Question

Seawater is typically about 0.500 M NaCl. If the seawater has a density of 1.05 g/mL what is the salinity with respect to NaCl?

Answer 1

The concentration of grams of salt per kilogram of water (g/kg) is known as Salinity . This quantity is equal to the measure of parts salt per thousand parts water (ppt).

Given that molarity = 0.500 mole /L NaCl

Density = 1.05 g/ ml

Molar mass of NaCl is 58.4428 g/mol

Then calculate the amount of NaCL in 1.0 L water as follows:

Amount in g = number of mole * molar mass

= 0.500 mole * 58.4428 g/mol

= 29.2214 g /L NaCl

Mass of solution = volume * density

= 1000 ml * 1.05 g/ ml

= 1050 g

Or 1.050 Kg

Now calculate the amount of salt in 1.0 kg as follows:

29.2214 g / 1.050 kg *1.00 g

= 27.83 g

Thus , 27.83 grams of salt per kilogram of water is equal to 27.83 parts salt per thousand parts water (that is, 27.83 g/kg = 27.83 ppt).