Question

Question #19f01

Answer 1

`%"mass NaOH" = 32%`

Explanation:

I'll assume the percentage concentrations are those by mass.

We know:

• there are `8.6` `"kg"` of water

• there are `3.4` `"kg"` of caustic soda

Since the caustic soda is `92.7%` `"NaOH"` by mass, the mass of `"NaOH"` in solution is

`(0.972)(3.4color(white)(l)"kg") = 3.30` `"kg NaOH"`

The percent by mass in solution is

`%"mass NaOH" = "mass NaOH"/"mass solution"xx100%`

`= (3.30color(white)(l)"kg")/(underbrace(3.4color(white)(l)"kg")_"caustic soda" + underbrace(8.6color(white)(l)"kg")_"water")xx100%`

`= color(red)(32%`

rounded to `2` significant figures.