Assume 100g sample

2. Assume 100g sample 35.51g C x = 2.9567 mol = 4.99 = 5 4.77 g H x = 4.72277 mol = 7.98 = 8 1 mol C 0.59156 mol 0.59156 mol 0.59156 mol 0.59156 mol 0.59156 mol 12.01g 37.85 g O x = 2.3656 mol = 3.99 = 4 1 mol H 1.01g 8.29 g N x = 0.5917 mol = 1.00 = 1 1 mol O 16.00g 13.60 g Na x = 0.59156 mol = 1.00 = 1 1 mol N 14.01g Empirical formula C5H8O4NNa 1 mol Na Molar mass of empirical formula - 169.13 g/mol 22.99g Therefore the empirical formula = molecular formula = C5H8O4NNa

3. HW answers: pg 110 • 3.07 x 1024 atoms S • 9.97 x 10-15mol Co • 3.44 x 10-10 g Pb • 409 g/mol • 6.69 x 1021 molecules C2H6 • a. 46.65% N b. 35.00% N c. 71.13% N d. 82.27% N • Empirical=molecular = C6H10S2O • 5.96 g F • a. CH2O b. KCN 53. C8H10N4O2

4. Chemical reactions and Stoichiometry Sections 3.7-3.8

5. How many toy tractor trailers can you make from the following? 350 tires 1125 truck frames 87 seats 15 steering wheels What additional information would you need to answer this problem?

6. Describing Chemical Reactions • A chemical reaction is the process by which one or more substances are changed into one or more different substances (NH4)2Cr2O7(s) N2(g) + Cr2O3(s) + 4H2O(g) “The reactant ammonium dichromate yields the products nitrogen, chromium (III) oxide and water vapor” products reactants

7. (NH4)2Cr2O7(s) N2(g) + Cr2O3(s) + 4H2O(g) A CHEMICAL EQUATION represents, with symbols and formulas, the identifies and relative amounts of the reactants and products in a chemical equation The physical state of the substance is placed after the formula as a subscript in parentheses. (s) – solid (g) – gas (l) – liquid (aq) – aqueous (dissolved in water)

8. heat → Pt → Δ →

9. Heat Chemical Equations Sulfur burns in oxygen to produce sulfur dioxide gas. S(s) + O2(g) When solid potassium is added to water, hydrogen gas and aqueous potassium hydroxide are produced K(s) + H2O(l) SO2(g) H2(g) + KOH(aq)

10. Indications of a Chemical Reaction • Evolution of heat and light is strong evidence that a chemical reaction has taken place! But, the evolution of heat or light by itself is not necessarily a sign of a chemical change since many physical changes also release either heat or light. • Production of gas! (aka bubbles when two substances are mixed) • Formation of precipitate! A solid that is produced as a result of a chemical reaction in solution and that separates from the solution is known as a precipitate • Color Change!

11. Characteristics of Chemical Equations • The equation must represent all reactants and products. • The equation must contain the correct formulas for the reactants and products • The law of conservation of mass MUST be satisfied!! Law of conservation of mass – atoms are neither created nor destroyed in ordinary chemical reactions To equalized numbers of atoms, coefficients are added in front of the formulas where necessary

12. Formation of Water Water is formed from oxygen gas and hydrogen gas. Using the atoms, form both reactants. Using only the atoms of the reactants, form the product. No atom of reactant can be left over. No more atoms can be taken from the box. (Hint: You may need more than one of the reactants/products in order for all atoms to be used in the products)

13. Practice Satisfying the Law of Conservation of MassBalancing Chemical Reactions ___H2 + ___Cl2 ___HCl ___ H2O  ___ H2 + ___ O2 ___ Mg + ___ HCl  ___ MgCl2 + ___ H2 ___ CaO + ___ SO2  ___ CaSO3 ___ H2SO3 + ___ O2  ___ H2SO4

14. Practice Satisfying the Law of Conservation of MassBalancing Chemical Reactions ___ Na + ___ F2  ___ NaF ___ Na + ___ H2O  ___ NaOH + ___ H2 ___ KClO3  ___ KCl + ___ O2 ___ C3H8 + ___ O2  ___ CO2 + ___ H2O ___ FeS + ___ HCl  ___ H2S + ___ FeCl2

15. How many toy tractor trailers can you make from the following? 350 g of tires 1125 g of truck frames 87 g of seats 15 g of steering wheels What additional information would you need to answer this problem?

16. Reaction Stoichiometry • Composition stoichiometry – deals with the mass relationships of elements in compounds • Ie. Mg(OH)2 – contains 1 Mg, 2 O, and 2 H • Reaction stoichiometry – involves the mass relationships between reactants and products in a chemical reaction • Ie. 1C4H8 + 6O2 4CO2 + 4H2O WE CAN ONLY COMPARE RELATIONSHIPS BETWEEN REACTANTS AND PRODUCTS USING MOLES

17. Reaction-Stoichiometry Problems Problem Type 1 Given: Amt of Cmpd A in mol Unknown: Amt of Cmpd B in mol mol A  mol B Problem Type 2 Given: Amt of Cmpd A in mol Unknown: Amt of Cmpd B in grams mol A  mol B  grams of B Problem Type 3 Given: Mass of Cmpd A in grams Unknown: Amt of Cmpd B in mol Grams of A  mol A  mol B • Problem Type 4 • Given: Mass of Cmpd A in grams • Unknown: Mass of Cmpd B in grams • Grams of A  mol A  mol B  grams B

18. How should be solve these problems? • 2Al2O3 4Al + 3O2 Given: mol Al Unknown: mol O2 • 2HgO  2Hg + O2 Given: g HgO Unknown: mol Hg • 4NH3 + 6NO  5N2 + 6H2O Given: mol NO Unknown g H2O • 2Al + 3H2SO4  Al2(SO4)3 + 3H2 Given: g Al Unknown: g aluminum sulfate

19. Mole Ratio • Mole ratio – a conversion factor that relates the amounts in moles of any two substances involved in a chemical reaction • 2Al2O3 4Al + 3O2 2 mol Al2O3 or 4 mol Al . 4 mol Al 2 mol Al2O3 2 mol Al2O3 or 3 mol O2 . 3 mol O2 2 mol Al2O3 4 mol Al or 3 mol O2 3 mol O2 4 mol Al

20. What mole ratios can we make? • 2Al2O3 4Al + 3O2 • 2HgO  2Hg + O2 • 4NH3 + 6NO  5N2 + 6H2O • 2Al + 3H2SO4  Al2(SO4)3 + 3H2

21. 4NH3 + 6NO  5N2 + 6H2O You have 0.345g ammonia. • How many grams of nitrogen monoxide do you need? • How many cL of nitrogen gas are produced? • Water has a density of 1g/mL. How many cm3 of water is produced?

22. 4NH3 + 6NO  5N2 + 6H2O You have 0.345g ammonia. • How many grams of nitrogen monoxide do you need? • How many cL of nitrogen gas are produced? • Water has a density of 1g/mL. How many cm3 of water is produced?