How many molecules are in 31.9 g of hexane?

1 Answer
David M.
Nov 8, 2016

I will assume you mean #C_6H_14#

Multiply Avagadro's Number times the amount of hexane and divide by the molar mass of hexane.

(6.022 X #10^23#) * 31.9 g / (molar mass of hexane)

Explanation:

Note: If you were talking about Cyclohexane, the formula would be #C_6H_12#

The formula for obtaining the number of particles given the amount of sample in grams follows this formula:

(6.022 X #10^23#) X (grams of sample) / (molar mass of hexane)

In performing a unit conversion, you are actually doing the same thing to the units that you are doing to the values.

(particles / mole) * (g) / (g/mole)

enter image source here Source: Generated by David M. Using Microsoft PowerPoint

The moles and the grams cancel, leaving an answer in particles.

You may ask why I say "particles" and not "molecules"? The reason is so the SAME calculation may be performed for ionic compounds, ions, or other types of chemical identities.

Related questions
See all questions in Unit Conversions
Impact of this question
4695 views around the world
You can reuse this answer
Creative Commons License