1. Upon being brought together a lump of white phosphorus and chlorine gas react in flame. Reaction of White Phosphorus and Chlorine

2. Purpose n To observe a combination reaction between two non-metals n To understand that a combination reaction is a redox reaction

3. Demonstration n There was a brief induction period before the phosphorus began to burn in the chlorine n The white coating on the inside of the florence flask was the product of the reaction, solid phosphorus pentachloride

4. Concepts 1.Allotropes 2.Covalent Compounds 3.Combination Reactions

5. 1.Allotropes n Different forms of the same element n Carbon graphite diamond n Phosphorus white phosphorus P 4 red phosphorus

6. 2.Covalent Compounds n As opposed to ionic compounds n Composed of two or more non- metals n Examples carbon + oxygen phosphorus + oxygen phosphorus + chlorine n Shared electrons between the elements are themselves what we call covalent “bonds” CO CO 2 P 4 O 10 PCl 5

7. 3.Combination Reactions n A + BC n P 4 (s) + Cl 2 (g) PCl 5 (s) n Oxidation Number Changes StartFinishEffect P 0 5+loses electrons Cl 0 1-gains electrons 410 is oxidized is reduced

8. Conclusions n Two non-metals reacted to form a covalent compound n The reaction was both n “Burning” occurred without oxygen as long as another oxidizing agent is present a combination reaction a redox reaction

9. Comments n Although the element phosphorus is essential for life its elemental form is highly reactive and poisonous n White phosphorus is stored under water to prevent it from reacting with oxygen in the air n Red phosphorus is found in matches and is relatively air stable compared to white phosphorus P 4 +O 2 P 4 O 10