Question

Calculate the mass (in grams) of 3.85 x 1024 carbon atoms.

Round your answer to two decimal places.

Answer 1

You can get to the answer in two steps:

calculate: 3.40⋅1022 atoms = x mol ?

using Avogadro's constant.

calculate: x mol = ? grams,

using the atomic mass of Helium.

Step 1

Avogadro's constant says that 1 mole of any atom contains 6.022⋅1023 atoms. In this case you have 3.40⋅1022 atoms:

3.40⋅1022atoms6.022⋅1023atomsmol = 5.65⋅10−2mol

Step 2

The atomic mass of helium (He) will give you the weight of one mole of this molecule: 1 mol = 4.00 gram:

4.00gmol⋅5.65⋅10−2mol = 0.226g

So the 3.40⋅1022 helium atoms weigh 0.226 gram.