Wednesday, 4 June 2014

The graphs and tables of 3A


Done by us:






Done by professor:

Introduction of fastest dive challenge and theory behind it.(3A)

There were three parts 1)Choose one of the sphere of different size which will touch the bottom first.-                light object and heavy object.
                                    2)Choose one of the shapes which will  touch the bottom first.

1)There were three different sizes.

We chose the middle-sized ball but in the end the largest ball was the fastest.
Through the process,we used the formula '(mg-u)-kv=ma'.
(mg-u) is always constant ,v refers to volume,m refers to mass and a refers to acceleration.


2)There were different shapes
we chose the shape that looked like a tablet or diamond but in the end the sphere was the fastest.
This is because along the way,the figures changed its direction.Since the sphere has a fixed shape,it was less affected by the resistance.

Introduction of fastest ball challenge and theory behind it.(3A)

There were 3 experiments in this topic-the fastest ball challenge/achieving 1.2s/achieving 1.4s.

<The fastest ball challenge>:
The main idea of this challenge was to try various angles and distance to find/achieve the fastest time for an iron ball to travel between the two photo gates.
We had to use the concepts of conservation energy,kinetic energy and potential energy.

-Energy is neither created or destroyed.
-The energy can only be transformed from one state to another.
-formula for gravitational potential energy:mgh
-formula for kinetic energy:1/2mv^

The most suitable angle:35.2º
Our angle:36º

Tuesday, 3 June 2014

Images with description(sorry but not so clear)-3B version 1

These are the 8 teabags with tea leaves.

This is the calcium carbonate powder
This is the mixture that we get after stirring the calcium carbonate powder and the tea leaves.
This is the 'Buchner filtration'

This apparatus was used to give pressure in the flask.
After that we had to put our solution into the cold water basin to cool it.
There are two layers in the separating funnel.This is due to difference in density.
The magnesium sulphate powder clumped in the presence of water.

It's very unclear as the filter paper and the crystals from magnesium sulphate powder are white in colour...
Green caffeine solid

Basic techniques that we learnt in this experiment -3B

1.
At first we were given 8 teabags and tea leaves.
In the tea leaves,there are 3 chemicals.They are cellulose,caffeine and tannins.
(The cellulose is not soluble and tannins are bitter in taste.)
Our challenge was to extract caffeine from the mixture consisted of caffeine and tannins.
So in order to achieve this,we had to put calcium carbonate powder to keep the tannin joining the caffeine.

2.
When we extracted caffeine  by distilling off the dichloromethane on a rotary evaporator,we had to use hot water.This is because as the temperature increases,the effects will also increase.

3.
During the 'Buchner' filtration,we had to use 2 filter papers to purify the suspension.Then we had to apply pressure by turning the 'pressure button' in anti-cockwise way.
After that,the bubbles could be seen in the purified filtrate.

4.
Next we had to put the flask inside the basin of cold water in order to cool the filtrate down to the room temperature.

5.
When we used separating funnel,we could see two layers.The top layer was aqueous layer and the bottom layer was organic layer. The different density caused different layers.The organic layer was at the bottom because it had a higher density.

6.
Although we had gone through filtration,the organic layers were not pure.So we had to add magnesium sulphate powder.The magnesium sulphate powder clumps in the presence of water.

7.
During the process of extraction,the flask was cold  due to the evaporation of dichloromethane.

Brief introduction about caffeine-3B

What is Caffeine?
-It can be found in tea,coffee and nuts.
-It is an alkaloid.
-It is a compound.
-Positive effects on human body:Reduce drowsiness and improve alertness
-Negative effects:Addiction,headache and hallucinations.

This clearly shows that some alkaloids are beneficial and others are very harmful.