Question

What is the mass in grams of 4.03 x 10(23) H2 molecules at STP?

Answer 1

The asnwer is `1.34grams`.

One mole of diatomic hydrogen, `H_2`, has `6.022 * 10^23` `H_2` molecules, and weighs approximately `2grams`.

However, just by looking at the number of `H_2` molecules given, you can estimate that this amounts to less than `1` mole.

`4.03 * 10^23` molecules * (`1` mole)/(`6.022 * 10^23`molecules) = `0.67` moles of `H_2`.

Therefore, the mass is equal to

`0.67` moles * `2 g/(mol) = 1.34 grams` of `H_2`.