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calculations on volumetric analysis!

Submitted by meshell on Tue, 09/09/2008 - 22:44

equation:  iodine= vol.(L) of I / total volume(L) in test tube.

Trial 1: volume of 1.0 M iodine solution, mL=2.0

need help in solving the equation. Im not sure what numbers to plug in where.

i think you are missing something between equation: and iodine

Lately there has been a lot of incomplete questions.  I think it may be necessary to make the suggestion that questions should be concise, and provide as much information as possible.  Chemistry problems are a little more complex than just plugging numbers into equations.  The possibilities for any type of problem are numerous and we cannot always guess as to what the missing information may be.  Thus here are my suggestions

1.  If possible type the question as it is on the textbook, exam or laboratory.

2.  Use appropriate units when necessary.

3.  Check your spelling, chloride, chlorine, chlorite, and chlorate, all mean different things.

4.  If the question is a laboratory question, provide background information on what the lab is about.  At least the title, so that we have at least an idea of the subject matter at hand.

5.  If a textbook question, provide the subject area.  Is it a chapter on aqueous solutions or kinetics or thermochemistry.  In most two semester General Chemistry sequences, the second semester is a continuation of more in dept material that was covered in the second semester.
For example if asking "is Pb(OH)2 soluble?".

First semester - No
Second semester - very little but we can calculate the solubility with Ksp.

After all that ,here is my guess.  I am assuming that this is the Iodine clock reaction lab, that deals with rates of reactions.  Based on the above assumption I think the equation is

[I-] = vol I-*[I-]0/total vol

you took 2.0 mL of 1.0M Iodide solution and placed it in a test tube with a buch of other stuff.  You need to add the volumes of all that other stuff to find the total volume.

I have a problem with a question on the topic concerning thermochemistry.

The problem is: How much heat (in kj) is absorbed by a 500g sample of water when it's heated from 44.0 degrees C to 67.0 degrees C? The specific heat capacity of water is 4.184 J/g degree C.

Okay, I don't know which equation to use for this problem. I was thinking that since this appears to be a specific heat problem that I should use the equation: J/g x degree Celsius.

Is this the right equation to use? Furthermore, do I have to change 4.184 J/g degree Celsius into moles?

Basically, how do I start?

Thanks in advance.