Answer:
It is b, 1.3 × 10 ⁻⁷
Explanation:
We know that 1 mol of H₂O is ≈ 18g
We need to get out of molecules and into moles so that we can figure out how many grams of H₂O it would be.
Starting with what we're given, let's set up our equation:
4.5×10¹⁵ molecules × (1 mol / 6.02 × 10²³molecules) × (18gH₂O / 1 mol H₂O) = 1.345 × 10⁻⁷g H₂O
This is kept to 2 significant figures and ∴ 1.3 × 10⁻⁷
Further explanation:
We start out with molecules. We cancel it out using Avagadro's number which is 6.02 × 10²³ = 1 mol. Then, we want to get into grams which means that for 1 mol of H₂O, it is equivalent to 18g using the atomic mass units ( 2(1.008) + 15.999).
Hopefully, this helps you!
