# How many grams of salt must be added to 300g of water to increase its boiling point by 5°C?

##### 1 Answer

You must add 86 g of salt.

#### Explanation:

The formula for boiling point elevation is

#color(blue)(|bar(ul(ΔT_"b" = iK_"b"m)|)#

where

#i# is the van't Hoff factor#ΔT_"b"# is the boiling point elevation#K_"b"# is the boiling point elevation constant#m# is the molality of the solution

We can solve the equation for the molality of the solution.

In this problem,

∴

Next, we calculate the moles of

The formula for molality is

#color(blue)(bar(ul(|color(white)(a/a) "Molality" = "moles of solute"/"kilograms of solvent"color(white)(a/a)|)))" "#

∴

Finally, convert moles of