Question

What volume of a 0.716 M KBr solution is needed to provide 30.5 g of
KBr?

Answer 1

Answer:

Answer is: volume of kbr is 357 ml.c(kbr) = 0,716 m = 0,716 mol/l.m(kbr) = 30,5 g.n(kbr) = m(kbr) ÷ m(kbr).n(kbr) = 30,5 g ÷ 119 g/mol.n(kbr) = 0,256 mol.v(kbr) = n(kbr) ÷ c(kbr).v(kbr) = 0,256 mol ÷ 0,716 mol/l.v(kbr) = 0,357 l · 1000 ml/l = 357 ml.

Answer 2

The answer is 358 mL.

Explanation:

Given: Molarity of KBr, M = 0.716 mol/L, Mass of KBr, m = 30.5 g

To be found: Volume, V

Formula to be used: $M = \frac{n}{V}$ and $n = \frac{m}{Molar mass}$ where

• M is molarity
• n is the number of moles
• V is the volume (in L)
• m is mass(in g)

Solution:

First, we would find the number of moles

• Molar Mass of KBr$= 39 + 79.9 = 118.9 g/mol$

• n $= \frac{30.5}{118.9} = 0.256$

Now, Volume  $V = \frac{n}{M}$

V $= \frac{0.256}{0.716} =0.358 L = 358 mL$

Thus, 358 mL would be needed.