sample of ethyl alcohol is burned in air it is found that 5.00 grams of ethyl alcohol convert to 9.55 grams of carbon dioxide, and 5.87 grams of water. What is the simplest formula of ethyl alcohol? (Hint: Find the mass of each ELEMENT first!! Then continue the problem)

28. Molecular formula from Simplest Formula The molecular formula is a _______________________ ________________ of the simplest formula.

29. Example Vitamin C’s formula is found to be C3H4O3. From an experiment the molecular mass is found to be 180 g/mol. What is the molecular formula of vitamin C?

30. How To Solve It  Find the simplest formula  Figure out what to multiply by determining the ration of the simplest to the molecular masses.

31. Writing and Balancing Equations word: formula:

32. Balancing Equations Ca + O 2  CaO Mg + N 2  Mg 3 N 2 AgNO 3 + Cu  Cu(NO 3 ) 2 + Ag http://richardbowles.tripod.com/chemistry/balance.htm

33. Mass Relations from Equations The coefficients of a balanced equation represent the number of _______________ of reactant and products

34. Example Ammonia is used in fertilizer and is made by reacting nitrogen of the air with hydrogen. (a) How much ammonia (in grams) is formed from 1.34 mol of nitrogen? (b) how much nitrogen (in grams) is required to form 1.00 kg of ammonia? (c) How much hydrogen (in grams) is needed to react with 6.00 grams of nitrogen?

35. How To Solve It  Write a balanced equation for this reaction  Use the mole rations (coefficients of the reaction) to relate moles of one substance to moles of another.  Change from moles to grams.

36. Limiting Reactant Limiting reactant: The reactant that _________________ the amount of _____________. http://www.chem.tamu.edu/class/majors/tutorialnotefiles/limiting.htm

37. Example If 3.5 grams of copper is added to 6.0 grams of AgNO3, which one is the limiting reactant? Cu + AgNO 3  Cu(NO 3 ) 2 + Ag

38. How To Solve It Take grams of reactant #1 and find the mass of the product. Take grams of reactant #2 and find the mass of the product. The reactant that produces less product is the limiting reactant

39. Example 2 Identify the limiting reactant when 1.7 grams of sodium reacts with 2.6 L of chlorine to produce salt. Na + Cl 2  NaCl

41. Experimental Yield; Percent Yield Percent Yield: Actual Yield: Expected Yield: http://www.800mainstreet.com/6/0006-007-percent-yield.html

42. Example A piece of copper with a mass of 5.00 grams is placed in a solution of silver nitrate. The silver metal that is produced has a mass of 15.2 grams. What is the percent yield? [Hint: 5.00 g Cu -> ? g Ag (theoretical yield)] Cu + AgNO3  Cu(NO3)2 + Ag

43. Example 2 Determine the percent yield for the reaction between 2.80 grams of Al(NO3)3 and excess NaOH if 0.966 grams of Al(OH)3 is recovered. Al(NO3)3 + NaOH  NaNO3 + Al(OH)3