How many grams of NaOH can be obtained by treating 1kg of Na2CO3 with Ca(OH)2?

Question

Caustic soda, NaOH, is often prepared commercially by the reaction of Na2CO3 with slaked lime, Ca(OH)2. How many grams of NaOH can be obtained by treating 1kg of Na2CO3 with Ca(OH)2?

Answer 1

For this we need the atomic weights of Na, C, O and H:

Na=22.9893, C=12.0096, O=15.9994, H=1.008.

The molecular weight of Na₂CO₃ is 2×22.9893+12.0096+3×15.9994=105.9864.

In the reaction two molecules of NaOH are produced, and the atomic weight of the product is:

2(22.9893+15.9994+1.008)=79.9934.

The weight in grams of Na₂CO₃ is 1000. If the constant N relates the atomic weight to the weight in grams we have N=1000/105.9864=x/79.9934 where x is the weight of NaOH. So x=1000×79.9934/105.9864=754.75g approx.