Tentative Chapter Three Assignments and Schedule Any and/or all problems will be collected each day and scored for correctness.

Transcription

1 Tentative Chapter Three Assignments and Schedule Any and/or all problems will be collected each day and scored for correctness. Date Video Due Book Section Problems Comments Readings One ,14,16,18,20 Balancing Equations, Simple Types of Rxns. Two 3.2 cont. names, formulas and balanced equations WS Electrolysis demo. Rxn demos. Read the caption for Figure 3.2, The difference between a subscript and a coefficient Three , 24 and in-class quiz quiz on writing balanced reactions Four ,30, 34,36,38 Mole Inter-conversions Five 3 LAB: Determining the ratio of reactants Six , 40, 46, 49 Empirical, Molecular Formulae, what is a hydrate? Seven 4 LAB: Determination of a Chemical Formula Eight 50, 51, 52 Combustion Analysis, continue lab Nine ,4,5,6, 56,57,58 Stoichiometry Ten 6 60,62,63,66 Finish lab Eleven ,71,72,74 ( d is optional), 76 Limiting Reactants Twelve Review Ch3 93, 99 and take home quiz problems assigned Thirteen Ch3 Test Take home quiz problems due

2 Names, Formulas and Balanced Equations Worksheet Name: W 2 O 5 Ni(CH 3 COO) 2 C 2 H 6 HBr H 2 Se N 2 F 5 KMnO 4 C 4 H 10 Mo(SO 4 ) 2 HClO Ru(ClO 2 ) 4 P 4 O 8 SO 2 CO 2 PbS 2 SnC 2 O 4 V(IO 3 ) 5 Cd(BrO) 2 Write the formula: Cobalt III peroxide Mercury I sulfite Dinitrogen hexafluoride Propane Perbromic acid Silver nitrate Hyposulfurous acid Nitrogen trioxide Zinc phosphate Barium nitride Hexane Arsenic acid Fluorous acid Octane Lithium dichromate Iron II hydrogen carbonate Uranium VI fluoride Sulfurous acid Write the complete balanced chemical equation. 1) Gold combines with sulfur under the correct conditions to produce gold I sulfide. 2) Butane burns in oxygen to produce carbon dioxide and another wet product. 3) Calcium sulfate combines with nickel II phosphide to produce calcium phosphide and nickel II sulfate. 4) Aluminum perchlorate reacts with titanium IV sulfate to produce aluminum sulfate and titanium IV perchlorate. 5) Elemental strontium replaces hydrogen in water producing an explosive gas and the base strontium hydroxide.

3 3.1 Chemical Equations 2H 2(g) + O 2(g) 2H 2 O (l) (s) (l) (g) (aq) How many atoms of Mg, O and H are represented by 3Mg(OH) 2? Law of Conservation of Matter: Na (s) + H 2 O (l) NaOH (aq) + H 2(g) Another example: Fe + O 2 Fe 2 O Some Simple Patters of Chemical Reactivity Combination (sometimes called synthesis) Decomposition Combustion in air

4 3.3 Formula Weights Formula Weight Molecular Weight a.k.a. Formula Mass, Molecular Mass H 2 SO 4 C 6 H 12 O 6 Percentage Composition Calculate the percentage of carbon, hydrogen and oxygen (by mass) in C 12 H 22 O Avogadro s Number and the Mole Calculate the number of H atoms in mol of C 6 H 12 O 6 How many oxygen atoms are in 0.25 mol of Ca(NO 3 ) 2.

5 Molar Mass or Molar Weight 12 C Magnesium Au Notice that when we are dealing with a particular isotope of an element, we use the mass of that isotope; otherwise we use the atomic weight (the average atomic mass) of the element. The mass in grams of one mole of a substance is called the molar mass. What is the mass in grams of 1.00 mol of C 6 H 12 O 6 (a.k.a. glucose)? Calculate the number of moles of C 6 H 12 O 6 in 45.0g of glucose (C 6 H 12 O 6 ). Calculate the number of C 6 H 12 O 6 molecules in the 45.0g sample of glucose (C 6 H 12 O 6 ).. Interconverting between mass moles particles: Determine the number of a) moles of glucose (C 6 H 12 O 6 ) and b) oxygen atoms in 360.0g of glucose.

6 Determine the number of a) moles of CO 2(g) and b) grams of carbon dioxide gas in x molecules of CO 2(g). 3.5 Empirical Formulas from Analyses Ascorbic acid (vitamin C) contains 40.92% C, 4.85% H and 54.50% O by mass. What is the empirical formula of ascorbic acid?

7 Mesitylene, a hydrocarbon that occurs in small amounts in crude oil, has an empirical formula of C 3 H 4. the experimentally determined molecular weight of this substance is 121 amu. What is the molecular formula of mesitylene? Combo problem: Ethylene glycol, the substance used in automobile antifreeze, is composed of 38.7% C, 9.7% H and 51.6%O by mass. Its molar mass is 62.1 g/mol. a) What is the empirical formula of ethylene glycol? b) What is its molecular formula?

8 Combustion Analysis Isopropyl alcohol, a substance sold as rubbing alcohol, is composed of C, H and O. combustion of 0.255g of isopropyl alcohol produces 0.561g of CO 2 and 0.306g of H 2 O. Determine the empirical formula of isopropyl alcohol.

9 Another combustion analysis problem: Caproic acid, which is responsible for the foul odor of dirty socks, is composed of C, H and O atoms. Combustion of a 0.225g sample of this compound produces 0.512g CO 2 and 0.209g H 2 O. a) What is the empirical formula of caproic acid? b) Caproic acid has a molar mass of 116g/mol. What is its molecular formula?

10 3.6 Quantitative Information from Balanced Equations 3H 2 + N 2 2NH 3 Coefficients in a chemical equation represent the relative numbers of molecules (and therefore moles) involved in a reaction.which can be converted to mass. How many grams of water are produced in the oxidation of 80.0g of glucose (C 6 H 12 O 6 )? The balanced chemical equation is below. C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O Solid lithium hydroxide is used in space vehicles to remove exhaled carbon dioxide. The lithium hydroxide reacts with gaseous carbon dioxide to form solid lithium carbonate and liquid water. How many grams of carbon dioxide can be absorbed by 1.00g of lithium hydroxide?

11 3.7 Limiting Reactants Manufacture of cars. The limiting reactant or limiting reagent: How many moles of NH 3 can be formed from 3.0mol N 2 and 6.0mol of H 2? (note, example of using an i.c.e. table). The balanced chemical equation: 3H 2 + N 2 2NH 3

12 Consider the reaction: 2Al + 3Cl 2 2AlCl 3 A mixture of 54.0g of Al and 142.0g of Cl 2 are allowed to react in an enclosed vessel. a) which is the limiting reactant? b) how many moles of AlCl 3 are formed? c) how many moles of excess reactant remain at the end of the reaction?

13 A second limiter example: A 55.8g sample of pure iron is submerged in a solution containing 338.0g of silver nitrate. Fe(NO 3 ) 3 and solid silver are the products. a) write the balanced chemical reaction. b) determine the limiting reactant c) determine the moles of each product produced d) determine the mass of excess reactant remaining.

14 Theoretical Yields The quantity of product that is calculated to form when all of the limiting reactant reacts is called the theoretical yield. The amount of product actually obtained in a reaction is called the actual yield. Percent yield = In the last problem, two moles of silver were theoretically produced. a) calculate the mass of silver that would theoretically be produced. b) If 107.8g of silver are actually produced, calculate the percentage yield. In a second, new, chemical reaction, the actual yield of silver was 75.0%. How many grams of silver were actually produced?

15 Here is the list of "for sure" do problems: mixed (visualizing concepts): 2,4,5,6, balance equations/types rxns: 12,14,16,18,20, formula mass and % comp: 22(only some),24 (usually takes longer to do), mole (I like some of the ones that make them find the moles of particular elements in a molecule: e.g., 38d), but many of these problems have several parts...so they take awhile: 28,30,34,36,38,40, empirical/molecular formulas: 44,46(only one or two of them),48,50, general stoich probs: 56,58,60,62,66, limiter probs: 68,71,72,74 (probably not "d"),76 Here is a list of maybe do's and extras: 11,13,15,22(more if needed),46 (the rest of the problem if needed), Here is a list of quiz problems (partner, in-class, take-home or just "put them on the ch3 quiz" problems): 87,93 (if need more stoich),99 (if need more limiter), 107 (I usually give this one as a partner quiz...death by cyanide problem (kids like the name, but then they find it hard), but good review of dim analysis with stoich and some percentage stuff)