how many moles are in 3.4 x 10^23 molecules of H2SO4?

Answer 1

Avogadro's number (6.022 × 10²³) is defined as the number of atoms, molecules, or "units of anything" that are in a mole of that thing. So to find the number of moles in 3.4 x 10²³ molecules of H₂SO₄, divide by 6.022 × 10²³ molecules/mole and you get 0.5646 moles but there are only 2 sig figs in the given so we need to round to 2 sig figs. There are 0.56 moles in 3.4 x 10²³ molecules of H₂SO₄

Note the way this works is to make sure the units are going to give us moles. To check, we do division of the units just like we were dividing two fractions:

(molecules of H₂SO₄) = (molecules of H₂SO₄)/1 and so we have 3.4 x 10²³/6.022 × 10²³ [(molecules of H₂SO₄)/1]/[(molecules of H₂SO₄)/(moles of H₂SO₄)]. Now, invert the denominator and multiply:

moles of H₂SO₄