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Warmup

Warmup.

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Warmup

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  1. Warmup Happy Friday WSCA! Today there is a lot going on around the campus. Today is a "Fun Friday". Any student who has not received two or more tally marks during Academic Lab and Core Advisory this week, and has not missed MASH this week, is invited to join Mr. Crosson on the outdoor blacktop during CA today. Core Advisory attendance will be taken in the room of your check in teacher, not the gym today. Please go to your CA teacher's room for attendance. Also, today is the WSCA and Rocklin Academy science fair. 7th and 8th graders are to be here by 6:30pm for their interviews tonight. If science fair participants are not staying until 8:30pm (the end of the science fair) you MUST make arrangements for your project to be taken home. The school is not responsible to clean up your project. Please make arrangements. This next Monday the 14th is the Spring Music concert and art show. Please come out and support these wonderful programs. Also, remember that year books are currently on sale! Here is today's SAT question of the day: The sum, product, and average (arithmetic mean) of three integers are equal. If two of the integers are and , the third integer is? Answers: −5, 0, 2, 5 

  2. Warmup • On a piece of paper, jot down the official title of your project, and choose a category. • Choices: • Physics • astronomy, electricity, motion, energy, force, engineering stuff • Chemistry • batteries, combustion, acids and bases, plastics • Biology • ecology, cells, heart rates, metabolisms, sports physiology • Behavioral Science • personality, thinking speeds, perception, making choices

  3. Warmup Before] the end of the semester, [each of you] [needs] to meet with your adviser [or I] to discuss your plans for next year. Before each of you needs or I No error 

  4. Warmup Solve for x: In a community of people, each person owns a dog or a cat or both. If there are dog owners and cat owners, how many of the dog owners own no cat? If the pH is 11, what’s the [OH]? logx 900 = 4 10x = .003 Write a chemical equation for the disassociation of the Arrhenius acid, H2S in water. (Hint: this is a diprotonic acid!) Then setup the expression(s) through which you’d calculate its disassociation constant.

  5. MARCH 2, 2011 pH Titrations References: http://library.thinkquest.org/C006669/data/Chem/equilibrium/ka.html http://www.chembuddy.com/?left=BATE&right=dissociation_constants

  6. Concept Review

  7. Bases Disassociation Constants List The values listed are pKa’s, not Ka’s. 10^-pKa = Ka

  8. Practice: Writing Equations For each problem, write the balanced chemical equation for each disassociation or neutralization reaction. Also setup the equation for the equilibrium constant. 1) HCl 2) NaOH  3) NH3 + H20  4) CH3COOH + NaOH  5) H2SO4 + NaCO3 

  9. Practice:Preparing a solution with a certain pH How many grams of NaOH should be added to roughly 1L of water to produce a pH of 11? a) Find the [OH-] that corresponds to a pH of 11. b) Find the disassociation constant. c) Write the disassociation equation for the correct [OH-], and solve for the total number of moles needed of NaOH. d) Use dimensional analysis and molecular mass to convert moles to grams.

  10. Practice:Titration with an unknown You have 100mL of HCl, of unknown concentration (Molarity). You add 200mL of .1M NH3, at which point the pH is neutral. • Assuming both solutions fully disassociate, how concentrated was the HCl? • Assuming the HCl fully disassociates but the NH3 does not, how concentrated was the HCl? (Ammonia’s pKa is 4.75)

  11. Titration Pre-lab Group 1 Titrate water using an acid. Group 2 Titrate water using a base. Group 3 Titrate the buffer solution using an acid. Group 4 Titrate the buffer solution using a base. Titration curve of control group. Titration curve for buffer effectiveness.

  12. Titration Pre-lab What indicator dye’s will the acid groups agree to use? What indicator dye’s will the base groups agree to use? How should the concentrations of each solution be setup? (do math!) acetic (ethanoic) acid CH3COOH pKa = 4.75 hydrochloric acid HClpKa = -4 sodium hydroxide NaOHpKb = 0.2

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