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Unformatted text preview: CHEM 210
FINAL EXAM’ 4/25/05
NAME: l. (30 POINTS) (a) Suppose that you are using 0.100M NaOH to titrate a 20.00 mL
solution that contains an unknown mixture of HCl and H3PO4 and that you obtain two
endpoints — the ﬁrst after adding 10.15 mL and the second after adding,7.85 mL more.
Calculate the molarities of H01 and H3PO4 in the unknown. SHOW YOUR WORK. (Formula Weights: NaOH, 40.00 gin/mole; HCl, 36.46 gm/mole; H3P04, 98.00 gm/mole) (b) When performing this experiment, a student analyzes his/her titration plots and
concludes that the ﬁrst equivalence point occurred after adding 5.50 ml of NaOH and the
second occurred aﬁer adding 12.22 mi more. After lab, lie/she asks the professor to
“check the results”. Without even using a calculator, the professor sadly informs the
student that these results are not possibly correct and that this experiment will
undoubtedly need to be repeated. Brieﬂy but clearly explain how the professor was able
to reach this conclusion. 2. (24 POINTS) Match the following titration reactions with the plots that you would
expect each to exhibit: ' (b)
45' 50 mL titrant
.95 5‘0 1) 50 mL of0.10M HCI with 0.10M NaOH - 2) 25 mL ofO. 10M NaOH with 0.10M HCl -
3) '25 mL of 0. 10M H3PO4 with 0.10M HCl ' - 4) 25 mL of 0. 10M Neal-11°04 with 0.10 M NaOH - 3. (20 POINTS) What is a “polyprotic acid”? Give three speciﬁc exampies. 4. (28 POINTS) (3) Outline, in block diagram form, the principal components of an
atomic absorptiOn spectrometer (AAS). i (b) What kinds of analytes is AAS well suited for? What kind of chemical information
samples does AAS not provide? 5. (28 POINTS) (a) Outline, in block diagram form, the principal components of a gas
chromatography (GC) instrument. (b) In general, what kinds of analytes is GC well suited for? For what kinds of samples is
GC not well suited? 6. (20 POINTS) What is the Nemst equation? Deﬁne all terms (including units). ...
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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.
- Spring '07