A 3.60 m solution of KBr (molar mass = 119 g/mol) in water has a density of 1.26 g/mL. The molarity of this solution is:

Question

Quizplus · Accepted Answer

First, we need to calculate the number of moles of KBr present in the solution using the formula:

moles (n) = mass (m) / molar mass (M)

where
m = density (d) x volume (V)
molar mass of KBr (M) = 119 g/mol

So, substituting the given values:

m = 1.26 g/mL x 3.60 m = 4.54 g
n = 4.54 g / 119 g/mol = 0.038 mol

Now, we can calculate the molarity of the solution using the definition of molarity:

Molarity = moles of solute / liters of solution

In this case, we have 3.60 L of solution (given in the question stem), so:

Molarity = 0.038 mol / 3.60 L = 0.0106 M

However, we need to convert the units of the given concentration to match our calculated unit (mol/L). The given concentration is in g/mL, which we can convert to g/L by multiplying by 1000:

3.60 m x 1000 = 3600 g/L

Now, we can calculate the molarity using the formula:

Molarity = (given concentration / molar mass) x (1000 / density)

Molarity = (3600 g/L / 119 g/mol) x (1000 / 1.26 g/mL)
Molarity = 30.25 M / 1.26
Molarity = 23.98 M

Therefore, the correct choice is C) 3.18 M.

A 360 M Solution of KBr (Molar Mass = 119 G/mol)