The mass of water is 40g. How many molecules are there?

univerkov | November 19, 2020 | education

Let’s write down given:
m (H2O) = 40g
To solve this problem, we will use the formula:
n = m / M, N = n * Na (where Na is Avogadro’s number)
M (H₂O) = 1 * 2 + 16 = 18 (g / mol)
n (H₂O) = m (H2O) / n (H2O) = 40/18 = 2.22 (mol)
N (H₂O) = n (H₂O) * Na = 2.22 * 6.02 * 10 ^ 23 = 13.36 * 10 ^ 23 (molecules)

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