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Write the balanced chemical equation for the following and identify the type of
reaction in each case.
(a) Potassium bromide(aq) + Barium iodide(aq) → Potassium iodide(aq) +
Barium bromide(s)
(b) Zinc carbonate(s) → Zinc oxide(s) + Carbon dioxide(g)
(c) Hydrogen(g) + Chlorine(g) → Hydrogen chloride(g)
(d) Magnesium(s) + Hydrochloric acid(aq) → Magnesium chloride(aq) + Hydrogen(g)
Answer
- KBr(aq) + BaI 2 (aq) → KI(aq) + BaBr 2 (s)
|
Name of the element |
No. of atoms in reactants |
No. of atoms in products |
|
Potassium |
1 |
1 |
|
Bromine |
1 |
2 |
|
Barium |
1 |
1 |
|
Iodine |
2 |
1 |
To balance Bromine,
Multiply KBr by 2
2 KBr + BaI 2 → KI + BaBr 2
|
Name of the element |
No. of atoms in reactants |
No. of atoms in products |
|
Potassium |
2 |
1 |
|
Bromine |
2 |
2 |
|
Barium |
1 |
1 |
|
Iodine |
2 |
1 |
To balance Potassium and Iodine,
Multiply KI by 2
2 KBr + BaI 2 → 2 KI + BaBr 2
|
Name of the element |
No. of atoms in reactants |
No. of atoms in products |
|
Potassium |
2 |
2 |
|
Bromine |
2 |
2 |
|
Barium |
1 |
1 |
|
Iodine |
2 |
2 |
Now, all the elements are balanced and the balanced equation is
2 KBr(aq) + BaI 2 (aq) → 2 KI(aq) + BaBr 2 (s)
In this chemical reaction two compounds react and their positive and negative ions switch places to form two new products
Thus it is a Double Displacement Reaction
- ZnCO 3 (s) → ZnO(s) + CO 2 (g)
|
Name of the element |
No. of atoms in reactants |
No. of atoms in products |
|
Zinc |
1 |
1 |
|
Carbon |
1 |
1 |
|
Oxygen |
3 |
3 |
The number of atoms of elements in reactants and products are equal. It does not require any further balancing.
Since all the elements are balanced the final balanced equation is
ZnCO 3 (s) → ZnO(s) + CO 2 (g)
In this reaction a single reactant breaks down into more than one product.
Hence it is a Decomposition Reaction .
(c) H 2 (g) + Cl 2 (g) → HCl(g)
|
Name of the element |
No. of atoms in reactants |
No. of atoms in products |
|
Hydrogen |
2 |
1 |
|
Chlorine |
2 |
1 |
To balance Hydrogen and Chlorine,
Multiply HCl by 2
H 2 + Cl 2 → 2 HCl
|
Name of the element |
No. of atoms in reactants |
No. of atoms in products |
|
Hydrogen |
2 |
2 |
|
Chlorine |
2 |
2 |
Now, all the elements are balanced and the balanced equation is
H 2 + Cl 2 → 2 HCl
In this reaction two substances react to form a single product
Hence it is a combination reaction.
(d) Mg(s) + HCl(aq) → MgCl 2 (aq) + H 2 (g)
|
Name of the element |
No. of atoms in reactants |
No. of atoms in products |
|
Magnesium |
1 |
1 |
|
Hydrogen |
1 |
2 |
|
Chlorine |
1 |
2 |
To balance Hydrogen and Chlorine,
Multiply HCl by 2
Mg + 2 HCl → MgCl 2 + H 2
|
Name of the element |
No. of atoms in reactants |
No. of atoms in products |
|
Magnesium |
1 |
1 |
|
Hydrogen |
2 |
2 |
|
Chlorine |
2 |
2 |
Now, all the elements are balanced and the balanced equation is
Mg(s) + 2 HCl(aq) → MgCl 2 (aq) + H 2 (g)
In this reaction a more reactive element takes the place of a less reactive element in a chemical compound .
Here, Magnesium is more reactive than Hydrogen
(Magnesium is above Hydrogen in the reactivity series)
Hence it is a Displacement Reaction .
