What is the number of molecules in 1.00 mol of iodine crystals?

Is the answer 6.022 x 10^25 molec. of I2 ? or do I have double this answer, given that I2 is a diatomic molecule??

1 Answer
Jan 21, 2017

Answer:

#6.02 * 10^(23)#

Explanation:

The problem wants to make sure that you are familiar with the definition of one mole of a given substance.

In this case, you're dealing with a covalent compound, so you're looking for the number of molecules of iodine, #"I"_2#, present in exactly #1.00# moles of iodine crystals.

Now, a mole is defined as very, very large collection of particles. In order to have #1.00# moles of iodine crystals, you need to have exactly #6.022 * 10^(23)# molecules of iodine.

#color(blue)(ul(color(black)("1 mole I"_2 = 6.022 * 10^(23)"molecules I"_2# #-># Avogadro's constant

In your case, you will have

#"1.00 moles I"_2 = 6.02 * 10^(23)"molecules I"_2#

The answer must be rounded to three sig figs, the number of significant figures you have for the number of moles of iodine crystals.

Notice that each iodine molecule contains #2# atoms of iodine, #2 xx "I"#, which means that #1# mole of iodine molecules contains #2# moles of iodine atoms.

In #1.00# moles of iodine molecules you have #2# moles of iodine atoms, or

#overbrace(6.022 * 10^(23)color(red)(cancel(color(black)("molecules I"_2))))^(color(blue)(= "1.00 moles I"_2)) * "2 atoms of I"/(1color(red)(cancel(color(black)("molecule I"_2)))) = overbrace(1.20 * 10^(24)"atoms of I")^(color(purple)(="2.00 moles of I"))#

Once again, the answer must be rounded to three sig figs.