Question

(2) Calculate the formula mass (a.m.u) of the following? Al,O3, MgCl2, NaCl, KNO,
how to solve it
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Answer 1

Answer:

Al =27 O3= 48 Mgcl2= 96 Nacl = 58.5 Kno= 70

Answer 2

Given:

The compounds whose atomic masses are already known.

To find:

The formula mass/ molecular mass of the given elements and compounds.

Formula to be used:

Only simple addition and multiplication are to be used.

Solution:

• Al: The element aluminium is given as an atom and has an atomic mass of 27u.
• $O_{3}$: The element ozone is given, and the atomic mass of oxygen is 16. So, 16 x 3 = 48u.
• $MgCl_{2}$: Compound magnesium chloride is given; the mass of magnesium is 24 and that of chlorine is 35.5. So, by solving a simple equation, we can find the solution. 24 + 35.5 x 2 = 95u.
• NaCl: Compound sodium chloride is given; the mass of sodium is 23 and chlorine has 35.5. So, the equation formed will be, 23 + 35.5 = 58.5u.

Final answer:

The formula/ molar mass calculated are as follows:

Aluminium: 27u

Ozone: 48u

Magnesium chloride: 95u

Sodium chloride: 58.5u