Food Additives : Good or Bad?

The video clip was produced by Nurul Fazleen & Hanis Suraya from 5 Bakerara for Blog for Chemistry Challenge 2013 during Science and Mathematics Week.

Determining Empirical Formula of Magnesium Oxide

Questions to ponder:

1. What's the purpose of cleaning magnesium ribbon?
2. The lid is opened in interval during heating. Explain. 
3. How to make that all the magnesium ribbon has reacted completely with oxygen?

Alkali Metals with Water

Please describe the observation from the reaction shown in the video.

Crystalisation of Lead Iodide

1. What's the name of the reaction?
2. State one observation.