Q. 203.8( 5 Votes )
What happens when:
(a) manganese dioxide is heated with aluminium powder?
(b) iron (III) oxide is heated with aluminium powder?
(a) When manganese dioxide (MnO2) is heated with aluminium powder, displacement reaction takes place, and manganese is obtained as the product along with aluminium oxide. It is an exothermic reaction and hence Mn is obtained in molten form.
3MnO2(s) + 4Al(s) → 3Mn(l) + 2Al2O3(s) + heat
(b) Iron (III) oxide is heated with aluminium powder to form iron and aluminium oxide. This is another example of a displacement reaction and is highly exothermic. This reaction is also known as thermit reaction.
Fe2O3(s) + 2Al(s) → 2Fe(l) + Al2O3(s) + Heat
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i. What is observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube?
ii. What type of reaction is this?
iii. Write a balanced chemical equation to represent the above reaction.
A brown substance ‘X’ on heating in air forms a substance ‘Y’. When hydrogen gas is passed over heated ‘Y’, it again changes back into ‘X’.
i. Name the substance ‘X’ and ‘Y’
ii. Name the type of chemical reactions occurring during both the changes.
iii. Write the chemical equations of the reactions.Xam idea - Science