How to solve for moles when given molecules?

A thimble of water contains 4.0 x 1021 molecules. The number of moles of H2O is:

2.4 x 1023

6.6 x 10-23

2.4 x 1045

2.4 x 10-23

6.6 x 10-3

4 Answers

  • Divide #molecules by Avogadro's number, 6.02 x 10^23.

    4.0x10^21 / 6.02x10^23 = 6.6x10^-3.

  • 1 mol = 6.022 x 10^23 molecules

    (This is Avogadro's number)

    so 4.0 x 10^21 molecules x (1 mol / 6.022 x 10^23 molecules) = 6.6 x 10^-3 moles

  • 6.022 * 10^23 molecules = 1 mole

    1 molecule = 1 / (6.022 * 10^23) mole

    thus 4.0 x 1021 molecules = (4.0 x 10^21) / (6.022 * 10^23)

    = 0.0066423 moles or 6.64 * 10^-3 moles

  • (a) PV = nRT they supply you T, P, and V. go look up R on your e book. do not neglect to covnert T to kelvins. resolve for n, the style of moles. (b) multiply your style for (a) by skill of Avocado's style (or Avogadro's I neglect--look it up in case you don't be conscious of it).

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