210exambs07 - Wm.wu———— CHEM 210 FINAL EXAM 1...

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Unformatted text preview: Wm.wu———— CHEM 210 FINAL EXAM 1 1/27/06 NAME: 1. (30 POINTS) (a) Suppose that you are using 0.050M NaOH to titrate a 25.00 ml solution that contains an unknown mixture of H3P04 and HCl and that you obtain two endpoints - the first after adding 19.15 ml and the second after adding 17.85 ml more. Calculate the molafities of HCl and H3P04 in the unknown. SHOW YOUR WORK. (Formula weights: N'aOI-I, 40.00 g/mole; HCl, 36.46 g/mole; H3P04, 98.00 g/mole) (b) Suppose that you notice that a fellow student titrating his/her unknown performs a similar titration but obtains only one endpoint. Even though you can’t see the endpoint _ volume, what can you conclude about this unknown? 2. (24 POINTS) Match the following titration reactions with the plots that you would. i expect each to exhibit: . m] titrant '95- o ’7 I ml titrant ml'titrant 100 (e) (f) NONE OF THE ABOVE. pH m'l titrant 05' I no 1) 25 ml of0.]0M BC] with 0.10M NaOH - '_ 2) 50 ml of 0.10M NaOH with 0.20M HCl - 3) 25 ml of0.10M H3P04 with 0.10M HCl - 4) 25 ml of 0.10M Na2I—IPO4 with 0.10 M NaOH - 3. (20 POINTS) A buffer solution is one whose pH does not change very much even when significant amounts of acid or base are added to it. What two species must be" present in a buffer to allow it to resist such pH changes? Why? 4. (32 POINTS) (3) Outline, in block diagram form, the principal components of an atomic absorption spectrometer (AAS). - . - rmmmflw mw—fl-um—u—m .-.--.—..— (b) What kinds of analytes is AAS well suited for? What kind of chemical information samples does AAS not provide? - (c) What is Planck’s equation? What is meant by the term “quantization”? 5'. (24 POINTS) (a) Outline, in block diagram form, the principal components of a gas chromatography (GC) instrument. 0’) 111 general: What kinds of analiztes is GC well suited for? For what kinds of samples is GC not well suited? . . 6. (20 POINTS) Show clearly how you would prepare 200 ml of a 50 ppm K solution from: a) a 200 ppm K stock solution. b) solid KC] (formula weight of KCl = 74.55 g/mOle; atomic weight of K = 39.10 g/mole; atomic weight of C1 = 35.45 g/mole). . mm_—.___ ...
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This note was uploaded on 09/12/2008 for the course CHEM 209 taught by Professor Greg during the Spring '07 term at University of Louisville.

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210exambs07 - Wm.wu———— CHEM 210 FINAL EXAM 1...

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