chemistry, Crafty, Experiments, Together with sis

MEL Chemistry Experiments: Making Batteries

We did two more experiments a couple days ago: Liquid Wires (creating a simple circuit using graphite and liquid glass, a sodium silicate solution) and making our own Zinc-Carbon Battery, a chemical source of electric current that relies on an oxidation-reduction (redox) reaction between manganese dioxide (MnO2) and zinc (Zn). 

A redox reaction involves the transfer of electrons from one element (the reducer) to another element (the oxidizer).

Our battery is divided into two sections, separated by wadding: one section holds the oxidizer MnO2 and the other contains the reductant Zn. When the crocodile clips are connected to a diode, the circuit is closed and the reaction can begin: electrons start migrating from the zinc section to the manganese section (manganese dioxide mixed with graphite o make it a better conductor). We used ammonium chloride NH4Cl as the electrolyte.

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MEL Chemistry Experiments: Flames and Minerals

Monday was a chemistry day as we went to the post office to fetch our brand new delivery from the MEL Science subscription! We set a record of 6 chemistry experiments in one day! We just couldn’t stop, maybe because all of the experiments involved fire.

We started with the Minerals box. The first experiment was about heating up some semiprecious stones, amethysts (a species of quartz widely used in jewellery). The nature of amethyst’s color is still a mystery: some theories suggest that the color is of organic origin because it changes when amethyst is heated. Our purple amethyst became completely white after we heated it!

Simon watching the solid fuel burn (C6H12N4 – hexamethylenetetramine)
solid fuel C6H12N4 – hexamethylenetetramine – burning with the amethyst wrapped in aluminium foil on top of the flame diffuser
Amethysts in their original color
Amethyst has become white

We also repeated the same experiment with a piece of red coral.

Chemically, coral consists almost entirely of calcium carbonate CaCO3—the same compound chalk is made of (plus the red pigments known as carotenoids). When coral is heated, a strong smell should arise, because of the organic remains left in the skeletal structure. We didn’t really smell much, the coral seemed unchanged after heating:

What we did next was dissolve some malachites! We used NaHSO4 (sodium hydrogen sulfate) as an acid that the mineral would react with and heated the solution up to speed up the process. The big question was: will the malachites dissolve? And will a certain metal come free as a result?

Pieces of malachite in a beaker
The solution turned blue when heated
We added K4[Fe(CN)6], or potassium ferrocyanide, to the solution to detect metal ions. The indicator substance turned brown, which indicates copper ions!

Malachite is a mineral that contains copper Cu! In fact, malachite consists of (CuOH)2CO3 – basic copper carbonate. This compound has been used as a source of pure copper since antiquity, the MEL Science website explains. 

What was left of the malachites

Now it was high time for some fireworks!

This one was our favourite! We performed it many times, just to see the mesmerising green sparkles. All one has to do is dip a stick in paraffine, then in CuSO4 (copper(II) sulfate) for 30 seconds, then in paraffine and (very briefly) in water. This creates a kind of homemade sparklers, like the ones popular on New Year’s Eve, spitting spectacular flashes of green.

What made the flame green is its copper Cu2+ component. Metal ions such as copper ions Cu2+ can emit light of a certain color when heated to high temperatures. Copper emits green, while rubidium Rb creates red and sodium Na creates yellow, and so on. You can create colorful fireworks, but you can also detect which metal is present in a sample by examining the color of the flame.

What else should we burn? Magnesium! Because it lights up so pretty:

From a chemistry perspective, burning is the process of giving electrons to oxygen O in the air, releasing a lot of heat and light. One of the most obvious trends in the periodic table is that the elements on the left side of the table are generally more willing to give electrons away than the ones on the right. But, as we learned from our last experiment called Rocket Fuel, not only oxygen can take electrons from the fuel, in other words, there are other substances that can act as the oxidant (the substance that wants to take electrons from the fuel). If you want your fuel to burn without air, you have to include your own oxidant too. This is how space rockets work.

In our experiment, we mixed the oxidant, calcium nitrate Ca(NO3)2 and the fuel, potassium ferrocyanide K4[Fe(CN)6] that doesn’t burn very well in air (used as fuel for small model rockets and fireworks), and heated them up. When we later set the mix on fire, it didn’t quite produce the effect we had hoped for, the flame went out too quickly to take a good picture.

The oxidant and the fuel
A porridge of oxidant and fuel, calcium nitrate Ca(NO3)2 and potassium ferrocyanide K4[Fe(CN)6]
The very end of the rocket fuel flame burning
chemistry, Experiments, Together with sis

A booming start of the year

We used electrolysis (with sodium hydroxide NaOH solution as the basic medium) to produce oxyhydrogen and extinguished the candle by means of the reaction between hydrogen and oxygen. 

When electrolyzed, water decomposes into two gases: oxygen O2 and hydrogen H2. The end result is twice as much hydrogen as oxygen. Such a mixture of gases is called oxyhydrogen. When a bottle full of oxyhydrogen is placed near a burning candle, the gas ignites immediately and blows out the candle.

Simon also performed two more experiments to purify water (from heavy metals using resin and organic pollutants using activated coal).







chemistry, Crafty, Experiments, Group, Museum Time, Notes on everyday life, Physics, Together with sis

Science Day in Belgium

Yesterday we attended one of the hundreds of Science Days venues open for free all over Belgium. Simon particularly enjoyed chemistry demos, even though he was disappointed that some companies showing their inventions didn’t want to share the actual formulas behind the tricks.

The simple non-newtonian fluid remains a favourite.

Making your own bath bombs.

Simon dazzled by how insulator foam (polyurethane) is produced as the result of a reaction between two highly viscous substances, an isocyanate and a polyol (polyether). Another fascinating thing about this demo was that the tool mixing the two ingredients actually employed magnets!

A workshop explaining why ships don’t sink and if they do, why:

Exploring 3D printing:

Programmable spheres:

Heat indicator (material changing color depending on water temperature):

The good old baking soda and vinegar demo revisited:

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Molecules

Simon is seriously enjoying his new Molymod chemistry modeling sets and has been obsessing about which set contains what atoms and bonds.

Alcohol (Ethanol):

Hurray! We have just built 7,333333333333 x 10^-9 of the human DNA:

Glucose

Some like the football, Simon plays with the buckyball, or Buckminsterfullerine, made up of 60 carbon atoms:

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Sugar and Salt

Want some me sugar in your tea?

Simon built this sucrose (table sugar) molecule with the help of Theodore Gray’s Molecules book (although he is pretty sure there is a mistake in the Dutch version of the book, on a different page, where the fructose, glucose and galactose molecular structures seem to be mixed up – the sucrose description helped him discover this as the table sugar molecule is made up of one fructose and one glucose molecule).

Simon is also fascinated how sugar and salt, substances that are easy to confuse on the kitchen table, are made of molecules that are so “wildly different”:

chemistry, Crafty, Experiments, Physics, Together with sis

Physics Experiments: Capillary Bowl

Simon really wanted to try building a capillary bowl – a version of a perpetual motion machine in which water circulates. Although aware of the fact that perpetual motion was not possible, he is keen on seeing it for himself. Off we were to the hardware store where we got some funnels and hoses. What we observed was Pascal’s law in action: the level of water evened out and there was no way to get the water rise higher at one end of the hose than at the other and thus no way to get the water flow into the funnel.

Eventually, we did manage to get the capillary bowl to work for a split second when we filled it with coke and beer. The pressure of water is higher than that of foam, because liquid has a higher density than foam. We used alcohol free beer, so there wasn’t that much foam.