Question

Write the formula and names of compounds formed by


​

Answer 1

Answer:

NaHCO3→sodium bicarbonate

K2CO3→potassium carbonate

CuSO4→copper sulphate

CuO→copper oxide

Na2SO4→sodium sulphate

(NH4) 2 CO3→ ammonium carbonate

Answer 2

Answer: The chemical formula and names of the compounds are given as:

(a) NaHCO₃ and Sodium Bicarbonate

(b) K₂CO₃ and Potassium Carbonate

(c) CuSO₄ and Copper Sulphate

(d) CuO and Copper Oxide

(e) Na₂SO₄ and Sodium Sulphate

(f) (NH₄)₂CO₃ and Ammonium Carbonate

Let's discuss how to do such type of questions.

Explanation:

What exactly is a chemical formula?

A chemical formula identifies the components that comprise the compound as well as the number of atoms of each element in the complex's smallest unit, whether a molecule or a formula unit.

• Knowing the names of elements, as well as a few basic rules, allows us to name simple compounds given a chemical formula.
• We can also reverse the procedure.
• That is, if we know the compund's name, we should be able to write down the chemical formula.

Writing a chemical formula for a binary compound using valency

A chemical formula represents the proportions of the various components in a compound by mass.

A binary compound is made up of only two distinct components. Valencies may be used to write binary compound formulae since both sorts of atoms in the compound must

• lose
• acquire or
• share the same amount of electrons.

To write a binary compound's chemical formula:

1. Determine the valencies of the two current items.
2. Create a chemical formula in which the sums of the valencies of the two elements equal one.
3. Calculate the lowest common multiple of the two valencies.
4. If a metal is present, it should always come first in the formula.

For example, let us solve the question for better understanding.

(a) Na⁺ and HCO₃⁻

Valency of elements:

Na = +1

HCO₃ = -1

Using criss-cross method,

NaHCO₃ is the chemical formula and its name is Sodium Bicarbonate.

(b) K⁺ and CO₃²⁻

Valency of elements:

K = +1

CO₃ = -2

Using criss-cross method,

K₂CO₃ is the chemical formula and its name is Potassium Carbonate.

(c) Cu²⁺ and SO₄²⁻

Valency of elements:

Cu = +2

SO₄ = -2

Using criss-cross method,

CuSO₄ is the chemical formula and its name is Copper Sulphate.

(d) Cu²⁺ and O²⁻

Valency of elements:

Cu = +2

O = -2

Using criss-cross method,

CuO is the chemical formula and its name is Copper Oxide.

(e) Na⁺ and SO₄²⁻

Valency of elements:

Na = +1

SO₄ = -2

Using criss-cross method,

Na₂SO₄ is the chemical formula and its name is Sodium Sulphate.

(f) NH₄⁺ and CO₃²⁻

Valency of elements:

NH₄ = +1

CO₃ = -2

Using criss-cross method,

(NH₄)₂CO₃ is the chemical formula and its name is Ammonium Carbonate.

Hope, now the concept is clear.