# For 10 days, 150 g of water completely evaporated from the glass. How many molecules on average

March 27, 2021 | education

| **For 10 days, 150 g of water completely evaporated from the glass. How many molecules on average flew from the water surface in 1 s?**

Initial data: t (time of complete evaporation of water) = 10 days; m (mass of evaporated water) = 150 g.

Constants: m1 (mass of one water molecule) = 3 * 10 ^ -26 kg.

SI system: t = 10 days = 10 * 86400 s = 864000 s; m = 150 g = 0.15 kg.

1) Let’s calculate the number of molecules in 150 g of water:

N = m / m1 = 0.15 / 3 * 10 ^ -26 = 5 * 10 ^ 24 molecules.

2) Let us determine how many molecules flew out on average in 1 s:

N1 = N / t = 5 * 10 ^ 24/864000 = 5.79 * 10 ^ 18 molecules.

Answer: On average, 5.79 * 10 ^ 18 molecules flew out in 1 s.

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