Question

What volume of a 0.500 M solution of HBr is needed for a reaction thatrequires 32.5 g of HBr?

Answer 1

The formula of molarity is the following:

`\text{Molarity}=\frac{\text{moles of solute}}{liters\text{ of solution}}.`

But, we need to calculate the number of moles in 32.5 g of HBr using its molar mass which is 80.9 g/mol. The conversion would be:

`32.5\text{ g HBr}\cdot\frac{1mol\text{ HBr}}{80.9\text{ g}}=0.402\text{ moles HBr.}`

Now that we have the number of moles, we can solve for 'liters of solution' from the formula and replace the values of molarity (0.500 M) and moles (0.402 moles):

`\begin{gathered} \text{liters of solution=}\frac{mole\text{s of solute}}{Molarity}, \\ \text{liters of solution=}\frac{0.402\text{ moles}}{0.500\text{ M}}, \\ \text{liters of solution=0.804 L.} \end{gathered}`

The answer is that the volume required for a 0.500 M of 32.5 g of HBr is 0.804 L.