Answer:
9.77 × 10⁹ molecules
Explanation:
Since the density of water is 1 g/cm³ = 1000 g/L
So, we find the mass of sea water in 250 mL = 0.250 L
We know density = mass/volume
mass = density × volume = 1000 g/L × 0.250 L = 250 g
Now we calculate the number of moles of sea water in 250 g, 250 mL of sea water.
number of moles n = mass of sea water,m/molar mass of water, M
molar mass of water, M = 18 g/moL
n = m/M = 250 g/18 g/mol = 13.89 mol
We now calculate the number of molecules present in the 250 mL of sea water.
n = N/N' where N = number of molecules, N' = avogadro's number = 6.022 × 10²³/mol
So,N =nN' = 13.89 mol × 6.022 × 10²³/mol = 8.36 × 10²⁴ molecules
Now, the volume of the ocean is 1.337 × 10¹⁸ m³ = 1.337 × 10¹⁵ L
Since the 250 mL sea water is mixed with the ocean, the number of molecules per liter is 8.36 × 10²⁴ molecules/1.337 × 10¹⁵ L = 6.25 × 10⁹ molecules/L
If we now take 250 mL out of the ocean, the number of molecules in this 250 mL will be 6.25 × 10⁹ molecules/L × 250 mL = 6.25 × 10⁹ molecules/L × 0.250 L = 9.77 × 10⁹ molecules.
So, we have 9.77 × 10⁹ molecules of pink molecules in the 250 mL after mixing in the ocean.
