20 мин
10 октября 2019 г.

Chemistry lab for children Analyses

Chemistry lab for children. Analyses.
Автор: Laba.Media

Chemical elements are everywhere. They are the bricks of the Universe. They are both in our body and distant stars. Check your knowledge, would you be able to distinguish solid facts about chemical elements from made-up skimble-skamble?


Please enter “true” or “false”

1. Dry ice consists of water

False, dry ice is frozen carbon dioxide (CO2), there is no water there.


2. A car can run on carbonated water with added syrup

True, this happens due to jet force. By the way, Nikolay Nosov described this phenomenon in “Dunno”.

Cola-powered car: https://youtu.be/SNu1gnit6sE


3. Obsidian is molten lava.

True! Obsidian is a type of igneous rock, a volcanic glass formed upon rapid cooling of molten rock (also knowns as lava). The principal minerals in obsidian are quartz and feldspar. You can find obsidian all over the place -- in Minecraft, for example!


Choose one correct answer

4. Why is this Pushkin statue green (even though it’s made of bronze)? //See the statue in the picture enclosed.

A. bird droppings

B. the surface of bronze is oxidized by air

C. when outside, bronze gets covered by mold

D.  statues are covered with protective paint

When attacked by carbon dioxide and water vapours, a layer of basic copper carbonate is formed under the surface of bronze statues -- and it’s green.


5. Choose the type of paint that’s insoluble in water:

A. Gouache

B. Watercolour

C. Egg tempera

D. Oil

Gouache and watercolour are quite soluble in water, egg tempera is water-based (which means that even when it contains an emulsion that’s insoluble in water, it can still be removed with water). Oil, on the other hand, does not mix with water at all due to its chemical nature. Scientists call oil-based paint “hydrophobic”.


6. What happens when you put a drop of iodine solution on a peeled potato?

A. It turns blue

B. It turns yellow

C. It turns black

D. A hole appears

A blue spot formed upon the reaction with iodine is a test for the presence of starch.


7. We just shattered a mercury-containing thermometer. What’s the best and safest way to collect all the spilled mercury?

A. Use sticky tape 

B. Cover it with table salt

C. Use a vacuum cleaner

D. Open the window and air out the room

It is not a good idea to leave metallic mercury lying around since it can evaporate (its vapours are quite toxic). Airing out the room is fine and all, but only after taking certain measures to remove mercury from all the surfaces. Vacuuming is a no-no: mercury can get stuck in the vacuum cleaner and the larger globules can get broken up. (The Russian EMERCOM recommends burying or outright destroying the vacuum cleaner afterwards). Table salt wouldn't help either (it doesn't react with mercury). The correct algorithm is this: first, put on gloves, optionally you can put on a surgical mask as well. Ideally, you should be wearing clothes and shoes that you'd be fine getting rid of afterwards. You should collect mercury with duct tape (alternatively, you can use a syringe, an enema, a plaster, or modeling clay). Larger drops can be picked up with a piece of paper. The collected mercury should be put in a container together with a concentrated solution of potassium permanganate (when unavailable, a jar of cold -- and only cold! -- water will do). Then you should wipe the site of your spill with the permanganate solution.

Please refer to the EMERCOM website: http://www.mchs.gov.ru/dop/info/smi/news/Novosti_glavnih_upravlenij/item/457978.

Everything that was in contact with mercury should be handed over to the authorities (NOT thrown away). Carefully rinse your mouth, brush your teeth and take a few tablets of activated charcoal. Check whether you have any mercury poisoning symptoms.


Attention! If the mercury from the thermometer got spilled on textile or if the spill occurred in a place where it’s impossible to collect the mercury (a room with gaps in the floor or a room with many things on the floor), you cannot proceed without the help of specialists. It is vital to do the following: 1) lead people and animals away from the room; 2) open a window while avoiding drafts; 3) contact the specialists from a laboratory in your local Health Department or in EMERCOM. You can listen to instructions after calling 112 (emergency number).


8. When alcohol is mixed with water...

A. Volume and temperature decrease

B. Volume increases, temperature decreases

C. Volume and temperature increase

D. Volume decreases, temperature increases

Only the last option is correct. Upon mixing alcohol and water, the volume decreases while the whole mixture gets hotter.


9. How much sugar (at most) can dissolve in a glass of boiling water (200 ml)?

A. 2-3 teaspoons

B. Half a glass(50 g)

C. 100 g

D. 1 kilo 

Sugar is quite unusual in that high volumes of it can dissolve in significantly lower volumes of water. In this table, solubility of sugar in water is listed for different temperatures:

According to this table sourced from English-language Wikipedia, even at 90°C 420 g of sugar can be dissolved in 100 g of water, which means that you can dissolve almost a kilo of it in 200 g of boiling water.


10. When making fireworks, salts of different metals are added to gunpowder: sodium, lithium, copper, barium. Adding this element makes the firework blue:

A. Aluminium

B. Magnesium

C. Sodium

D. Copper

It is widely accepted that both fireworks and gunpowder itself were invented in China. The Chinese were also the first to make colored fireworks. The technology barely changed since.

for green colour - barium salts;

for red colour - strontium salts;

for blue colour - copper salts;

for orange colour - calcium salts;

for yellow colour - sodium salts, etc.

Bright colored lights appear due to bands in absorption and emission spectra.


11. Inhaling this gas makes your voice high-pitched and cartoonish:

A. Nitrous oxide

B. Helium

C. Argon

D. Xenon

Nitrous oxide, also known as “laughing gas”, does not affect the pitch of your voice. Argon is very inert, it also does not affect the pitch of your voice. Helium, on the other hand, affects vocal cords upon inhaling (it is due to helium being very light). Higher pitch makes you sound like a cartoon character. A reverse effect can be observed upon inhaling xenon (the gas is heavy so it makes the pitch of your voice low -- while also inducing medical sleep).


12. How can you descale a kettle?

A. Lemon juice

B. Baking soda

C. Strong tea

D. Table salt

Usually, scale consists of deposed calcium and magnesium carbonates. The thing is, tap water is usually “hard” (meaning that it contains calcium and magnesium salts), reacting upon boiling and depositing those carbonates inside the kettle. Acids (including citric and acetic acids) dissolve carbonates, releasing carbon dioxide. By our observations, to descale a kettle, the amount of juice that comes from half a lemon is quite enough (that means you should pour water into a kettle, squeeze half a lemon into it and turn on the kettle).


13. What isn’t included in the recipe for black powder, originally invented in China?

A. Sulfur

B. Coal

C. Saltpeter (potassium nitrate)

D. Magnesium shavings

When heated, saltpeter releases oxygen, oxygen ignites coal and sulfur, releasing large amounts of gases. Without any doubt, magnesium shavings burn very brightly in air too; however, they are not used to make gunpowder.


14. Blood can be so different! Red and green and all of that! But what colour can’t blood be?

A. Red

B. Green

C. Blue

D. Colourless


15. This element of the Periodic table does not exist in the form of minerals. However, its chemistry has been widely studied and is fairly well-explored, since the military can’t get enough of it. This element is:

A. Americium

B. Plutonium

C. Uranium

D. Dubnium

The element plutonium is almost non-existent in nature since it’s radioactive (consequently, it decays). The Earth’s crust has such minuscule amounts of it that its mining is not viable. Nevertheless, it’s widely used to make nuclear weapons and atomic reactors and that is why it is produced in industrial quantities with uranium and other elements as initial reactants.