Household bleach is frequently used to disinfect surfaces and whiten fabrics. Understanding its chemical properties, particularly its pH level, is important for effective and safe use. The pH scale is a fundamental chemical measurement that indicates how acidic or alkaline a substance is, directly influencing its behavior and interactions.
What is pH?
The pH scale is a numerical system from 0 to 14, used to classify substances based on their acidity or alkalinity. A pH value of 7 indicates neutrality, much like pure water. Values below 7 signify increasing acidity, with 0 being the most acidic. For instance, lemon juice typically has a pH around 2.
Values above 7 denote increasing alkalinity, also known as basicity, with 14 representing the most alkaline. Each step on the pH scale represents a tenfold change in acidity or alkalinity, meaning a substance with a pH of 8 is ten times more alkaline than one with a pH of 7. Common household examples include baking soda, which is mildly alkaline.
The pH Level of Common Bleach
Common household chlorine bleach, which is primarily a solution of sodium hypochlorite, is highly alkaline. Its pH typically falls within a range of 11 to 13. When sodium hypochlorite dissolves in water, it undergoes a chemical reaction that produces hydroxide ions. These hydroxide ions are responsible for the solution’s high pH and its characteristic caustic properties. Maintaining this alkaline environment is important for the stability and effectiveness of the active ingredient, sodium hypochlorite.
How Bleach’s pH Affects Its Properties
The high pH of bleach plays a significant role in its effectiveness as a cleaning and disinfecting agent. Its alkalinity helps break down organic matter like dirt, grease, and oils. Furthermore, the high pH contributes to its ability to kill microorganisms by denaturing proteins and disrupting the cellular structures of bacteria, viruses, and fungi. This action involves attacking the lipids in cell walls and destroying essential enzymes within the microbes.
However, this strong alkalinity also makes bleach corrosive. It can cause irritation or chemical burns upon contact with skin and eyes. The oxidizing nature of sodium hypochlorite can also lead to the corrosion of metals, causing damage.
The pH also influences bleach’s stability and shelf life. While an alkaline pH (typically 11-12) helps stabilize the solution, factors like heat, light, and the presence of metal ions or impurities can accelerate its decomposition. Bleach solutions can lose their effectiveness over time, especially when diluted, often becoming less potent after 24 hours.
Safe Interaction with High pH Bleach
Given bleach’s high pH and corrosive nature, safe handling, storage, and usage are important. When working with bleach, wear protective gear, such as rubber gloves and eye protection. Ensure adequate ventilation by opening windows or using fans to disperse irritating vapors.
Proper storage is also crucial; bleach should be kept in a cool, dry, and dark place, away from direct sunlight and heat, and always out of reach of children and pets. Never mix bleach with other cleaning products, especially those containing ammonia or acids.
Mixing bleach with ammonia can produce toxic chloramine gases, leading to symptoms such as coughing, nausea, shortness of breath, and irritation to the eyes, nose, and throat. Similarly, combining bleach with acids releases highly toxic chlorine gas, which can cause respiratory issues and eye irritation.
In case of accidental exposure, immediate first aid is necessary.
- If bleach contacts the skin, rinse the affected area with plenty of water for 15 to 20 minutes and remove any contaminated clothing, then gently wash with mild soap and water.
- For eye contact, hold the eye open and rinse gently with water for 15 to 20 minutes, removing contact lenses if present, and seek immediate medical attention.
- If bleach fumes are inhaled, move the person to fresh air and contact poison control or emergency services if breathing is affected.
- Ingesting bleach is a medical emergency, and poison control or emergency services should be called immediately; do not induce vomiting or give anything by mouth to an unconscious person.