Transcript Collapsing Can
Explosive Decomposition
When a substance is touched at length it explodes with a loud bang
Purpose
To observe an explosive decomposition reaction To understand the reason the substance is explosive
Demonstration
Because the iodine atoms repel each other the molecule was unstable and detonated with the slightest vibration The chemical equation for the chemical reaction was 8 NH 3 NI 3 5 N 2 + 6 NH 4 I + 9 I 2
Concepts
1.
Decomposition Reactions 2.
Atomic Size 3.
Redox Reactions
1. Decomposition Reactions
General Form is AB A + B The substance AB has broken apart into two new substances, A and B In this demonstration AB is the substance nitrogen triiodide, NI 3
2. Atomic Size (I)
Atoms are spherical but have different sizes The relative sizes can be predicted from Periodic Trends on the Periodic Table Slight decrease in size for most part Period (horizontal row) Group (vertical row) Large increase
Atomic Size (II)
The substance in this demonstration is nitrogen triiodide, NI 3 The relative size of atomic radii are Nitrogen 0.75
Iodine 1.32 The molecule therefore looks like this • Bulky iodine atoms surround the smaller nitrogen atom • Iodine electrons repel each other making the molecule unstable
3. Redox Reactions
In a redox reaction, one substance loses electrons while another substance gains electrons “Redox” is a conventional term which is a combination of the words “reduction” AND “oxidation” In this demonstration iodide is oxidized and nitrogen is reduced
Conclusions
Nitrogen triiodide was a very unstable compound which underwent a violent decomposition reactions A knowledge of molecular structure was useful in understanding why nitrogen triiodide was explosive
Comments
Nitrogen iodide was first made in 1813 Many seriously dangerous accidents have occurred when this and similarly unstable substances have detonated