Thames & Kosmos Color-Changing Crystals handleiding

Niet gecategoriseerd

Thames & Kosmos

2 pagina's

PDF beschikbaar

Handleiding

EXPERIMENT 1

EXPERIMENT 2

EXPERIMENT 3

Check it out

WHAT’S HAPPENING? The granules of salt crystal will dissolve in warm

water and eventually turn invisible, since you can’t see their smallest components —

called ions — with the naked eye. When the water cools, the ions gather into a very

specific shape, which eventually turns visible again — a crystal has taken form!

YOU WILL NEED:

› Safety glasses, potassium alum, lid

remover, potassium hexacyanofer-

rate(III), measuring cup, wooden

spatula, water, old cooking pot, triv-

et, pot holder, clean, empty jelly jar

(without lid), paper towels

››› First, put on your safety glasses and

get a trivet or hot pad ready for your

work area.

››› Use the lid remover to open the

chemical vial with the potassium alum

(potassium aluminium sulfate), and

empty the entire contents into the jelly

jar.

››› Using the wooden spatula, add 3 to 4

scoops of the potassium hexacyanofer-

rate(III). You can use all of it except for

a little bit, which you will need later

for the chemical analysis.

YOU WILL NEED:

› 2 display cases, scissors, tape, small

screwdriver

›››

Divide the crystals between the two

display cases. Cut the yellow and blue

labels out of this instruction manual

and clamp them in place between the

lid and the bottom of the two cases. If

they don’t stay in place, secure them

with a little tape.

Which crystals change the most quickly? Do the

crystals kept in the dark change color too?

Growing color-changing crystals

“Magical” transformation

Caution!

Make sure that nobody,

particularly any young children, can get into

the crystal display cases!

Tip!

You can lock the

case by squeezing it

tightly shut. To open it,

insert a small screw-

driver into the slot

on the side and

turn it carefully.

Tip!

You will want to be absolutely sure

that the salts are completely dissolved

— that way, you will have the best chance

of growing nice crystals.

Tip!

This is the right way to use the pipette:

Squeeze the upper part of the pipette between

thumb and forefinger, and dip the tip of the

pipette into the liquid. As soon as you release

pressure on the bulb, the liquid will rise up the

pipette tube. By applying careful pressure to

the bulb again, you can either empty the pipette

contents completely or squeeze out just

a few drops.

Before filling the pipette with the next

chemical, you will have to clean it carefully. To

do that, draw some clean water into the

pipette, shake, and squeeze it empty. Repeat

this procedure several times.

››› Use the measuring cup to measure 50 ml of

water (1 x 20 ml and 1 x 30 ml) and add the

water to the two chemicals in the jar. Stir

everything well with the spatula.

››› Fill the pot about 2 cm deep with water.

Bring the water to a boil on the stove. Then

turn off the stove and set the pot carefully on

the trivet or hot pad.

››› Now place the jelly jar holding your chemi-

cal mixture in the pot and stir it with the

wooden spatula. The hot water will warm

the contents of the jar, and the two salts will

gradually dissolve. If you can still see some

alum granules, remove the jar from the pot

with a pot holder. Bring the water in the pot

to a boil again and repeat the process.

››› Label the jar and set it in a safe place. Now

you just have to wait! But after a few hours,

you will find transparent angular shapes on

the bottom of the jar, which will keep form-

ing with time. After about two days, your

crystals will be “all grown up.”

Chemical analysis

YOU WILL NEED:

› Safety glasses, remaining potassium

hexacyanoferrate(III), 2 measuring

cups, pipette, household white vinegar,

iron nail, water

››› Pour some household white vinegar into

the measuring cup. Place the nail in it

and set the cup in a safe place for a few

days. The vinegar will gradually dis-

solve some of the iron, which will show

itself as a brown coloration.

››› Add the rest of the potassium

hexacyanoferrate(III) to the other mea-

suring cup and dissolve it in a little

water.

››› With the pipette, carefully drip a little

potassium hexacyanoferrate(III) solu-

tion into the measuring cup containing

the vinegar.

WHAT’S HAPPENING

There’s a chemical reaction that

takes place in the crystals, as

you will learn in greater detail

in Experiment 3. Because the

reaction happens more quickly

under the influence of light,

the crystals change their color

faster in a bright location than

in a dark location.

WHAT’S HAPPENING

Right away, you will get a greenish to blue color.

You just performed what’s called a chemical

analysis. You used one substance (the potassium

hexacyanoferrate) to test for the presence of

another substance (the dissolved iron from the

nail). In other words, the two substances reacted

with each other chemically and formed a vivid

blue dye that serves as a clear indication that the

reaction took place. This dye is known as Prus-

sian blue.

This same reaction took place in your crystals.

Potassium hexacyanoferrate(III) contains iron as

well, although it is so “hidden” inside the crystal

that at first no Prussian blue formed. Only with

the help of the alum, which gradually decom-

poses the red salt, does the color appear in the

crystals, and the yellow slowly turns to green

and then blue.

Caution!

Have an adult help you! Be very

careful not to burn yourself on the hot pot,

and don’t forget to turn off the stove!

›››

Ideally, place one of the display cases in a

dark closet and the other one on a bright

window ledge. Compare the colors of the

crystals every three days or so.

CULPRIT NABBED… THANKS TO CHEMICAL

ANALYSIS!

When the police get to the scene of a crime, they search for clues.

These days, though, it isn’t just fingerprints that might lead them

to the perpetrator. Chemical analysis of DNA helps them in their in-

vestigation too.

DNA is a complex chemical compound that is found in

every cell of your body. It can act as a sort of “biological fingerprint”

— because no two people have the same DNA. This compound con

tains all the biological information of an individual, such as height,

sex, eye color, and hair color.

But let’s get back to the crime

scene. The police will look for

cells from the perpetrator’s body,

which may be contained in the

roots of a hair or small flakes of

skin, for example. The DNA in

these cells is analyzed and com

pared with DNA from the cells of

any suspects. This technique has

already been used to solve a lot of

crimes!

WHAT IS PRUSSIAN BLUE USED FOR?

This blue dye has been popular for centuries, because it has an in

tense color and doesn’t fade. If you have a set of paints, you might

also find this color under the name “Berlin blue.” Even today, it is

processed into paint dyes and used for the blue color in ink

cartridges.

Prussian blue, or Berlin blue, was discovered in 1706 by a paint

manufacturer in Berlin, in a region of Germany that used to be

known as Prussia — hence the name!

cell

nucleus

Cells form the smallest

building blocks of humans,

animals, and plants. Our

skin, our bones, and our

muscles, for example, are

made up of countless cells.

They are so tiny that they

are only visible under the

microscope. The DNA is

contained inside the cell

nucleus, which is con-

tained inside the cell.

CYANOTYPE

The chemical reaction from Experiment 3

also forms the basis for an unusual photo

graphic process known as cyanotype. In

this process, thick paper is painted with a

solution of red potassium hexacyanofer-

rate(III) and a special iron-containing salt

that gradually decomposes in the light and

then reacts with the red potassium

hexacyanoferrate(III).

If this kind of paper is covered with a sten

cil, for example, and allowed to sit in the

sunlight for a little while, only the parts ex

posed to the light will turn blue.

This process was used by the British bota

nist and illustrator Anna Atkins, who had a

book displaying pictures of various plants

that were created by the cyanotype

technique.

››› Use the wooden spatula to carefully re-

move the crystals and place them on a

paper towel to dry. Depending on how

warm or cool it was when the crystals

were growing, they will have turned

yellow or yellowish green. Pour the left-

over solution down the drain with lots

of water, and rinse thoroughly.

Bright Crystals Dark Crystals

Bekijk gratis de handleiding van Thames & Kosmos Color-Changing Crystals, stel vragen en lees de antwoorden op veelvoorkomende problemen, of gebruik onze assistent om sneller informatie in de handleiding te vinden of uitleg te krijgen over specifieke functies.