Chapter 3 & 4: Stoichiometry part 2

Size: px

Start display at page:

Download "Chapter 3 & 4: Stoichiometry part 2"

Dora Walsh
6 years ago
Views:

1 Chapter 3 & 4: Stoichiometry part 2 Read: BLB 4.6 & 10.5 HW: BLB 4:81a,b, 83, 87; 10:26, 55, 57 18:26, 61 Supplemental: Rxns Know: Solution Stoichiometry and Titrations (Ch. 4) Gas phase Reactions (Ch. 10) Bonus deadline for SCT #8: FINAL SCT DEADLINE: Missed Exam 1, 2 or 3 due to an excused absence? Make-up Exam: Covers material from Exams 1 3, multiple choice. You must sign up by completing the request form & giving it to me (download). Need help?? Get help!! TAs in CRC (211 Whitmore) Final Exam: Dr. Lori S. Van Der Sluys Chem ! Determination of the concentration of a particular solute in a solution.! Can use: " Acid-Base reactions (neutralization) " Precipitation reactions " Redox reactions! Combine a reagent solution of KNOWN concentration with a sample of unknown concentration. Dr. Lori S. Van Der Sluys Chem

2 How do you calculate the unknown concentration?! At the end point or equivalence point of the titration, the reaction is stoichiometrically complete.! In acid-base titrations, the end point is reached when an indicator changes color. " dyes that change structure (and therefore color) " depends on acidic or basic solution " Phenolphthalein is clear in acid, and pink in base! At the end point, you know the exact moles of each reagent in solution from the balanced equation. " Moles of acid = Moles of base (monoprotic acid only!!) " M A V A = M B V B (monoprotic acid only!!) Dr. Lori S. Van Der Sluys Chem Example Titration:! 35.0 ml of M NaOH is required to titrate 10.0 ml of an HCl solution. What is the HCl concentration? Dr. Lori S. Van Der Sluys Chem

3 Example Titration:! ml of M HBr solution is titrated with M NaOH solution. How many ml of the NaOH solution are required to reach the equivalence point? Dr. Lori S. Van Der Sluys Chem Diprotic and Triprotic Acids; Figure out the ratio!!! How much 0.1M NaOH will be required to titrate 10 ml of 0.1M H 2 SO 4? Dr. Lori S. Van Der Sluys Chem

4 ! Theoretical Yield Percent Yield Ch. 3.7 " Quantity of product calculated to form when all of a limiting reagent reacts " Assumes a perfect world; this never happens! Actual Yield " Actual amount of product obtained and measured " Always less than theoretical yield! Percent Yield Dr. Lori S. Van Der Sluys Chem Example: Percent Yield Solid aluminum and gaseous oxygen react in a combination reaction to produce aluminum oxide. In a particular experiment, the reaction of 2.5 g of Al with 2.5 g of O 2 produced 3.5 g of Al 2 O 3. What is the % yield of the reaction? 4 Al(s) + 3 O 2 (g)! 2Al 2 O 3 (s) Dr. Lori S. Van Der Sluys Chem

5 Problem Solving with Gases For a gas, what is the link between the # of moles (n) and the experimental quantities P,V, and T of gas? Example: How many L of N 2 at 735 mm Hg and 26 C are produced from 126g of NaN 3 (sodium azide)? sodium azide gas in an airbag 2NaN 3 (s)! 2Na(s) + 3 N 2 (g) mass P,V,T MW ideal gas law Moles moles Dr. Lori S. Van Der Sluys Chem Spacecraft Atmosphere Lithium hydroxide is used in spacecraft to absorb the CO 2 exhaled by astronauts according to the unbalanced reaction below. What volume of CO 2 at 22 C and 748 torr is absorbed by 1.00 g of LiOH? LiOH(s) + CO 2 (g)! Li 2 CO 3 (s) + H 2 O(l) Dr. Lori S. Van Der Sluys Chem

6 Given the following reactants, predict the products, name the type of reaction, give the balanced molecular equation, and provide the net ionic equation: NH 4 OH(aq) + H 2 SO 4 (aq)! Dr. Lori S. Van Der Sluys Chem Given the following reactants, predict the products, name the type of reaction, give the balanced molecular equation, and provide the net ionic equation: BaCl 2 (aq) + Na 3 PO 4 (aq)! Dr. Lori S. Van Der Sluys Chem

7 Given the following reactants, predict the products, name the type of reaction, give the balanced molecular equation, and provide the net ionic equation: AI(s) + Fe(NO 3 ) 2 (aq)! Dr. Lori S. Van Der Sluys Chem Given the following reactants, predict the products, name the type of reaction, give the balanced molecular equation, and provide the net ionic equation: C 5 H 6 O(l) + O 2 (g)! Dr. Lori S. Van Der Sluys Chem

8 Complexation Reactions! Related to Acid-Base Reactions " Metal cation acts as an acid " Electron-rich molecule or anion (ligand) acts as a base " Metal + ligand forms a complex (can be an ion) ethylenediamine ( en ) [Cu(H 2 O) 2 (NH 3 ) 2 ] 2+ [Cu(H 2 O) 2 (en) 2 ] 2+ " Ligands can bind to the metal in more than one spot (chelating ligand or claw, eg. EDTA, en) Dr. Lori S. Van Der Sluys Chem Example Complexation Reaction CuSO 4 (aq) + NH 3 (aq)! Cu(NH 3 ) 4 (SO 4 ) 2 (aq) 2+ NH 3 H 3 N H 3 N Cu NH 3 Cu 2+ (aq) + SO 4 2- (aq) + NH 3 (aq)! [Cu(NH 3 ) 4 ] 2+ (aq) + SO 4 2- (aq) Dr. Lori S. Van Der Sluys Chem

Chapter 3 & 4: Reactions Part 1

Chapter 3 & 4: Reactions Part 1 Read: BLB 3.1 3.2; 4.2 4.4 HW: BLB 3:1, 11a, b, e, 13 4:19, 24, 39, 49a, c, e, f, 51b, d Supplemental: Rxns:1, 2, 6 11 Know: Chapter 3 Reactions Combustion Decomposition