How many grams of H2O is 4.5 x 10 15 molecules? *
13 points
O 1.3 x 1039
O 1.3 x 10 -7
O 1.5 x 10 38
O1.5 x10 39
O Other

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!

The law of conservation of mass states that a mass of an object or the amount of matter composed inside an object or thing will not change unless it is added or removed of the matter that is contained in the object itself.