Question #407ab

1 Answer
anor277
Jul 18, 2017

We know that N_A ammonia molecules have a mass of 17.03*g. And thus the number of atoms in a 4.25*g mass of AMMONIA is 6.01xx10^23, i.e. "Avocado's number of atoms."

Explanation:

We work out (i) the molar quantity of ammonia:

=(4.25*g)/(17.03*g*mol^-1)=0.250*mol

And (ii), we were axed for the number of ATOMS in such a molar quantity. And because there are 4 moles of atoms in EACH mole of ammonia, we get a mole of atoms as our final answer....

... 0.75xxN_A "hydrogen atoms" + 0.25xxN_A "nitrogen atoms".

i.e. a mole of atoms in TOTAL.

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