CuSO4 Crystals, Yum

Crystal Revision

These are COPPER SULPHATE CRYSTALS (CuSO4)

Method:

Part 1:

1. Weigh 7g of copper sulphate powder into a 250ml beaker using an electric balance
2. Collect 100ml of copper sulphate into a second beaker
3. Add 7g of copper sulphate to the solution and stir (to make solution saturated)
4. Heat beaker and stir to dissolve the solid powder (solution now supersaturated)
5. Pour the warm solution into the clean petri dish until 2/3 full and leave overnight (time is required in order for the solution to cool and solidify into crystals. The solution is now less but still supersaturated)
6. Cover the rest of a solution with a cardboard lid

Part 2:

7. Choose 2 seed crystals and place them on clean paper. (Shape/figure is more important than size as it is the template for the final crystal) Measure and draw one crystal. DO NOT TOUCH THE CRYSTAL (copper sulphate is poisonous and thus potentially harmful)
8. Tie a slip knot around the other seed crystal with cotton thread
9. Suspend the thread through the cardboard lid
10. Tip the remaining crystals back into the solution. You may need to scrape the crystals with a spatula (Crystals may have solidified onto the bottom of the dish)
11. Heat the solution until ALL of the solid has dissolved (This is increasing the saturation of the solution again)
12. COOL the solution in a shallow, cold water bath (otherwise the suspended seed crystal will melt)
13. Hang the crystal in the cool solution and leave to grow

Explanation:

As the supersaturated solution cools, the excess copper sulphate will solidify onto the seed crystal. Shape is maintained though the size will increase. Particles basically join evenly to the template as opposed to falling to the bottom of the beaker.
-Crystals grow by adding single layers of molecules at a time
-As the water cools and evaporates, the solid is forced out make these layers
-Crystal shape depends on the arrangement of atoms

Definitions:

Solution: Mixture of substance dissolved into another, solvent + solute = solution

Solvent: Does the dissolving (usually liquid, H2O)

Solute: Is dissolved (CuSO4 powder)

Unsaturated solution: Where the solution can hold more than what is dissolved into it

Saturated solution: Where the solution is holding exactly what it can. Adding excess will result in solid falling to the bottom, but solution itself remains saturated.

Supersaturated solution: Where excess solute is dissolved into the solution. It requires heat. When cooled, particles will be forced out of liquid and re-solidify.

Geog Revision

Plate Tectonics Revision

Wegener’s continental drift theory stages:
200 million years ago - Supercontinent Pangaea, Australia touching Antarctica and Indian Asia
180 million years ago - Split into Laurasia up north and Gondwanaland south
135 million years ago - Continents began to break up, Australia attached to Antarctica
65 million years ago - Further breaking up, Australia moved north-east into isolation
Today - Current positions
50 million years later – Australia to move further north
Types of plates:

Continental Plates:
 Carry land masses, continents, above
 Some also hold oceans, but they are named after the land. Eg. North American Plate
 Made of lighter, less dense rock. Eg. Quartz and feldspar
 Normally do not subduct
Oceanic Plates:
 Carry oceans above
 May carry small land masses, islands, but named after the ocean. Eg. Pacific Plate
 Made of heavier, denser rock. Eg. Mainly basalt, (granite?)
 Tend to subduct in a collision

Important information:
-Rocks deep underground can be studied through rocks from volcanoes and by looking at seismographs or seismic waves (shifting rocks create energy)
-Deep underground, the high pressure keeps rocks solid by compacting and compacting particles (liquid takes up more space than solid)
-Middle of earth probably made of iron, as rock alone would not be able to make up the weight (measured using Cavendish balance) and magnetism of the earth which make compasses work is based on this iron core. The field of magnetism from N to S poles protect the earth from solar winds
-The middle of the earth is liquid outside and solid inner section
-Like gases, hot molten rock will rise (to form volcanoes) and cool rock will sink
-Volcanoes are created when molten rock rises through up through the crust
-When a plume of hot rock pushes through the mantle, cooler rock is forced aside causing volcanic ridges. The old crust moves aside and magma fills the gap to develop new crust
-Positions on the edge of a plate are more tectonically active. Australia is in centre so it is not
-A normal fault is where rocks are pulled apart and one side drops down
-Large faults can cause earthquakes
-Folding and breaking of rocks plus grinding of one plate under another can cause earthquakes to occur
-When rocks break and slip, earthquakes can occur
-Trench is a long narrow valley on the ocean floor
-Subduction is the action of a plate (usually oceanic) sliding beneath another plate upon collision
-When an oceanic plate subducts and causes an earthquake, a tsunami can also occur
-Subduction zone is the area where a plate subducts
-Plates are constantly on the move, they move at a rate of 5 to 15cm per year

Convection Currents:
This is the heat-driven motion that causes plates to move and rocks to travel in a circular motion within the earth. They are within the mantle
Currents moving away from each other = diverging = crust pulled apart
Currents moving toward each other = converging = crush pushed together

Plate Boundaries:

1. Divergent/Constructive Boundary
-Movement of plates away from each other
-Plates can be oceanic or continental
-Gap caused called a rift or ridge
-Magma fills rift, volcano formed
-New crust created
-e.g. Mt Kilimanjaro, East African Rift, Mid-Atlantic Rift, Iceland

2. Convergent/Collision/Destructive Boundary

-Plates move toward each other
-Ocean to continent = oceanic crust subducts and melts, land on continental crust folds upward, volcano and rift forms. E.g. Mt St Helens, USA

-Ocean to ocean = one piece of crust subducts and melts, volcano (underwater) and trench forms. E.g. Japan, Indonesia, Caribbean Islands, Philippines (island arcs)

-Continent to continent = none or very little subduction occurs; continents on top of the plates collide and fold upwards to form mountains. E.g. Himalayas (Indian and Eurasian Plates), Andes (fold mountains?)

3. Transform/Conservative Boundary
-Plates slide alongside each other
-Can be oceanic or continental
-May move in the same or opposite direction
-Causes a fault e.g. Sand Andrea Fault, California (Pacific and North American Plates)

Helpful sites:
http://geology.com/nsta/convergent-plate-boundaries.shtml
http://www.waterencyclopedia.com/Oc-Po/Plate-Tectonics.html

Maths Tests

Hello everybody!

Unless you were sick, away, at strings, or extremely lucky, you have probably had a maths test today. It was on linear graphs; a topic which appeared to be of a quarter science, a quarter finance, a quarter maths and the rest was dot-to-dot. I’m not sure about you, but I didn’t go too well. At any rate, it has inspired this post on:

MATHS TESTS

Okay, firstly here’s a joke:
Q: How many legs does an octopus have?
A: Eight
This one was courtesy of year 5 maths. It does make you wonder, who makes these maths worksheets?

But back to the point, maths tests can be exceedingly stressful experiences, but with the right steps, they could become mildly acceptable. Enjoyable even. And then again, maybe not…

Firstly though, it’s very important to realise that although maths tests can’t technically be studied for and certainly can’t be crammed for, it is possible to study for maths. It’s very much like what the language teachers say, “a little every day”. If you do, maybe one or two questions every single day, you’ll eventually find that you can do them much more efficiently and easily.

Another integral aspect of maths tests are the point allocation. You need to know what your strengths are:

1. You’re better at the skills section. In this case, by all means work the test out in order. It gives you time to perfect the skills and thus get a better mark. However, despite having less time for skills, doing analysis first would give you more opportunity to do well on this section, especially since it is usually worth more marks.

2. You’re more analysis oriented. Here, it would be ideal to do the analysis section first. It is often worth more marks, and you will have a more relaxing end to the test.

Contrary to belief, people often think analysis is harder. Teachers think that we think it’s harder too, meaning they often make numbers more convenient. The important thing with analysis is:
1. Show working out, if not for the teacher at least for yourself
2. Check everything carefully
3. If the answer is an unusual fraction, check it even more carefully
4. Draw diagrams
5. Label and USE the diagrams

Personally, I often find that skills can sometime be more difficult. They use weird numbers resulting in strange answers, so it’s difficult to tell whether you are correct or not without re-doing the whole question. Also, generally working out will not earn you any points, so careless errors are very easy to make.
Finally, I will sum this up with my top tips for maths tests:
1. Check if your teacher prefers pen or pencil
2. Show all working
3. If there is a sentence question, use a sentence answer
4. Draw and use diagrams where appropriate
5. Check everything
6. Read all questions before starting, it often calms me down
7. Revise by doing a little very often
8. Watch the time
9. If you are struggling, move on and answer it later, but don’t leave any blanks
10. My personal top tip from today’s experience: Don’t stab yourself with lead pacers where the lead may get stuck in your finger. It not only creates frightening stains on your test, but it also wastes between 10-20mins of time.

Anyway, happy testing! Or not…

ihearthorses