A 5.0 g sample of a pure compound containing H, C, and N contains .19 g of H and 2.22 g of C. Another smaller sample of this pure compound is analyzed. How many grams of N should be found in the new 2.0 g pure sample?
1 Answer
Explanation:
The idea here is that you need to use the amount of hydrogen and the amount of carbon found in the
Once you know the percent composition of nitrogen, you can determine the amount of nitrogen present in the
So, if your compound contains only hydrogen,
#m_"compound" = m_(H) + m_(C) + m_(N)#
This means that the
#m_(N) = "5.0 g" - "0.19 g" - "2.22 g" = "2.59 g N"#
If you divide the mass of nitrogen by the total mass of the compound and multiply the result by
#(2.59 color(red)(cancel(color(black)("g"))))/(5.0color(red)(cancel(color(black)("g")))) xx 100 = "51.8% N"#
So, what does this tell you?
For every
This means that the
#2.0 color(red)(cancel(color(black)("g compound"))) * overbrace("51.8 g N"/(100color(red)(cancel(color(black)("g compound")))))^(color(purple)("% composition of N")) = "1.036 g N"#
Rounded to two sig figs, the answer will be
#m_(N) = color(green)("1.0 g")#