When roughly equal amounts of sodium bicarbonate or bicarbonate of soda (BOS) and warm vinegar are mixed a characteristic fizzing is seen. As any year 7 (first year of secondary school) science text book explains, the fizz is one of the characteristics which tells us that a chemical reaction is occurring. The reaction represents a highly effective and affordable method for both effective preventative drain maintenance and for removing minor blockages. The reacting mixture should be poured straight into the drain.
Alternatively, pour the bicarbonate of soda into the pipe work and then follow up with the vinegar. Ideally, the reaction should be left to run for several hours and should be repeated as necessary and flushed through with boiling water. Additionally, for DIY drain cleaning using BOS and vinegar together reduces the need for chemical cleaners and for professional assistance.
Why does the reaction happen?
It all comes down to one of the principal thread which runs through the study of chemistry. Put simply BOS (NaHCO3) is an alkali and vinegar or acetic acid (HCH3COO), is a weak organic (carbon based) acid dissolved in water. In chemistry acids and alkalis always react in what are known as neutralisation reactions. Put simply hydrogen in its charged (ionic state) is transferred to the alkali creating new compounds in the process.
This particular reaction is a two-step process. The products of the reaction are carbon dioxide gas – CO2 – (which produces the fizzing and bubbling), water and dilute solution sodium acetate (C2H3NaO2). In chemical terms the BOS removes hydrogen atoms from the vinegar and when this occurs the BOS is converted to water and carbon dioxide. The bubbles of CO2 are denser than the surrounding air and so collect on internal surface of the drain aiding the removal of unwanted material.
Exchanging atoms
The reaction between the BOS and vinegar is a complex process and occurs because there is an exchange of atoms. The exchange happens due to the behaviour of the electrons which are farthest from the nucleus of each atom in the reacting substances.
Each molecule of BOS contains an atom of sodium, hydrogen and oxygen and a molecule of CO2 while acetic acid contains hydrogen and an acetate ion. An ion is any positively or negatively charged atom or molecule and the charge on the acetate ion is negative. When BOS and vinegar react together (and while the hydrogen is removed from the vinegar by the BOS), the hydrogen atom in the acetic acid combines with the hydrogen and oxygen in the BOS to form a molecule of water.
Simultaneously, the acetate ion in the vinegar chemically bonds with the sodium atom in the BOS forming the sodium acetate in solution. The CO2 itself does not react with any of the reagents, that is the vinegar and BOS. However, the chemical bonds which attached it to the BOS molecule are broken and so it is able to bubble off into the surrounding atmosphere.
The above reaction is one of many neutralisation reactions that have clear benefits and represent a clear alternative to chemical cleaners for low key applications.