Homework Help

What happens on heating a substance containing sodium carbonate in the presence of...

user profile pic

smf-samar | Student, College Freshman | eNotes Newbie

Posted August 4, 2011 at 11:18 PM via web

dislike 0 like

What happens on heating a substance containing sodium carbonate in the presence of water?

Will it give carbonic acid or caustic soda or carbonic acid?

2 Answers | Add Yours

user profile pic

giorgiana1976 | College Teacher | Valedictorian

Posted August 4, 2011 at 11:25 PM (Answer #3)

dislike -1 like

A substance containing sodium carbonate is sodium hydrogen carbonate. When this substance is heated, the products of reaction are sodium carbonate, carbon dioxide and water.

Heat + 2 NaHCO3 -> Na2CO3 + H2O(vapour) + CO(gas)

The more sodium hydrogen carbonate is heated, the less weight will have because water within evaporates.

Top Answer

user profile pic

pacorz | High School Teacher | (Level 3) Educator

Posted August 5, 2011 at 12:05 AM (Answer #4)

dislike -2 like

The correct answer to your question is both carbonic acid and caustic soda will be produced in the course of the reaction. This reaction proceeds as a two step process. In the first step we have this occurring:

NaCO3 + H2O -> H2CO3 + NaOH

Here, a double replacement reaction occurs in which hydrogen replaces sodium, resulting in the formation of both NaOH, also know as caustic soda or lye, and H2CO3, which is carbonic acid.

However carbonic acid is a weak acid, and will dissociate in the presence of the base into water and carbon dioxide. The full equation looks like this:

NaCO3 + H2O -> H2CO3 + NaOH -> H2O + CO2 + NaOH

So when the reaction is completed, you will be left with three products: Water, carbon dioxide, and sodium hydroxide. If the reaction is done in an open container, the carbon dioxide will bubble off, and the result will be a caustic soda solution.

 

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes