Possible ideas for inorganic chemistry projects

Lukraak_Sisser

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As part of a class I'll be teaching this year I introduce high school students of 15-16 year old to the basics of inorganic chemistry. (Salts, crystal water, solubility vs temp of solution, acid/base interactions and crystallization)
The methods and theory I've given a few years now and are for me quite satisfactory, but I'm wanting to not end it with a normal graded test.
It's my intention to give them +/- 10 hours in groups of 3-4 spread over a week (I have that time available) to do a project in which they apply (parts of) the theory and give a report on which I can grade them. Of course their practical actions are also part of the grade.

They will have access to the chemistry classroom and they are quite proficient in basic equipment such as Bunsen burners.
I have a number of projects they could try to crack in mind, but maybe some people here have ideas that could help me out. The idea is that it is doable, but it should be challenging.
I don't really care whether they succeed, but that they show the ability to apply the given theory experimentally and learn from their errors.

Some idea of projects I have in mind are:
Try to develop a method to determine as best as possible the types and amounts of salts in a sample (soil/water/food/etc)

Measure the carbonate and phosphate content of a soft drink as accurately as possible

Try to get large and unbroken crystals from a salt that dissolves exothermically

Find a way to layer a metal on top of a different metal in such a way that it sticks using a salt solution.
 
Lukraak_Sisser said:
As part of a class I'll be teaching this year I introduce high school students of 15-16 year old to the basics of inorganic chemistry. (Salts, crystal water, solubility vs temp of solution, acid/base interactions and crystallization)
The methods and theory I've given a few years now and are for me quite satisfactory, but I'm wanting to not end it with a normal graded test.
It's my intention to give them +/- 10 hours in groups of 3-4 spread over a week (I have that time available) to do a project in which they apply (parts of) the theory and give a report on which I can grade them. Of course their practical actions are also part of the grade.

They will have access to the chemistry classroom and they are quite proficient in basic equipment such as Bunsen burners.
I have a number of projects they could try to crack in mind, but maybe some people here have ideas that could help me out. The idea is that it is doable, but it should be challenging.
I don't really care whether they succeed, but that they show the ability to apply the given theory experimentally and learn from their errors.

Some idea of projects I have in mind are:
Try to develop a method to determine as best as possible the types and amounts of salts in a sample (soil/water/food/etc)

Measure the carbonate and phosphate content of a soft drink as accurately as possible

Try to get large and unbroken crystals from a salt that dissolves exothermically

Find a way to layer a metal on top of a different metal in such a way that it sticks using a salt solution.
Click to expand...

Sounds good - I will see if I can pull some that don't use naughty chemicals (mercury, sodium, lithium (etc.), Unless you are good with those:D!!
 
Could have a group trying the experiment that made Avagadro famous (to us at least) - even though he did not do it!!!
 
fuelair said:
Sounds good - I will see if I can pull some that don't use naughty chemicals (mercury, sodium, lithium (etc.), Unless you are good with those:D!!
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Preferably nothing more toxic than lead :)
I'm sure parents would complain if I have to tell them their child is broken, can I have a new one please?
 
Lukraak_Sisser said:
Preferably nothing more toxic than lead :)
I'm sure parents would complain if I have to tell them their child is broken, can I have a new one please?
Click to expand...
Damn I was about to suggest cyanide making, it's highly instructive and pretty simple with only household chemical. Oh well...
 
My early 1960's Gilbert chemistry set taught me how to make gaseous chlorine. I suppose you don't want to reproduce that one.
Or there's the old "hold a test tube under water, bring it closed-end-up above the surface, and introduce a bit of sodium". Then see what happens if you let a bit of air in. That happened to the high school chem class one period before mine. We weren't allowed to do it.
 
Trebuchet said:
My early 1960's Gilbert chemistry set taught me how to make gaseous chlorine. I suppose you don't want to reproduce that one.
Or there's the old "hold a test tube under water, bring it closed-end-up above the surface, and introduce a bit of sodium". Then see what happens if you let a bit of air in. That happened to the high school chem class one period before mine. We weren't allowed to do it.
Click to expand...

I've done the chlorine as a controlled experiment in a fume hood, but the thing is, the reaction is interesting and somewhat spectacular, but not really a technical challenge. It's also more a reaction for the electro chemistry classes they'll get a year later as it's redox and not acid-base.

Sodium is spectacular too, but again, not that much of a challenge and again to try and understand it electrochemistry is needed.

One other they'll get to do is try and make coloured fireworks. In the theoretical course they get taught the basic recipe for gunpowder and they'll have seen that burning certain salts give pretty colours. So every year they come up with the idea of mixing the two. However, adding a fourth component to the basic recipe means you get a non-flammable mixture. Trying to overcome that by looking WHY that happens and how you can prevent it is a nice brainteaser.
 
Trebuchet said:
My early 1960's Gilbert chemistry set taught me how to make gaseous chlorine. I suppose you don't want to reproduce that one.
Or there's the old "hold a test tube under water, bring it closed-end-up above the surface, and introduce a bit of sodium". Then see what happens if you let a bit of air in. That happened to the high school chem class one period before mine. We weren't allowed to do it.
Click to expand...
Ah the fun I had with a car battery charger, a few big lead-acids and a warm brine solution...
 
For visual impact and relatively low toxicity you might consider opening up light sticks and performing the luminescence reaction in a glass flask, etc. Pouring the glowing liquid from one container to another is very dramatic. The only problem is that to my knowledge, one of the components in light sticks is an organic with a phenolic ring. Perhaps there are luminescent reactions which are more purely inorganic if this is a problem.

Same is true of the Briggs-Rauscher reaction, which yields a beautiful oscillating visual chemical change but requires one organic "enolic" compound.

You could dissolve chemicals in water that are exothermic or endothermic (e,g, ammonium nitrate) when they enter solution to show the different temperature changes.

Always nice, if requiring a bit of caution: very small amounts of thermite, or of zinc powder mixed with sulfur and lit with a fuse, or a very small lump of sodium or potassium metal placed in water. If one uses small quantities (much less than a gram), do the reactions on non-flammable surfaces (sand is good) and keep the students way back, I don't think that anything or anyone will break. Just if the reaction doesn't do anything at first resist the urge to approach it to fix it- putting your face over it will serve as a catalyst for some reason. The sodium in water releases hydrogen gas and may explode, so avoid a glass container and wear eye protection.

As in any recommendation, don't count on what I post here to include all the safety precautions or risks. But I think (IMHO) the risks are less (if done correctly) than the risks involved in the students being driven to school that morning.

I'll keep thinking of demos I've seen.
 
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A chain of copper compounds is always fun. Copper metal -> copper nitrate -> copper hydroxide -> copper oxide -> copper chloride -> copper carbonate -> copper acetate -> copper aspirinate.
 
Lukraak_Sisser said:
...
The methods and theory I've given a few years now and are for me quite satisfactory, but I'm wanting to not end it with a normal graded test.
It's my intention to give them +/- 10 hours in groups of 3-4 spread over a week (I have that time available) to do a project in which they apply (parts of) the theory and give a report on which I can grade them. Of course their practical actions are also part of the grade.
.
Click to expand...

If you're going to give them -10 hours I'd suggest purifying thiotimoline.
 
Madalch said:
A chain of copper compounds is always fun. Copper metal -> copper nitrate -> copper hydroxide -> copper oxide -> copper chloride -> copper carbonate -> copper acetate -> copper aspirinate.
Click to expand...

That one might be doable, I'll have to see if they've understood the theory enough to figure out how to make such a chain, but it should be possible.

As for the demo idea's they are great and I'm sure I could use a few, but the idea is that they try and tackle a problem themselves using what they know by then.
They have good skills, but I'm still not comfortable with them handling pure sodium for some reason :)
 
It sounds like great fun to take your chemistry class.

I think this doesn't exactly fit your criteria for a class experiment, but I was about to embark on a little chemistry experiment of my own.

Last year, we went backpacking and cleaned up our dishes using some water that we had treated with iodine tablets. The water turned dark blue. This was the water we had been drinking and it was a bit gross to see that the water we had been drinking could turn in to something that looked like ink.

I experimented with it a bit when I got home but I wasn't able to reproduce the same effect although I might have worked at it a little bit more by trying higher concentrations of iodine or maybe something else to represent the dirty dishes (I used cooked oatmeal).

We took a trip this year to near where we had camped and we had access to the same stream although somewhat below the place where we had camped the previous year. I collected some water and have brought it home and plan to compare the reaction of the water from the stream with iodine tablets dissolved in it to the reaction of the water from our tap. I know from the internet that iodine and starch will turn blue, but the reaction seemed so much more intense with the water from the stream than with water from home. What I am going to try to find out is whether there was something in the water from the stream that makes the reaction stronger or whether the experiments I did last year just didn't duplicate the conditions when we washed the dishes with the stream water. The stream water is glacier melt and is filled with suspended ground granite. The stream water probably also has a fair bit of organic matter dissolved in it.
 
Iodine produces the blue colour in the presence of starch (well actually amylose). It's the classic test for starch, and same reaction that those dubious "counterfeit banknote detector" pens use
 
I've run the experiment two times with two different classes and I'm happy to say things went quite well. I do have tweaks to make, especially to deal with classes of different levels of abilities, but all in all a success.

The first class I gave 6 projects for groups of 4.

Isolating salts from food (solid or liquid)
These projects went ok ish, but they were hard to quantify for the pupils. They did branch out into trying to discover what other ingredients they could discover, but I adapted the project for the second class.

Identifying a series of unknown salt solutions.
In theory the easiest to do given the theory I gave them, but in practice the project did not fire their imagination at all, causing them to lose interest and thus not actually thinking about things. I managed to keep them working and they did get some results, but not the self study I tried to achieve.

Quantifying Phosphate / Carbonate content in soda (cola). This project on the other hand was well received. They tried various methods (boiling things dry, precipitation, neutralization and combinations) over the week and although they did not manage to get a clear answer, they actively attempted to use their theoretical background to think up new steps.

Creating good crystals.
Again, this project was well received. They quickly discovered that oversaturating a solution give easy but small crystals. After some experiments they decided to use a quickly crystallizing salt as primers to attempt to crystallize copper sulphate. This gave them a nice set of hybrid crystals about 10mm long and 2-3 mm wide, where the two salts clearly gave separate forms.

Coloured gunpower.
As expected pupils like this project and they worked hard. They tried various combinations and recipes and although they never managed to actually give it a colour, they did manage to discover the recipe for flashpowder by adding magnesium powder.

Given the feedback of the pupils and their reports I altered the projects for the second run to prevent groups not bonding with their projects.

Quantifying phosphate/carbonate remained and this group chose a radically different approach, focussing on the carbonate. Their main idea was looking up the saturation table for sodium carbonate, then measuring how much solid sodium carbonate they'd have to add to the soda to discover how much carbonate originally was present. Since carbonate in an acid dissociates they eventually discovered that they needed to neutralize things first. They also isolated as much salt as they could and managed to get some form of pretty feather shaped crystals.

I changed the isolating salt from foods to specifically isolating and identifying salt from cup a soup. The group decided to get rid of insolubles first and then doing various precipitation experiments. Once they had a working method on simple clear broths I gave them a series of different soups and they discovered that their method did not work on all. From there they decided to try to analyse various components by trying to create clear broths.

I gave two gunpowder projects. One was coloured gunpowder again, the other was an attempt to create sparkle sticks like you give to children. The group with the coloured gunpowder ran into the same problems as the first group, and independently managed to create flash powder. The ones making the sticks actually managed to find a way to crudely attach a gunpowder / magnesium mixture to a steel wire and get it to burn and give sparks. They did discover the hard way that changing the recipe by "only" 5% actually makes a difference.

I split the crystals into two groups as well. One group had to make crystals from a single salt, the other specifically by using two or more salts. The single salt group experimented with various mechanisms and eventually managed to make a large crystal about 4 cm long and 2 cm wide of copper sulphate. The group using multiple salts unfortunately consisted of three pupils barely contributing, but the one actually working did manage to get some smallish crystals.


I do need to put constraints on the amount of materials they can use, and for groups in classes that have more problems with chemistry I need to create a set of pre-made forms they can use to give themselves a structure to work with, but for the most part the pupils were actively using either the class-taught theory or voluntarily using chemistry textbooks or sites to try and tackle these problems.
 
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