What volume of distilled water must be added to 112 mL of 0.750 mol/L hydrobromic acid solution...


What volume of distilled water must be added to 112 mL of 0.750 mol/L hydrobromic acid solution in order to dilute it to a concentration of 0.250 mol/L?

Hydrobromic Acid:

Hydrobromic acid ({eq}\rm HBr(aq) {/eq}) is a strong acid, which means it fully dissociates into ions when dissolved in water. It is often used for the industrial production of metal bromides.

Answer and Explanation: 1

The question gives us the initial volume (112 mL) and concentration (0.750 mol/L) of a hydrobromic acid solution. It asks how much distilled water must be added to dilute it to a final concentration of 0.250 mol/L. To solve this, we will first find the volume of the final solution using the dilution equation:

{eq}\rm c_1V_1 = c_2V_2{/eq}


{eq}\rm c_1{/eq} is the initial concentration
{eq}\rm V_1{/eq} is the initial volume
{eq}\rm c_2{/eq} is the final concentration
{eq}\rm V_2{/eq} is the final volume

Rearranging the formula to solve for {eq}\rm V_2{/eq} and substituting in the values:

{eq}\begin{align} \rm V_2 =& \rm \dfrac{c_1V_1}{c_2}\\ &= \rm \dfrac{(0.750\:mol/L)(112\:mL)}{0.250\:mol/L}\\ &= \rm 336\:mL \end{align} {/eq}

Now that we know the final volume of the solution will be 336 mL, we can subtract the initial volume of the solution from this to determine how much water needs to be added:

{eq}\rm 336\:mL - 112\:mL = 224\:mL {/eq}

Therefore we must add 224 mL of distilled water.

Learn more about this topic:

Calculating Dilution of Solutions


Chapter 8 / Lesson 5

Learn what a solution is and how to properly dilute a new solution from a stock solution. Learn the dilution equation that combines molarity, the volume of stock solution and desired solution to determine how much stock solution is needed for the new solution.

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