Why do we cry while cutting an onion?
In this video, students will learn why we cry while cutting onions, and will answer questions related to the different substances present in onions. Prior knowledge on structure and bonding, different graphic representations of molecules, the collision model, enzymes and isomers, is required.
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Below is a skeletal structural formula of propene sulfenic acid. What is the molecular formula of propene sulfenic acid?
$C_{2}H_{2}OS$
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$C_{3}H_{4}OS$
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$C_{3}H_{6}OS$
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$C_{2}H_{4}OS$
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Below is a skeletal structural formula of the tear-triggering substance made of propene sulfenic acid. With the help of the periodic table of electronegativity, choose the correct answers.
The tear-triggering substance is produced in onion from propene sulfenic acid by an enzyme.
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The tear-triggering substance is an isomer of propene sulfenic acid.
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At least one polar covalent bond exists between the molecules of the tear-triggering substance.
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Hydrogen bonds exist between the molecules of the tear-triggering substance.
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One of the methods to prevent tears while cutting onions is to cool the onion before cutting it: there are additional methods to prevent tears. Below are different methods and an explanation as to why they work. Choose the answers with the correct explanations.
Cooling the onion in a refrigerator or a freezer - the number of collisions between the molecules of the enzyme and the molecules of the propene sulfenic acid is reduced, and therefore the rate of formation of the tear-triggering substance is reduced.
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Rinsing the onion in water while cutting - some of the molecules of the tear-triggering substance are water-soluble, are washed away and do not reach the eyes.
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Heating up the onion in the microwave - the energy of the tear-triggering substance increases, and therefore the tear-triggering substance evaporates faster and reaches the eyes less.
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Wearing diving goggles - the tear-triggering substance is formed and is dispersed to the environment, but cannot reach the eyes.
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Why do we cry while cutting an onion? - An interactive video
Play VideoActivity Overview
questions related to the different substances present in onions. Prior knowledge on structure and bonding, different graphic representations of molecules, the collision model, enzymes and isomers, is required.
Graphic representation of molecules, Molecular substances, intermolecular bonds, isomers, hydrogen bonds, enzymes, reaction rate, collision model
Knowledge building
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