Q92E

Question

What mass of Ca(OH)2 will react with 25.0 g of propionic acid to form the preservative calcium propionate according to the equation?



Step-by-Step Solution

Verified
Answer

The mass of calcium hydroxide that will react with 25.0 g of propionic acid is 31.524 g

1Step 1: Moles of calcium hydroxide

According to the question, it is given that 

The mass of propionic acid is 25.0 g and the molecular mass is 88 ml.\({\rm{Moles  =   }}\frac{{{\rm{Mass}}}}{{{\rm{Molar mass}}}}\)

\({\rm{Moles  =  }}\frac{{25}}{{88}}{\rm{  =   0}}{\rm{.284 moles}}\)

When calcium hydroxide reacts with propionic acid, the reaction is given by:

\({\rm{3Ca(OH}}{{\rm{)}}_2}{\rm{  +   2}}{{\rm{C}}_3}{{\rm{H}}_7}{\rm{COOH }} \to {\rm{ C}}{{\rm{a}}_3}{{\rm{(}}{{\rm{C}}_3}{{\rm{H}}_7}{\rm{COO)}}_2}{\rm{  +   6}}{{\rm{H}}_2}{\rm{O}}\)

As 3 mole of calcium hydroxide reacts with 2 moles of propionic acid then 0.284 moles of propionic acid will react with \(\frac{3}{2}{\rm{ }} \times {\rm{ 0}}{\rm{.284  =   0}}{\rm{.426 moles}}\)

2Step 2: Mass of calcium hydroxide

According to the mole concept, the number of moles is the ratio of the mass of solute and the molecular mass of the solute. It is given that the number of moles of calcium hydroxide is 0.426 moles and molecular mass is 74 g/mol. 

Thus, the mass of calcium hydroxide will be:

\(\begin{array}{l}{\rm{Mass}} = {\rm{Moles \times Molecular}}\,{\rm{Mass}}\\{\rm{Mass   =  0}}{\rm{.426 }} \times {\rm{ 74  =   31}}{\rm{.524 g}}\end{array}\)