Percentage of isotopes in 35/17 Cl and 37/17 Cl

Explanation:

Average atomic mass of Chlorine = 35.45 amu

The percentage of isotopes is the percentage abundance.

This is given by;

Average atomic mass = (Mass of isotope * Percentage abundance of 35/17 Cl) + (Mass of isotope * Percentage abundance 37/17 Cl)

Let percentage abundance of 35/17 Cl = x

Then percentage abundance of 37/17 Cl = 1 - x

Putting the values in the equation;

35.45 = (35 * x)   + (37 * (1-x))

35.45 = 35x + 37 - 37x

35.45 - 37 = 35x - 37x

- 1.55 = -2x

x = 1.55 / 2 = 0.775

Percentage abundance of 35/17 Cl = 0.775 * 100 = 77.5%

Percentage abundance of 37/17 Cl = (1 - 0.775) * 100 = 22.5%

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.