[pure-silver] Re: Basic Chemistry
- From: Laurence Cuffe <cuffe@xxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 12 Jun 2008 20:08:54 -0700
As a theoretical chemist, I'm perfectly happy with this solution, as a lab rat
I'd point out that the time to reach the given temperature is, in principle,
infinite!
I'd use higher or lower temperatures than described and monitor the temperature
of my target solution until it got there. Back to the original question
solutions should warm up or cool down with equal facility, however its much
easier to get water a lot higher than your target temperature than to get it a
lot lower. One other trick, if you want to speed things up use a reseal-able
plastic bag to hold your solution, it gives you a larger surface area and a
much thiner barrier between the two liquids.
All the best
Larry Cuffe
ps. I don't want to knock Nicholas's solution, I've always been impressed by
his contributions, and in this case I was also impressed by the speed with
which he produced it.
On Thursday, June 12, 2008, at 05:24PM, "Nicholas O. Lindan"
<nolindan@xxxxxxxxxxxxx> wrote:
><eroustom@xxxxxxxxxxx>
>> I use a hot bath to put my bottles of working
>> solutions in to bring them to temp.
>
>> If my solutions are all at basement temp of
>> 60 to 64F, what should the hot bath be at to
>> bring everything to 68-70F. 1 Liter glass
>> bottles (usually full). 6 Liter tub of water.
>
>Well, in typical high-school chemistry fashion:
>
> Neglecting the thermal effects of the bottles
> Assuming everything is in a perfectly insulating container
>
> Aq + Br + Cs = T * (A + B + C)
>
> A, B, C ... are the volumes
> q, r, s ... are their initial temperatures
> T is the final temperature
>
>Which should be sort of obvious, if you
>think about it.
>
>For a bottle (vol. A, temp q) in a water bath
>(vol. B, temp r), the temperature r at the start to
>reach a final temperature T should be
>
> r = [(A / B) * (T - q)] + T
>
>or: r = [(the ratio of the volumes)
> times
> (the difference in temperatures)]
> plus
> the final temperature
>
>Not a bad thing to tape to the wall.
>
>For one bottle:
>
> The volume ratio is 1:6
> The temperature difference is 68F - 62F = 6F
> The final temperature is to be 68F
>
> r = 1/6 * 6F + 68F
> = 70F water bath
>
>For 3 bottles the volume ratio is 3:6,
>the student can calculate the temperature.
>Quiz next Tuesday.
>
>In real life things will be different: you have a flow of
>heat to the air, the water bath container, the lab bench,
>the glass bottle, and you are loosing heat to evaporation,
>gaining heat from your stirring, loosing heat to warming
>the chemicals in the bottle (don't forget to use the
>volume of the water _before_ the chemicals were mixed in)...
>
>Experiment and making a table will be the fastest and
>most accurate method. Which is also sort of obvious.
>
>==
>Nicholas O. Lindan
>Cleveland Engineering Design, LLC
>Cleveland, Ohio 44121
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