Answer:
260.34g
Explanation:
First, you need to know what angelic acid is comprised of. It is written as C₅H₈O₂.
In order to solve for the mass of 2.6 moles of angelic acid, you need the mass of 1 mole of angelic acid. This can be found by adding the masses from the periodic table, like shown below:
5 carbon atoms = (5)(12.01g) = 60.05g
8 hydrogen atoms = (8)(1.01) = 8.08g
2 oxygen atoms = (2)(16) = 32g
angelic acid = 60.05 + 8.08 + 32 = 100.13g
Then, set up a basic stoichiometric equation and solve. The units should cancel out.

Answer:

Explanation:
Assume you are using 1 L of water.
Then you are washing 4 L of salty oil.
1. Calculate the mass of the salty oil
Assume the oil has a density of 0.86 g/mL.

2. Calculate the mass of salt in the salty oil

3. Calculate the mass of salt in the spent water

4. Mass of salt remaining in washed oil
Mass = 172 g - 150 g = 22 g
5. Concentration of salt in washed oil

I believe it was John Newlands.
Hope that helped
I think thats the answer but feel free to check my work