Question

How many milliliters of 0.500 M HBr would be required to react with 40.0 mL of 0.300 M Ca(OH)2?

Answer 1

48dm³

Step-by-step explanation:

Given reaction:

Ca(OH)₂ + 2HBr → CaBr₂ + 2H₂O

Parameters:

Concentration of HBr = 0.5M

Volume of Ca(OH)₂ = 40mL

Concentration of Ca(OH)₂ = 0.3M

Solution:

To solve this problem, we are going to use the mole concept. We solve from the known specie to the unknown.

We first find the number of moles of the known specie which is the Ca(OH)₂ ;

number of moles = concentration x volume

number of moles = 0.3 x 40 x 10⁻³ = 0.012moles

From the reaction equation;

1 mole of Ca(OH)₂ requires 2 moles HBr

0.012 moles of Ca(OH)₂ will require 0.012 x 2 = 0.024moles of HBr

Now,

To find the volume of HBr;

Volume =
`(number of moles )/(concentration)`

Volume =
`(0.024)/(0.5)` = 0.048dm³

In mL;

Volume 0.048 x 1000 = 48dm³