Very small particles of dirt and lie in the 0.1mm spaces between threads in a sh
ID: 1843759 • Letter: V
Question
Very small particles of dirt and lie in the 0.1mm spaces between threads in a shirt garment causing a grass stain. Marketing materials for stain remover like SHOUT suggest that SHOUT will ‘lift stains out’ but it would be more physically accurate to say instead that SHOUT ‘lets the water in.’ Fig. 1 shows how temperature effects surface tension. Estimate differences in cleaning efficacy using assumptions of how effective water of different temperatures (e.g. hot vs cold water) cleans to support your argument. Based on your premises, does stain remover increase or decrease water’s surface tension?
Explanation / Answer
The surface tension of water decreases with increase in temperature. The chemicals in the detergents called surfactants which consists of two ends. One end is of the molecule is attracted to water and the other end is attracted to the dirt. So by adding hot water, the surface tension reduces thereby making the clothes wet. Hence, under the water conditions, the detergent is more efficient.
Thus, the surface tension of water should be lowered in order to remove the dirt easily. Hence, the detergent decreases the surface tension.
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