Question

How many milliliters of 0.125 M Ba(OH)2(aq) must be used to produce 5.5 moles of water? Please balance the equation before solving the problem.

Answer 1

You must use 22 L of the barium hydroxide solution.

Explanation:

There are three steps involved in this stoichiometry problem:

1. Write the balanced chemical equation
2. Use the molar ratio from the balanced equation to calculate the moles of `"Ba(OH)"_2`
3. Calculate the volume of `"Ba(OH)"_2`

Step 1. Write the balanced chemical equation.

Let's assume you are using `"HCl"` as the acid.

`M_r:color(white)(mmmmmmmmmmmmmmmll) 18.02`
`color(white)(mmm)"Ba(OH)"_2 + "2HCl" →"BaCl"_2 + "2H"_2"O"`

Step 2. Calculate the moles of `"Ba(OH)"_2`

The molar ratio from the balanced equation is

`"Ba(OH)"_2:"H"_2"O"= 1:2`.

`"Moles of Ba(OH)"_2 = 5.5 color(red)(cancel(color(black)("mol H"_2"O"))) × ("1 mol Ba(OH)"_2)/(2 color(red)(cancel(color(black)("mol H"_2"O")))) = "2.75 mol Ba(OH)"_2`

Step 3. Calculate the volume of `"Ba(OH)"_2`

`"Volume of Ba(OH)"_2 = 2.75 color(red)(cancel(color(black)("mol Ba(OH)"_2))) × ("1 L Ba(OH)"_2)/(0.125color(red)(cancel(color(black)("mol Ba(OH)"_2)))) = "22 L Ba(OH)"_2`