# Question 06e65

Apr 27, 2017

Warning! Long Answer. The maximum number of atoms is present in (b) 0.1 g ${\text{H}}_{2}$.

#### Explanation:

(a) Atoms in ${\text{NH}}_{3}$

${\text{Moles of NH"_3 = 0.17 color(red)(cancel(color(black)("g NH"_3))) × (1 color(red)(cancel(color(black)("mol NH"_3))))/(17.03 color(red)(cancel(color(black)("g NH"_3)))) = "0.009 98 mol NH}}_{3}$

$\text{Atoms =}$

"0.009 98" color(red)(cancel(color(black)("mol NH"_3 )))× (6.023 × 10^23 color(red)(cancel(color(black)("molecules NH"_3))))/(1 color(red)(cancel(color(black)("mol NH"_3)))) × "4 atoms"/(1 color(red)(cancel(color(black)("molecule NH"_3))))

= 2.40 × 10^22 color(white)(l)"atoms"

(b) Atoms in ${\text{H}}_{2}$

${\text{Moles of H"_2 = 0.1 color(red)(cancel(color(black)("g H"_2))) × (1 color(red)(cancel(color(black)("mol H"_2))))/(2.016 color(red)(cancel(color(black)("g H"_2)))) = "0.050 mol H}}_{2}$

$\text{Atoms =}$

0.050 color(red)(cancel(color(black)("mol H"_2))) × (6.023 × 10^23 color(red)(cancel(color(black)("molecules H"_2))))/(1 color(red)(cancel(color(black)("mol H"_2)))) × "2 atoms"/(1 color(red)(cancel(color(black)("molecule H"_2))))

= 6.0 × 10^22color(white)(l) "atoms"

(c) Atoms in ${\text{O}}_{2}$

${\text{Moles of O"_2 = 0.64color(red)(cancel(color(black)("g O"_2))) × (1 color(red)(cancel(color(black)("mol O"_2))))/(32.00 color(red)(cancel(color(black)("g O"_2)))) = "0.020 mol O}}_{2}$

$\text{Atoms =}$

0.020 color(red)(cancel(color(black)("mol O"_2))) × (6.023 × 10^23 color(red)(cancel(color(black)("molecules O"_2))))/(1 color(red)(cancel(color(black)("mol O"_2)))) × "2 atoms"/(1 color(red)(cancel(color(black)("molecule O"_2))))

= 2.41 × 10^22 color(white)(l)"atoms"

(d) Atoms in $\text{HCl}$

$\text{Moles of HCl" = 0.365color(red)(cancel(color(black)("g HCl"))) × (1 color(red)(cancel(color(black)("mol HCl"))))/(36.46 color(red)(cancel(color(black)("g HCl")))) = "0.010 01 mol HCl}$

$\text{Atoms =}$

"0.010 01" color(red)(cancel(color(black)("mol HCl"))) × (6.023 × 10^23 color(red)(cancel(color(black)("molecules HCl"))))/(1 color(red)(cancel(color(black)("mol HCl")))) × "3 atoms"/(1 color(red)(cancel(color(black)("molecule HCl"))))

= 1.809 × 10^22 color(white)(l)"atoms"#

The hydrogen provides the most molecules because its atoms have such little mass that they give the most moles.