Question

7.95 x 1023 (7.95e+23) molecules of ammonia (NH3) is what mass in grams?

Answer 1

ANSWER:

Number of molecules of ammonia = 7.95 x 10²³ molecules

molecular mass of ammonia = 17.031 g/mol

Now,

6.022 x 10²³ molecules of ammonia = 1 mole of ammonia

1 molecule of ammonia = {1/(6.022 x 10²³⁾} moles of ammonia

= 1.66 x 10^-24 moles of ammonia

So, 7.95 x 10²³ molecules of ammonia =  7.95 x 10²³ x1.66 x 10^-24 moles of ammonia

= 1.32 moles of ammonia

And,

Mass of ammonia = Number of moles of ammonia x molecular mass of ammonia

= 1.32 mol x 17.031 g/mol

= 22.481 g

Hence, mass of 7.95 x 10²³ molecules of ammonia is 22.481 grams.