How many molecules are there in 180 g of water?

univerkov | August 8, 2021 | education

Given:
M (H2O) = 180g
Find: N

Solution:

1 way: n = m / M, N = n * Na
1) M (H2O) = 18g / mol
2) n (H2O) = m / M = 180/18 = 10 mol
3) N (H2O) = n * Na = 10 * 6 * 10 ^ 23 = 6 * 10 ^ 24

Method 2: m / M = N / Na => N = m * Na / M
N (H2O) = 180 * 6 * 10 ^ 23/18 = 6 * 10 ^ 24

Answer: 6 * 10: 24

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