Determine the Enthalpy change in hydration of Anhydrous Magnesium sulfate (MgSO4)

[Kurstd]

MgSO4+C3H8O yeeuh yeeuh. did i almost kill myself or what?

[Kurstd]

I cooked Epsom earlier, and mixed it with water to see what would happen, and nothign did, but when i got bored and mixed it wit alchohol, it got almost 110*F.

Why? did i heat it to much and creat this Sulfur Trioxide biproduct? or is it normal.

just wondering it was kinda wierd but cool

[Tyr360]

@Feligatre99 You're an idiot. This is a thermochemical experiment, if he didn't cover it up, his errors would have been huge.

[hey2008hey85]

i tried doing this experiment by mixing 0.1moles of CaCl2 with 100ml of water and i got no temperature change or heat released.

there was nothing wrong with the thermometer but i did use tap water

will tht make a difference?

also where did u get tht value of -104kj/mol for MgSO4

[SumayahsIslam]

we did a similar experiment in a chemistry lab class. i hate enthalpies, probably cos I wasn't listening to the teacher while she explained it :S my bad lol

[SumayahsIslam]

I hate thermodynamics in general and drawing born haber cycles has been the most boring part of chemistry, apart from that everything else is ace.

[wing0304]

I did this experiment in my Chemistry lesson last week also :D

[evansp12]

Very nice video, and well presented! 5*

[11to]

can you try todo flame test with it?

[Cforchemistry]

Do you mean to make a video about flame test?

[11to]

yes

[Zoetepasweiden]

Simple, but good.

Rating: 5 stars!

[bigstrontium]

Good work with a very simple equipment. I like that.

[cobrasniper555]

Good job mate! This video was interested and educational for me. Not exactly my field (thermodynamics) but I like your work!

[ytmachx]

Well done CforC

[bla287]

Very nice one, don't worry about the results, even in the student lab at uni, errors of such dimension are quite common (they won't let us use the really expensive stuff ;))

But for suggestions concerning improvement, this comes to my mind:

-Make the ratio volume/surface as big as possible, by using bigger quantities and/or making length/height/width of the solution as similar as possible => heat exchange will be reduced

(cont)

[bla287]

(cont)

-Use a metallic thermoelement with digital meter, they're usually smaller, faster, more accurate and take/give away less heat from the sln

(cont)

[Cforchemistry]

apparatus is really important in my case, I will try finding a better calorimeter or a digital thermometer for my next trial.Thanks for your ideas!

[bla287]

(cont)

-A more complicated issue is dilution:

A highly conc. MgSO4 sln has a different heat capacity than H2O, but the error thereof becomes smaller on higher diln. Also, higher diln leads to less ΔT => less heat exch. And: the reaction between MgSO4 and pure H2O has another (higher) enthalpy than the reaction of MgSO4 and an already partially saturated MgSO4 sln.

On the other hand, the smaller ΔT, the higher is the relative error of the temp. measurement

(cont)

[bla287]

(cont)

=> You have to find a golden middle between the neg. effects of too high concentration and the neg. effects of the temperature measurement inaccuracies that rise with falling conc, but I have no idea on how to exactly calculate that :D

That's all I can say for now, keep up the good work!

[Cforchemistry]

I had a hard day in calculating the enthalpy of it, and I look up inorganic handbook to find specific heat capacity data of MgSO4 sln.

[bla287]

There is actually data on heat capacities of solutions? Lol, never knew that ;) But keep in mind that the concentration is steadily changing during the dissolving process => you have to integrate, approximate etcetc... so if I did the experiment, I'd just work with lower concentration and simply calculate with the heat cpcty of H2O :D

[Socoolscienceshow]

That was definetly pretty awsome 5*

[Cforchemistry]

thanks

[phj1990]

That's the way to do it!

But don't expect to get the answer exactly right unless unless you're using a professional calorimeter.

These temperature measurements are prone to small errors.

Don't use a magnetic stirrer by the way, or use it briefly, because all the energy of rotation will be transferred to the solution in the form of heat.

[Cforchemistry]

There is always pros and cons in using magnetic stirrer, I will try experiment with and without it to see the difference, and find a better calorimeter. Thanks for your comment in advance!

[chemdog8]

Suggestion: Use a magnetic stir bar and keep the thermometer in the solution continuously. Add the solid using weighing paper (it's slippery). The vortex created by the stir bar will keep the solid from sticking to the sides of the beaker, and you'll get more accurate results. To get the Delta-T, extrapolate the temperature before and after the addition back to t=0 (time of addition of the salt).

[Cforchemistry]

It is very constructive idea, I was thinking of using magnetic stirrer at first, but the cup is just too thick, so I have to find a way to do so.Thanks for your comment!

[chemdog8]

If you use the double extrapolation method to determine Delta-T, then the insulation becomes less important to the measurement, especially for small temperature changes. Just use a regular beaker.

[farhmoha]

Nicee stuff I never really considered parallax before but now I will only read with one eye.

[Cforchemistry]

Parallax error usually mean you didn't take reading at eye level, not really necessary to read with one eye.

[KMnO4dalla]

Nice:) good vid!

5*

[Cforchemistry]

thanks