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When cleaning household surfaces, understanding the chemistry of your products can inform safer and more effective use. Bleach, for instance, is a powerful disinfectant with a highly alkaline composition that can neutralize acids, dissolve fats, and eliminate germs.
The pH scale, ranging from 0 to 14, quantifies how acidic or alkaline a solution is. A pH of 7 is neutral; values below 7 indicate acidity, while those above 7 signal basicity. Because the scale is logarithmic, each whole‑number step represents a tenfold change in hydrogen‑ion concentration.
Litmus paper, derived from lichens, offers a simple way to distinguish acids from bases. Red litmus stays red in acidic solutions (pH < 4.5) and turns blue in basic environments (pH > 8.3). Blue litmus remains blue in basic solutions and turns red under acidic conditions. Solutions between pH 4.5 and 8.3 leave litmus unchanged.
For a more precise estimate of pH, universal indicator paper combines several dyes—methyl red, phenolphthalein, bromothymol blue, among others—creating a rainbow of colors that correlate with specific pH ranges. Strong acids turn the paper red, strong bases turn it violet, and neutral solutions appear green.
Place a drop of the solution on a strip of red or blue litmus paper, or on universal indicator paper. Observe the color change and compare it to the reference chart provided by the manufacturer. The resulting shade will indicate whether the solution is acidic or alkaline and approximate its pH value.
Household bleach (sodium hypochlorite, NaClO) is a bright yellow or greenish liquid with a pH around 11, firmly in the alkaline range. When applied to red litmus paper, bleach turns the paper blue, while blue litmus remains unchanged. On universal indicator paper, bleach produces a violet hue, confirming its strong basicity.
Because concentrated bleach can irritate skin and eyes, always wear protective gloves and eyewear, and work in a well‑ventilated area to avoid inhaling fumes.
