Calculate the formula unit mass of sodium oxide (Na2O). Class 9

Calculate the formula unit mass of sodium oxide (Na₂O). Class 9

Question 1.

Calculate the formula unit mass of sodium oxide (Na₂O). Class 9

Answer:

Atomic mass of sodium = 23 u, oxygen = 16 u Sodium oxide has two atoms of sodium and one atom of oxygen.

Formula unit mass of sodium oxide = 2 (atomic mass of Na) + atomic mass of 0

= (2 × 23) + (1 × 16) = 62 u

Question 2.

Calculate the formula unit mass of calcium nitrate, Ca(NO₃)₂. Class 9

Answer:

Atomic mass of calcium = 40 u, nitrogen = 14 u, oxygen = 16 u

Calcium nitrate has one atom of calcium, two atoms of nitrogen and six atoms of oxygen.

Formula unit mass of sodium oxide = atomic mass of Ca +

2(atomic mass of N) + 6 (atomic mass of O)

= (1 × 40) + (2 × 14) + (6 × 16) = 164 u

Question 3.

Calculate the formula unit mass of potassium chloride (KCl). Class 9

Answer:

Atomic mass of potassium = 39 u, chlorine = 35.5 u

Potassium chloride has one atom of potassium and one atom of chlorine.

Formula unit mass of potassium chloride = atomic mass of K + atomic mass of Cl

= (1 × 39) + (1 × 35.5) = 74.5 u