15.00 ml of a nacl solution that has a mass of 15.78 grams is placed in an evaporating dish and heated to
dryness. the remaining solid has a mass of 3.26 grams. calculate the following concentrations for the
solution: % by mass, % mass/volume, and molarity.

a = % (mass/mass) = 20.66 g

b = % (mass/volume) = 21.7 g/mL

c = Molarity = 3.7 M

Explanation:

Given data:

Volume of NaCl solution = 15.00 mL

Mass of NaCl solution= 15.78 g

After drying mass of remaining solid = 3.26 g

Concentration % (mass/mass) = ?

Concentration % (mass/volume) = ?

Concentration (molarity) = ?

Solution:

a = Concentration % (mass/mass)

% (mass/mass) = 3.26 g/ 15.78 g×100

% (mass/mass) = 20.66 g

b= Concentration % (mass/volume)

% (mass/volume) = 3.26/15 ×100

% (mass/volume) = 21.7 g/mL

c = Concentration (molarity)

We will find the number of miles first.

Number moles = mass/molar mass

Number moles = 3.26 g/58.4428 g/mol

Number moles = 0.056 mol

Now we will convert the volume in litter which is in milliliter.

15/ 1000 = 0.015 L

Molarity = number of moles/ volume in litter

Molarity= 0.056 mol / 0.015 L

Molarity = 3.7 M

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.