Question

Find the number of atoms present in 10g of NH₃
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please give answer in numericals ​

Answer 1

Answer:

We must start by calculating the mass of a single molecule of  NH3 . By looking at the Periodic Table, we can see that an atom of Nitrogen (N) has an atomic weight of 14.007 atomic mass units. We can also see that an atom of Hydrogen (H) has an atomic mass of 1.008 atomic mass units. (Notice that I am choosing to use atomic weight instead of atomic mass because we do not know exactly which isotopes we are dealing with and are therefore better off going for an average answer.) Given these two atomic weights, we can see that the mass of 1 molecule of  NH3  is  14.007+1.0081×3  atomic mass units. This sums to 17.031 atomic mass units.

Now, let us use the conversion rate between atomic mass units and grams, approximately  6.02×1023 , otherwise known as Avogadro’s Number. Since this is the conversion factor, we can say that since 1 molecule of  NH3  has a mass of 17.031 atomic mass units,  6.02×1023  molecules of  NH3  has a mass of 17.031 grams.

Since only 10 grams of  NH3  are present in the problem, we see that 10 divided by 17.031 is fraction of  6.02×1023  which is present, so the total number of present molecules is  1017.031(6.02×1023) , or  3.53×1023 .

Since each molecule of  NH3  contains 4 atoms, the total number of atoms, as asked for by the problem, is  1.41×1024 .

Explanation: