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Unit - 3.2 Pure Substance, Mixture and Compound — CHEMISTRY STD 7 — Question

ICSE BoardEnglish MediumSTD 7CHEMISTRYUnit - 3.2 Pure Substance, Mixture and Compound2 Marks
Question
Support with example that compound formation take place with energy changes, using water formation and iron sulphide formation.
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Answer

The chemical reaction for water formation to show energy exchange we use the formula:
The burning of methane gas in plain air or in presence of oxygen we get:
As methane burns in air it forms carbon dioxide and water
The chemical reaction for sulphide formation to show energy exchange we use the formula:
Sulphide is usually attached with sodium or Hydrogen the formation or the chemical reaction for the sulphide is
The formation of sodium sulphide is formed by sodium hydrosulphur and sodium hydroxide. Boiling off the sodium sulphide we get the conjugate sulphide

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