Calculate the number of: c) grams of hydrogen in 8.48 x 1022 molecules NH3

Answer 1

The question: Calculate the number of grams of hydrogen in 8.48 x 10²² molecules NH₃

First, identify your start and end points:

What are you starting out with? 8.48 x 10²² molecules NH₃

What will you end with? grams of hydrogen

*Also, notice for every 1 mole of NH_3, there are 3 moles of H

Next, familiarize yourself with the following conversions:

grams <------(A)--------> moles (B) <-------(C)-------> atoms (or particles)

(A): to convert from g to mol, use molar mass from the periodic table

(B): mole to mole conversions occur here to convert from one element to another element

(C): to convert from mol to atoms, use Avogadro's constant (6.022 x 10²³ particles / mol).

Next, find the molar mass of NH₃ and H using the periodic table. For this problem, finding the molar mass of NH₃ is unnecessary.

molar mass of nitrogen = 14.0067 g/mol

molar mass of hydrogen = 1.008 g/mol

so, molar mass of NH₃ = 14.0067 + (1.008 x 3) = 17.031 g/mol NH₃

Finally, set-up your 'rail road tracks' according to the conversion flow above. Hint: set up your 'tracks' to ensure cross cancelation of units. Don't forget to always use units and the compound you are referring to :

8.48 x 10²² molec. NH₃ | 1 mol NH₃ | 3 mol H | 1.008 g H

----------------------------------------------------------------------------------------------------- = 0.426 g H (*3 sig figs)

| 6.022 x 10²³ molec. NH₃ | 1 mol NH₃ | 1 mol H

Please plug this in to your calculator. Make sure you are using parentheses!