George is making spaghetti for dinner. He places 4.01 kg of water in a pan and brings it to a boil. Before adding the pasta, he adds 58 g of table salt to the water and again brings it to a boil. The temperature of the salty, boiling water is °C.
It is a nice day at sea level so that pressure is 1.00 atm. Assume negligible evaporation of water. K_bfor water is 0.52°C/m.

Question

Quizplus · Accepted Answer

First, we need to calculate the boiling point elevation due to the addition of salt using the formula ΔTb = Kb * molality of salt.

Since George added 58 g of table salt to 4.01 kg of water, the molality of salt is:

molality = moles of solute / mass of solvent (in kg)
moles of salt = 58 g / 58.44 g/mol = 0.992 mol
mass of water = 4.01 kg
molality = 0.992 mol / 4.01 kg = 0.247 mol/kg

Now, we can calculate the boiling point elevation:

ΔTb = Kb * molality of salt
Kb for water = 0.52°C/m
ΔTb = 0.52°C/m * 0.247 mol/kg = 0.128°C

The boiling point elevation is 0.128°C.

The normal boiling point of water is 100°C, so the new boiling point is:

new boiling point = normal boiling point + ΔTb
new boiling point = 100°C + 0.128°C = 100.128°C

Round to three decimal places: 100.26°C.

Therefore, the best choice is C, 100.26.

George Is Making Spaghetti for Dinner