DETERGENTS

14.1 DETERGENTSSLIDES BY MUHAMMAD FIRDAUSPRESENTED BY RADIOACTIVEWhat is detergent?Detergents are salts produced from the neutralisation reaction between an alkyl hydrogen with an alkali.An example of a detergent is sodium lauryl sulphate.The general formula of a detergent is RSO3O-NA+ if sodium hydroxide is used.

PREPARATION OF DETERGENT

The cleansing action of detergentsDetergent dissolve in water to form sodium ions, Na+ and detergent ions.In water, the sodium salt of a detergent will dissociate to produce sodium ions, Na+, and anions of detergent.

The structure of the detergent ion can be represented by the structure in this diagram

5Detergents work to reduce surface tension of water so that water can wet the surface of the material better

Cleansing action of detergents

Comparison of the effectiveness of the cleansing action of soaps and detergentsSoaps cannot be used in hard waterThe magnesium and calcium ions in hard water react with soap to form scum which is insoluble in water.Scum is the precipitate formed when soap reacts with hard water.RCOONA(s) RCOO-(aq) + Na+(aq)

RCOO-(aq) + Ca2+(aq) (RCOO)2Ca(s)Soap calcium ion scumRCOO- (aq) + Mg2+(aq) (RCOO)2Mg(s)Soap magnesium ion scum

Soap does not produce foam in hard water and the soap is wasted.Detergents can be used in hard waterDetergent does not form scum in hard waterCalcium or magnesium salt of detergent dissociates easily in water. [R-O-SO3-]2Ca2+ 2R-O-SO3- + Ca2+ [R-O-SO3-]2Mg2+ 2R-O-SO3- + Mg2+

Detergents form bubbles in hard water.Solid soapDissolved soapSoap is non-pollution because soap is biodegradable. The use of detergents pollutes the environment because it is non-bio-degradableAn example of hard water is sea water and examples of soft water are river water and well water. Soft water does not contain magnesium ions, Mg2+ and calcium ions, Ca2+Additives in DetergentsDetergent additiveFunctionBiological enzymesAccelerate the process of cleaning by breaking down dirt such as food, blood or oilBleaching agentsExample: sodium perborate and sodium hypochloriteBleaching agents remove coloured stains on white fabrics by oxidising the dirt (but do not bleach the dyes on the coloured fabrics).Fluorescent materialsFluorescent materials absorbs ultraviolet radiation from the sun and emits blue light causing the cloth to appear brighter.Drying agentsExample: anhydrous sodium sulphate and sodium silicateMaintain the detergent powder in dry conditions.StabilisersExample: ethanolamidePrevents excessive foam production, especially when using washing machines.THANK YOU!