SPM Chemistry Form 5 Notes – Chemicals for Consumers (Part 4)

by BerryBerryTeacher

in Berry Reference (Notes)

As you would have known in the previous post that soaps and detergent do have their differences. This post, Part 4 in the series of notes on Chemicals for Consumers by Berry Berry Easy for SPM Form 5 Chemistry is about the effectiveness of the cleansing actions of the two products in different conditions. The conditions includes hard water, soft water, acidic water and its general biodegrability in the environment.

Giving focus to detergents, additives in detergents are also discussed in this post. There are a variety of additives to be added in detergents. Among common detergent additives are optical brighteners to improve the vibrant colours of your clothes which act by converting invisible UV lights into visible lights, in turn allowing additional light reflections. Another common detergent additives is bleach. Bleaching works through the whitening of fabric from the destruction of dirt and colours. A list of other common detergent additives are listed in the table below.

[Tips: For the detergent additives, it should be noted that a combination of additives are added to detergents rather than just a single type of additives. For example, a detergent will probabloy have virtually all the additives mentioned below even if the advertising focus is on the whitening or optical brightening aspect. More importantly, soaps can also have additives although it is not mentioned in this sub-chapter. The best example of additives in soap is fragrance, where your soap may have floral fragrance.]

SPM Chemistry Form 5 Notes – Chemicals for Consumers (Part 4)

Natural Olive Oil and Palm Oil Soap

The effectiveness of the cleansing action of soap and detergent

Condition Soap Detergent
Hard water (contain calcium & magnesium ion) Form an insoluble precipitate  = soap scum (formation of soap scum causes wastage of soap) Detergent is effective cleaner. Form soluble substances = calcium or magnesium salts (do not form scum)
Soft water (do not contain calcium & magnesium ion) Soap is effective cleaner. Detergent is effective cleaner.
Acidic water (contain hydrogen ion) Form insoluble long-chain fatty acids (reduces the amount of soap used for cleaning) Detergent is effective cleaner. Form soluble substances (Do not form scum)
Environment Soap is biodegradable Soap is non-biodegradable

Additives in detergent

Additives Function Example
Biological enzyme Remove protein stains Amylase, lipase & protease
Foam control agent Control foaming in detergent Silicones
Builder Enhance the surfactant efficiency Sodium phosphate
Filler Make the solid detergent dry and enable the liquid detergent to be poured easily Sodium silicate
Fragrance Add fragrance -
Optical brightener Add brightness by convert UV radiation to blue light and whiteness Fluorescent dye
Stabilising agent Lower the production of foam Silicones
Suspension agent Prevent the dirt particles removed from redepositing onto cleaned fabrics Sodium carboxymethylcellulose
Whitening agent Bleach stains Sodium hypochlorite

The next post, Part 5 in the series of notes on Chemicals for Consumers for Form 5 SPM Chemistry by Berry Berry Easy will be on food additives with the focus on preservatives.

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