Question

what is the mass of 4.86 x 10^21 molecules of ethanol, C2H5OH?

Answer 1

step 1. We first calculate the number of moles present in Ethanol ,then in the next step we shall move to calculate the mass of ethanol present.

We know that,

6.023*10^23 molecules of ethanol will have = 1 mol.

So, 4.86*10^21 molecules of ethanol will have = 4.86*10^21/ 6.023*10^23 moles

=0.8069 * 10^ -2 moles.

= 0.008069 moles.

Step 2. In the step ,we shall calculate the mass of ethanol.

We know that ,No. Of Mole = mass in gm/ molar mass

Therefore, Mass = NO. Of mole * Molar mass

= 0.008069 mole * 46.07 g/mol

=0.3717 g

Please upvote