Question

What mass is needed to prepare1×10^20 atoms in nitrogen


solve it step by step

Answer 1

The first thing to do here is to determine the mass in grams of 2.33⋅1020 atoms of oxygen.

To do that, use Avogadro's number to convert the number of atoms to moles, the molar mass of oxygen to convert the moles to grams.

So, Avogadro's number, which acts as the definition of a mole, tells you that in order to have one mole of oxygen, you need to have 6.022⋅1023 atoms of oxygen.

In your case, the sample will be equivalent to

2.33⋅1020atoms of O⋅1 mole O6.022⋅1023atoms of O

=3.869⋅10−4moles O

Now, oxygen has a molar mass of 15.9994 g mol−1 as listed in the Periodic Table of Elements

This means that your sample will have a mass of

3.869⋅10−4moles O⋅15.9994 g1mole O

=6.190⋅10−3g

Finally, you can convert the mass from grams to nanograms by using the conversion factor

∣∣ ∣∣¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯aa1 g=109ngaa∣∣−−−−−−−−−−−−−−−

You will end up with

6.190⋅10−3g⋅109ng1g=∣∣ ∣∣¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯aa6.19⋅106ngaa∣∣−−−−−−−−−−−−−−−

i hope this can help you