How many grams of nitrogen are contained in a sample of C4H9N3O2 that also contains 9.42 x 1024 hydrogen atoms?

Answer 1

first you want to find the moles of hydrogen by dividing by Avogadro's number

9.42 x 10^24 / (6.022 x 10^23 atoms/mol) = 15.64 mol

then you can convert over to the moles of nitrogen using the ratio of atoms from the subscripts

15.64 mol H x 3 mol N / 9 mol H = 5.22 mol

finally then you can convert that over to grams by multiplying by the molar mass

5.22 mol N x (14.01 g/mol) = 73.05

meaning that this sample also contains 73.05 grams of nitrogen

Answer 2

Hi Rachel,

In C4H9N3O2, hydrogen is present at a ratio of 3 times more than nitrogen.

So if there are 9.42 x 10^(24) hydrogen atoms, then there are 3.14 x 10^(24) nitrogen atoms (I get this by dividing by 3).

Now that we know how many nitrogen atoms we have, we can find the numbers of moles (by multiplying Avogadro's number) and then we can find the number of grams by multiplying nitrogen's molar mass.

Nitrogen's molar mass is 14 g/mol

3.14 x 10^(24) nitrogen atoms * 1 mol / (6.022 x 10^(23) atoms) * 14 g / 1 mol = 72.99 g of nitrogen

Hope this helps! Have a great day!