Chemical reactions and Equations long 6 Flashcards
In the double displacement reaction between aqueous Kl and aqueous Pb[NO^3], a yellow precipitate of lead iodine is formed. While performing if lead nitrate is not available, which of the following can we use.
1] Lead sulphate [insoluble]
2] Lead acetate
3] Ammonium nitrate
4] Potassium sulphate
Because we need a compound that contains lead in order to obtain lead iodide, ammonium nitrate and potassium sulphate are ruled out. Because lead sulphate is insoluble, it cannot be used; therefore, the correct answer is lead acetate.
You might have noticed that when copper powder is heated in a china dish, the surface of copper powder becomes coated with black colour substance.
(i) How has this black-coloured substance formed?
(ii) What is that black substance?
(iii) Write the chemical equation of the reaction that takes place.
(i) The surface of copper powder becomes coated with a black-coloured substance because of the process called surface oxidation. This is because the copper powder present in the china dish reacts with the atmospheric oxygen and forms copper oxide. The compound formed by copper oxide is generally black in colour and thus, the surface of copper powder is coated with this .
(ii) The black substance formed on the surface of copper powder is copper oxide.
(iii) Required chemical equation of the reaction taking place:
2Cu+O2→heat,Δ2CuO
When metal X is treated with a dilute acid Y, then a gas Z is evolved which burns readily by making a little explosion.
(a) Name any two metals which can behave like metal X.
(b) Name any two acids which can behave like acid Y.
(c) Name the gas Z.
(d) Is the gas Z lighter than or heavier than air ?
(e) Is the reaction between metal X and dilute acid Y, exothermic or endothermic ?
(f) By taking a specific example of metal X and dilute acid Y, write a balanced chemical equation for the reaction which takes place. Also indicate physical states of all the reactants and products.
(a) Zinc and Iron
(b) Dilute hydrochloric acid and Dilute sulphuric acid
(c) Hydrogen
(d)Lighter than air
(e)Exothermic
(f)Suppose metal X is zinc (Zn) and acid Y is dilute hydrochloric acid (HCl); Zn[s] + 2HCl[aq]→ZnCl^2[aq] + H^2[g]
