Question

Analysis of chlorophyll show that it contains 2.68%Mg . No. Of magnesium atoms present in 2.4g of chlorophyll is?

Answer 1

if 2.68% by mass, then solution is correct☺☺

Answer 2

Answer: $15.05\times 10^{20}$ molecules

Explanation:

Given: mass of chlorophyll = 2.4 g

But as chlorophyll contains 2.68 % of Mg by mass, amount of Mg=$\frac{2.68}{100}\times 2.4=0.06g$

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\textMolar mass}}$

Mass of Mg = 0.06  g

Molar mass of Mg= 24 g/mol

Putting values in above equation, we get:

$\text{Moles}=\frac{0.06g}{24g/mol}=2.5\times 10^{-3}mol$

According to Avogadro's law, 1 mole of every substance contains avogadro's number $(6.023\times 10^{23})$ of particles.

Thus $2.5\times 10^{-3}$ mol of Mg contains=$\frac{6.023\times 10^{23}}{1}\times 2.5\times 10^{-3}=15.05\times 10^{20}$ atoms of Mg.