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### Topic: [Help] Questions about one-tailed tests and solubilities  (Read 3496 times)

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#### eigen

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##### [Help] Questions about one-tailed tests and solubilities
« on: April 23, 2011, 02:54:17 AM »
I have a few questions I was wondering if you guys could help me with. You don't need to solve them, I just want a push in the right direction so I can understand them. Any and all help is appreciated!

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1. A technician obtained the following results for the concentration (mg/dL) of cholesterol in a blood sample: 240, 252, 242, 238, 239, and 236. The technician re-measured the cholesterol in the same blood sample using a different method. The results were: 233, 231, 222, 235, 239, and 234. At the 95% confidence level is the second method consistently less precise?

I'm pretty certain I need to use a one-tailed F-test for this, but I simply don't know how to do that while comparing with the second method. Any thoughts?

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2a. The Ksp of cerium(III) iodate is 1.4×10-11. What is the molar solubility of cerium(III) iodate in pure water?

I calculated a value of 0.00085 M. I'm fairly certain this is correct.

2b. What concentration of sodium iodate in solution would be necessary to reduce the cerium concentration in a saturated solution of cerium(III) iodate by a factor of 10 below that calculated in part a?

I'm not sure where to start with this one. I can't just change the molar solubility by dividing it by 10, substituting it into the Ksp expression, and solving for [IO3-]. Any ideas/hints?

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3. A solution is prepared by adding 100.00 mL of 0.10 M AgNO3 to 100.00 mL of 0.12 M NaCl. (At 25 oC, the Ksp for AgCl is 1.8×10-10.) Calculate the number of milligrams of Ag+ that is not precipitated.

I flat out don't know where to begin on this one.

#### MichelleMyBelle329

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##### Re: [Help] Questions about one-tailed tests and solubilities
« Reply #1 on: April 24, 2011, 03:28:10 PM »
We are in the same chem class lol. I'm working on the quiz now. it sucks.