How many molecules are in 3 moles of H_2SH2S?

1 Answer
Stefan V.
Jun 27, 2016

1.8 * 10^(24)"molecules"1.8⋅1024molecules

Explanation:

As you know, a mole is simply a very, very large collection of molecules.

In order to have one mole of a molecular substance, you need to have 6.022 * 10^(23)6.022⋅1023 molecules of that substance ->→ this is known as Avogadro's number and it can be used as a conversion factor to go from number of molecules to moles and vice versa.

color(blue)(|bar(ul(color(white)(a/a)"1 mole" = 6.022 * 10^(23)"molecules"color(white)(a/a)|)))∣∣ ∣∣¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯aa1 mole=6.022⋅1023moleculesaa∣∣−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

Now, you want to know how many molecules are present in 33 moles of hydrogen sulfide, "H"_2"S"H2S.

According to Avogadro's number, 11 mole of hydrogen sulfide contains 6.022 * 10^(23)6.022⋅1023 molecules of hydrogen sulfide, which means that 22 moles will contain

3 color(red)(cancel(color(black)("moles H"_2"S"))) * overbrace((6.022 * 10^(23)"molecules H"_2"S")/(1color(red)(cancel(color(black)("mole H"_2"S")))))^(color(blue)("Avogadro's number")) = color(green)(|bar(ul(color(white)(a/a)color(black)(1.8 * 10^(24)"molecules H"_2"S")color(white)(a/a)|)))3moles H2S⋅Avogadro's number6.022⋅1023molecules H2S1mole H2S=∣∣ ∣∣¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯aa1.8⋅1024molecules H2Saa∣∣−−−−−−−−−−−−−−−−−−−−−−−−

I'll leave the answer rounded to two sig figs.

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