Lesson 7

For this lab lesson, my partners were Joyce, Chin Ying and Min Yi. The pictures say it all!

 Experimenting, experimenting...

 And more experimenting!

 One of the many set-ups we used, and some of our raw data.

Creating our very own 'crime scene' in the toilets, then cleaning up the mess afterwards! 

On the left is our group's work, which has an extremely structured storyline.

 Some of the other groups' (art)work.

Whee! Our final product. I shall refrain from putting up the whole sequence of how the murder was committed, since another group has to solve it first! 

The pink bits are supposed to be the words 'Majulah Singapura', for your information.

My group has also plotted our data into graphs to observe the trends and relationships, as below.

The whole class's graphs are on a single spreadsheet, at the following link:                     https://spreadsheets.google.com/spreadsheet/ccc?key=0AmiXOZN9ezMsdEMyRjYtbFJLM0pJQ3VBb1hiNmViZVE&hl=en_US#gid=0

Lesson 5 and 6

Lesson 5 was a briefing on the CSI PT (group), along with a video (edited from a Japanese movie) showing a CSI case. I missed quite a bit of this lesson, only managing to catch the end of the video, due to a lengthy MSP phototaking. :(

In lesson 6, we were introduced to the idea of blood spatters! Using the shape and size of blood spatters, we can actually know more about the crime committed, for example, what kind of weapon was used and how the victim might have been injured/murdered. Another video was shown to better illustrate the workings of analysing blood splatters, and how it can be quite misleading at times.

A lesson learnt from this video is: do not jump to conclusions! Make unbiased observations first before inferrences. Keep an open mind at all times. I think this is really important for scientists and in this case, the CSI people, because the answers to a case might not be as expected.

Next up in lesson 7 would be hands-on experiments on blood splatters, investigating how the distance between the blood drop and the surface, as well as the latter's angle of elevation, affects the shape and size of blood splatters.

Chromatography Rf Values

First digit '9'

Solvent front: 12.3 cm
Blue: 11.1 cm
Pink: 9.9 cm

Rf Values
Blue: 0.902
Pink: 0.805

Second digit '0'

Solvent front: 11.7 cm
Blue: 9.1 cm
Pink: 8.3 cm

Rf Values
Blue: 0.778
Pink: 0.709

Third digit '0'

Solvent front: 11.5 cm
Blue: 9.1 cm
Pink: 7.4 cm

Rf Values
Blue: 0.791
Pink: 0.643

Fourth digit '0'

Solvent front: 11.1 cm
Blue: 7.0 cm
Pink: 4.2 cm

Rf Values
Blue: 0.631
Pink: 0.378

Fifth digit '0' (the weird one)

Solvent: 12.1 cm
Blue: 7.1 cm
Pink: 5.9 cm

Rf Values
Blue: 0.587
Pink: 0.488

Lesson 3 and 4

Lesson 3 was spent on reading up on rambio about the various colours emmitted when ceratin metals are heated over the flame. This technique is known as flame test.

Today (lesson 4), we carried out a chromatography experiment, as well as a very fun hands-on flame test! First, we had to identify forgery in a cheque using chromatography. The first step was to cut up the written numbers, and then soak them in (a bit of) ethanol. Next, a few drops of the different ink solutions were dripped onto separate chromatography strips, which were then dipped in water. Pictures below to illustrate the experiment. 

Cutting up the cheque

Ethanol used

Soaking the paper with ink in ethanol

The chromatography set-up

Chromatography strips at end of experiment

Second is the flame test! Below are the really cool pictures of the flames when the different metals were held over them. 

Potassium nitrate

Barium nitrate

Calcium chloride

Sodium nitrate

Copper (II) nitrate

Magnesium

Lead (II) nitrate