Question

Please show your work

a) At an elevated location with an atmospheric pressure of 0.980 atm, how much table salt (NaCl in grams) do I have to add to 1 L of water in order to be able to boil eggs at 100°C?

Answer 1

a) Pressure () = 0.980 atm

Temperature = 100^oC = 373K

Gas constant (R) = 0.0821l.atm/(mol.K)

i = 2 ( Vant hoff factor: Number of ions formed)

Let M be the molarity of solution

According to Osmotic Pressure

= i *M*R*T

0.980atm = 2*M*(0.0821l.atm/(mol.K))*373 K

M = 0.016

Molarity = moles/ Volume of water

0.016 = moles/ 1L

Moles of NaCl = 0.016 mol

Moles of NaCl = mass/ molar mass of NaCl = mass /58.44 g/mol

0.016 mol =  mass /58.44 g/mol

Mass = 0.935 g

So, Amount NaCl added = 0.935g