Question

1. A sample of magnesium consists of 1.92 x 10^22Mg atoms. What is the mass
of the sample in grams? (atomic mass = 24.3 amu)​

Answer 1

Answer:-

0.78 g

Explanation:-

Here, atomic mass of Magnesium is given as 24.3 amu. We know that, molar mass of an element is the atomic mass in grams.

Thus, molar mass of Magnesium is 24.3g.

Firstly, let's calculate the number of moles present in 1.92×10²² atoms of Mg.

• Avogadro number = 6.022×10²³

No of moles:-

= No of particles/Avogadro number

= 1.92×10²²/6.022×10²³

= 0.318/10

= 0.0318 moles [ approximately ]

Now, mass of 0.031 moles of Magnesium:-

= No of moles × Molar mass

= 0.0318 × 24.3

= 0.78 g

Thus, mass of the sample is 0.78g .

Answer 2

Answer:-

0.78 g

Explanation:-

Here, atomic mass of Magnesium is given as 24.3 amu. We know that, molar mass of an element is the atomic mass in grams.

Thus, molar mass of Magnesium is 24.3g.

Firstly, let's calculate the number of moles present in 1.92×10²² atoms of Mg.

• Avogadro number = 6.022×10²³

No of moles:-

= No of particles/Avogadro number

= 1.92×10²²/6.022×10²³

= 0.318/10

= 0.0318 moles [ approximately ]

Now, mass of 0.031 moles of Magnesium:-

= No of moles × Molar mass

= 0.0318 × 24.3

= 0.78 g

Thus, mass of the sample is 0.78g .