Mixing Bleach and Vinegar

Why You Shouldn't Mix Bleach and Vinegar and Why People Do It Anyway

Mixing bleach and vinegar releases chlorine gas. This yellowish gas is harmful if inhaled, as well as irritating to your eyes, nose, and throat.
Pamela Moore, Getty Images

Mixing bleach and vinegar is a bad idea. Toxic chlorine gas is released, which essentially serves as a way to wage chemical warfare on one's self. Many people mix bleach and vinegar, knowing it's dangerous, but either underestimate the risk or else hope for increased cleaning power. Here's what you should know about mixing bleach and vinegar, before trying it.

Why People Mix Bleach and Vinegar

If mixing bleach and vinegar releases toxic chlorine gas, then why do people do it?

There are two answers to this question. The first answer is that vinegar lowers the pH of bleach, making it a better disinfectant. The second answer to 'why people mix bleach and vinegar' is that people don't recognize how dangerous it is or how quickly it reacts. They hear mixing the chemicals makes them better cleaners and disinfectants, but don't realize the cleaning boost isn't going to make enough of a difference to justify the considerable health hazard.

What Happens When Bleach and Vinegar Are Mixed

Chlorine bleach contains sodium hypochlorite or NaOCl. Because bleach is sodium hypochlorite in water, the sodium hypochlorite in bleach actually exists as hypochlorous acid:

NaOCl + H2O ↔ HOCl + Na+ + OH-

Hypochlorous acid is a strong oxidizer. This is what makes it so good at bleaching and disinfection. If you mix bleach with an acid, chlorine gas will be produced. For example, mixing bleach with toilet bowl cleaner, which contains hydrochloric acid, yields chlorine gas:

HOCl + HCl ↔ H2O + Cl2

Although pure chlorine gas is greenish-yellow, gas produced by mixing chemicals is diluted in air. It's invisible, so the only way to know about it is by the smell and negative effects. Chlorine gas attacks mucous membranes, such as eyes, throat, and lungs and can be deadly. Mixing bleach with another acid, such as the acetic acid found in vinegar, yields essentially the same result:

2HOCl + 2HAc ↔ Cl2 + 2H2O + 2Ac- (Ac : CH3COO)

There is an equilibrium between the chlorine species that is influenced by pH. When the pH is lowered, as by adding toilet bowl cleaner or vinegar, the ratio of chlorine gas in increased. When the pH is raised, the ratio of hypochlorite ion is increased. Hypochlorite ion is a less efficient oxidizer than hypochlorous acid, so some people will intentionally lower the pH of bleach to increase the oxidizing power of the chemical, even though chlorine gas is produced as a result.

What You Should Do Instead

Don't poison yourself! Rather than increasing the activity of the bleach by adding vinegar to it, it's safer and more effective to simply purchase fresh bleach. Chlorine bleach has a shelf life, so it loses power over time. This is particularly true if the container of bleach has been stored for several months. It's far safer to use fresh bleach than to risk poisoning by mixing bleach with another chemical. It is fine to use bleach and vinegar separately for cleaning as long as the surface is rinsed between products.