Sugar Crystal Growth

For our holiday homework, we had to grow sugar crystals! :)

Sugar crystals are grown based on the concept that solubility of a liquid decreases when its temperature decreases.

Materials:
1 pot
1 measuring cup
1 cup of water
3 cups of table sugar
2 glasses (I prefer glasses because it is transparent and you can look through to see how the crystals are growing)
*Note: always have >1 setup in case one fails-that's why I use 2 glasses
2 pencils/knifes
Two pieces of string (should be able to be tied around the pencil/knife and lowered into glass almost but not quite touching bottom of jar-about 1-2cm leeway)
One tray filled with tray (used as a moat to keep ants and other insects from disturbing your setup)


Step 1: Boil a pot of one cup of water.
Step 2: When it has finished boiling, pour in all 3 cups of sugar.
Step 3: Put the 2 glasses on the tray. (Ensure the tray is placed in a place with minimum dust and chance of disturbance)
Step 4: Pour it into the 2 glasses (*BEWARE IT'S HOT)
Step 5: Tie the string to the pencil and slowly lower it in. Ensure string is not touching any part of the glass.
Step 6: Wait. After a week or so, your crystal should grow!

Reference: http://www.kidzworld.com/article/26598-make-your-own-crystals



When the water is boiled, its solubility increases. Hence all the sugar can dissolve in it. However when it cools down its solubility decreases allowing less sugar to dissolve. Hence the sugar that can no longer dissolve crystallises on the string and voila, you have a sugar crystal.

After a week, my crystals are growing both on the string and on the surface of the water :O
But why?

After finding out from my friends, it is better to put a small piece of rock sugar on your string first. The sugar in the water will then gather around that piece of rock sugar. Else there is a high chance it won't grow on your string. That is something I need to take note of in the future.

(I'm not too sure whether that is allowed though)

Try this out at home! You can eat it after it's finished, or even add food colouring to decorate it!

That's all for now!

Term 2 Week 3

This week we learnt about the states of matter with regards to heat as well as how to explain their conversions with kinetic particle theory. We also learnt how to interpret graphs regarding heat gain or loss over time.


Internal energy is the combination of the total kinetic and potential energy of particles in a body.
Kinetic energy is due to the vibration and translation of particles. Temperature is a measure of the amount of kinetic energy for a certain amount of an object or body.
Potential energy is stored like a spring-the attractive forces between particles are stretched and compressed accordingly.

Kinetic particle theory explanations-model answers:

In explaining a change in state with kinetic particle theory there are 4 sections:

• describe the amount of a type of energy lost
• movement and arrangement of particles
• threshold as to the forces between the individual particles
• description of final state

Melting

•When a solid is heated, the particles absorb heat energy

•The particles gain kinetic energy

•Start to vibrate faster

•And move further apart

•At melting point, enough potential energy to overcome the strong forces of attraction

•The particles start to break away from one another

•solid becomes a liquid

•At the liquid state, the particles start to roll and slide over one another

Freezing

•When a liquid is cooled, the particles lose heat energy

•The particles lose kinetic energy

•slide and roll less vigorously

•At freezing point, particles have not enough potential energy  to overcome the strong forces of attraction holding them together.

•particles start to come together in a regular arrangement and the liquid becomes a solid.

Boiling

•When a liquid is heated, the particles absorb heat energy

•The particles gain kinetic energy

•Slide over each other more rapidly

•the particles gain sufficient potential energy to overcome the attractive forces between the particles

•And move far apart rapidly in all directions

•Forming a gas

Term 2 Week 4

This week we learnt about the elements of the periodic table.

Firstly, what are elements? Element comes from the latin word elementum which means principle, rudimentary. Element thus implies something basic. In chemistry, any substance than cannot be broken down into further simpler things is an element.

Some element components of substances:

Water: Hydrogen, oxygen
Ammonia: Nitrogen, hydrogen
Fructose: Carbon, hydrogen, oxygen
Deoxyribosenucleic Acid: Carbon, nitrogen, oxygen, phosphorus
Polyvinyl Chloride (PVC): Carbon, hydrogen, chloride
Fat: Hydrogen, carbon, oxygen
Paracetamol (Panadol): Carbon, hydrogen, nitric oxide (a compound of nitrogen and oxygen)
Chlorophyll: Carbon, hydrogen, oxygen, nitrogen, magnesium
Protein: Carbon, hydrogen, oxygen, nitrogen, R group elements (polypetide amino acids)

In the human body, there are usually:
Oxygen from air and water
Carbon from carbohydrates and as a byproduct of cellular respiration
Nitrogen from the air, cured meats and plants
Calcium from milk, fish, vegetables
Phosphorus from food like red meat and poultry, dried milk, dairy products, bran, seeds
Iron from red meat
Magnesium from vegetable and whole grains
Potassium from leafy vegetables and beans
Zinc from seafood

Different elements were found at different times. (13 in the antiquity to middle ages, 21 in the middle ages etc)

Some of the elements took longer to discover as they either too unstable to be isolated as a single element, had limited uses at the time, or were rare (e.g. francium).

Metals are elements with metallic properties, properties such as:
Good electrical conductivity (for solids)
Shiny
Strong
Hard
Malleable (can be bent)
Ductile (can be streched)
Good heat conductivity

All the elements on the periodic table are metals except:

Hydrogen, carbon, nitrogen, oxygen, fluorine, neon, phosphorus, sulfur, chlorine, argon, selenium, bromine. krypton, iodine, xenon, radon

*GENERAL NOTE: SOME OF THESE POSTS MAY NOT BE CONCLUSIVE AS THE REST IS CONTINUED ON THE NEXT WEEK