Question

50 points question
08. Give an example of a reaction which is both an exothermic and
combination reaction.
09. Why does milkiness disappear when carbon dioxide is passed through lime water in excess?
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Answer 1

Answer:

Explanation:

1. Combination reactions are always exothermic. For example barium metal and fluorine gas will combine in a highly exothermic reaction to form the salt barium fluoride: Another example is given by magnesium oxide combining with carbon dioxide: Often, reaction can fall into more than one category.
2. When CO2 is passed through lime-water, it turns milky due to the formation of an insoluble precipitate of Calcium Carbonate. ... The CaCO3 precipitate causes the milkiness. If you pass excess CO2 through lime-water, the CaCO3 reacts with the excess CO2 and water to form calcium hydrogen carbonate or calcium bicarbonate

Answer 2

8. Combination of barium and fluorine.
9. Because CO2 is produced.