A 50.0 mL sample of HCl required 25.81 mL of 0.1250 M KOH for neutralization. What is the molarity of the acid?

0.065M

Explanation:

The reaction expression is given as:

         HCl   +   KOH  →  KCl + H₂O

Given parameters:

Volume of KOH  = 25.81mL  = 0.02581L

Molarity of KOH = 0.125M

Volume of HCl  = 50mL  = 0.05L

Unknown:

Molarity of the acid  = ?

Solution:

To find the molarity of the acid, HCl, let us use the mole concept.

  First, find the number of moles of the base, KOH;

Number of moles of KOH = molarity of KOH x volume of KOH

   Number of moles of KOH  = 0.125 x 0.0258 = 0.003225mol

From the balanced reaction equation:

   1 mole of KOH reacted with 1 mole of HCl

   0.003225mol of KOH will react with 0.003255mole of HCl

Molarity of HCl  =

Molarity of HCl  =   = 0.065M

The mass of carbon dioxide formed in the reaction is 269 grams.

Explanation:

Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.

This also means that total mass on the reactant side must be equal to the total mass on the product side.

The chemical equation for the decomposition of calcium carbonate follows:

Let the mass of carbon dioxide be 'x' grams

We are given:

Mass of calcium carbonate = 612 grams

Mass of CaO = 343 grams

Total mass on reactant side = 612 g

Total mass on product side = [343 + x] g

So, by applying law of conservation of mass, we get:

Hence, the mass of carbon dioxide formed in the reaction is 269 grams.