Week 5 Chemistry Notes
Week 5 Chemistry Notes CHEM 1127Q-011
Popular in General Chemistry
verified elite notetaker
Popular in Chemistry
This 3 page Class Notes was uploaded by Amelia on Wednesday September 28, 2016. The Class Notes belongs to CHEM 1127Q-011 at University of Connecticut taught by Dr. Cady in Fall 2016. Since its upload, it has received 17 views. For similar materials see General Chemistry in Chemistry at University of Connecticut.
Reviews for Week 5 Chemistry Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/28/16
9/26 Chapter 4 Stoichiometry and Chemical Reactions Chemical Reactions 1) What are chemical reactions? a) When two or more substances interact with each other to form something new b) There are dozens of different classifications of chemical reactions c) Rather than classify them by how reaction happens sometimes classify by what happens. 2) Evidence of chemical reaction a) Precipitation solid formed from a clear solution (cloudy) b) Gas evolution gas bubbles appear c) Give off heat or light d) Change in temperature or energy e) Change of odor 3) Balancing chemical reactions a) Everything in reactant has to end up in product. b) Reactant(s) → Product(s) c) Example: i) C3 8 2CO +H O2 2 ii) C3 8 23CO 2H 2 iii) C3 8 2CO +4 2 H2 iv) C3 85O 2→3CO 2+4H O2 4) Solubility and compounds dissolved in water a) Many Ionic compounds dissolve in water… but some don’t b) If things dissolve they are soluble c) If things don’t dissolve they are insoluble d) Water stabilizes Ions, makes them split from their pair to “hang” with water molecules 5) Precipitation Diagram a) Table 4.1 in book shows what normally does and does not dissolve, plus exceptions i) Anything in group one is soluble ii) Some halide atoms (Cl, Br, I) but not all. iii) Acetate, bicarbonate, nitrate, chlorate and most sulfates. iv) Compounds containing carbonate, chromate, phosphate, and sulfide ions are not usually soluble . Also hydroxide ions . v) Check the book for this one! 6) Net ionic equation a) Just like a chemical equation only we show all the ions separately and then eliminate ones thats are inactive/do not react. b) The ones that react are called spectator ions. c) Note the (aq) dissolved in water 9/28 Exam 1 Review Office Hours Thursday 11:3012:30 A405 BRING: A pen (black or blue), #2 pencil, and ID Grades are 5050 multiple choice and long answer 19 multiple choice questions and 10 ‘long’ answer 1) An unknown element (X) forms a compound with the formula XBr . If the compound contains 3 81.1% Br by mass, what is the molar mass of the unknown element? What is the identity of the element? a) Assume 100g, so Br is 81.1g b) 100g 81.1g → 18.9g X c) 81.1g/79.90g/mole = 1.015moles Br d) 1.015moles Br × 1X/3Br = 0.338moles of X e) 18.9g/0.338moles = 55.917g/mole f) 55.917g/mole → Fe, Iron g) FeBr 3 2) When 2.56 grams of iron is heated in air it forms an oxide that weighs 3.66 grams. What is the empirical formula or iron oxide? a) Fe O x y b) Fe → 2.56 grams c) 3.66g (FeO) 2.56g (Fe) = 1.10g (O) d) Fe: 2.56g/55.85g/mole = 0.04588moles Fe e) O: 1.10g/15.999g/mole = 0.06875moles O f) 0.06875moles/0.04588moles ≈ 1.5×2 = 3 g) 0.06875moles/0.06875moles ≈ 1×2 = 2 h) Fe O 2 3 3) You have a stock solution containing 0.650M AlCl . You add the prope3amount of this stock solution to a beaker to create 500mL of a 0.250M Cl solution. How much water do you have to then add to the solution to attain proper volume and concentration? a) Start: 0.650M/L of AlCl 3 b) Goal: 500mL of 0.250M Cl c) 0.650M/L of AlCl × 3Cl/13lCl = 1.95M Cl3 d) 1.95M(L) = (500mL)(.250M) e) L = .0641 or 64.1mL f) 500mL 64.1mL = 436mL H O added 2
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'