How Soap Cleans
Written by Studio AM.
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Water alone does not wash away oil. Try it. Rub a little cooking oil on your hands and hold them under the tap. The water runs off, and the oil stays. Water and oil do not mix. Oil does not dissolve in water.
Soap solves this problem. Soap contains tiny molecules with two different ends. One end is attracted to water. The other end can attach to oil. When you wash, the oil-loving ends push into the drop of grease and hold on. The water-loving ends point out, away from the grease.
Now the drop of grease is wrapped in a ball. The outside of that ball loves water, so the water can finally carry it. You rinse, and the grease goes down the drain inside its little package. This is why rubbing matters. Rubbing breaks the grease into small drops, and soap needs small drops to wrap. Soap helps water remove grease that water alone would leave behind.
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Questions
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Question 1 of 4
What is the main point of the passage?
The answer is C: Soap works by wrapping grease so that water can carry it away.
Soap molecules have different ends that help surround grease, allowing water to carry it away.
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Question 2 of 4
According to the passage, why does rubbing matter?
The answer is A: It breaks the grease into small drops that soap can wrap.
Rubbing helps break grease into small drops that soap can surround.
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Question 3 of 4
The passage suggests that without soap, grease stays on your hands because
The answer is D: oil does not dissolve in water
The opening explains that oil does not dissolve in water. Soap helps water carry the grease away.
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Question 4 of 4
In this passage, "rinse" means
The answer is B: to wash something away with clean water
The sentence is "You rinse, and the grease goes down the drain." Something is being washed away by water, not scrubbed, dried, or soaked.
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