Question

You have equal masses of different solutes dissolved in equal volumes of solution. Which of the solutes would make the solution having the highest molar concentration?
a. LiOH
b. KCl
c. KOH
d. NaOH
e. All are the same

Answer 1

Answer:

a. LiOH

Explanation:

The relationship between the parameters (mass, volume and molar concentration) mentioned in the question is given as;

Molar Concentration = (Mass / Molar Mass) * Volume

Upon calculating thr molar mass of all the compounds we have;

a)  LiOH - 6.94 + 16 + 1.01 = 24 g/mol

b) KCl - 39.098 + 35.45 = 74.5 g/mol

c) KOH - 39.098 + 16 + 1.01 = 56.1 g/mol

d) NaOH - 28.9898 + 16 + 1.01 = 46 g/mol

Picking 1 g and 1 L as the values for mass and volume. Any value would work, so long as it is constant for all compounds.

a) 1 g * 1 mol/24 g * 1/1L = 0.042 mol/L

b) 1 g * 1 mol/74.5 g * 1/1L = 0.013 mol/L

c) 1 g * 1 mol/56.1 g * 1/1L = 0.018 mol/L

d) 1 g * 1 mol/46 g * 1/1L =0.021 mol/L

LiOH has the highest molar concentration.  

Answer 2

Answer:

The highest molar concentration is in the solution of potassium chloride because it's the one, with the highest molar mass.

Explanation:

If we have the same mass and the same volume in all the solutes and solutions, we should know the molar mass for each, to calculate how many moles of solute are we having.

a. LiOH → 23.94 g/m

b. KCl → 74.55 g/m

c. KOH → 56.1 g/m

d. NaOH → 40 g/m

The highest molar mass is in option b. It will have the most moles.