Tutor profile: Viktoriia C.
Subject: Organic Chemistry
Why is it easier to wash grease off metalic pan rather than off plastic vessel?
As we know, organic matter attracts organic matter and inorganic attracts inorganic. Fats are glycerides, formed from fatty acids, meaning that their molecudes have long organic chains, which do not stick to inorganic metal surface but are very fond of organic plastic materials. They tend to cling to them by rather strong physical Van der Waals forces. This really complicates the washing process.
Subject: Inorganic Chemistry
Why do we prefer to add sulfuric acid to water when mixing them rather than vise versa?
Sulfuric acid is known to vigorously react with water ( i.e. it is highly hydroscopic). The thing is that when one molecule of this acid collides with water molecules it forms hydrates (H2SO4*2H2O). As we know, when chemical bond is formed, energy is released. In this case large amount of energy is released, i.e. the reaction is highly exothermic. So in order to prevent accident, we pour acid to water, because then it is added in small enough portions and the reaction won't be as vigorous.
Subject: Basic Chemistry
Whe are noble gases inert?
Atoms of each chemical element try to complete their outer electron shells by sharing electrons (in that case we call in covalent bond) or by giving/accepting them (i.e. ionic bond). But in the case of inert gases their atoms have complete outer electron shells hence they don't need to combine with other elements. Thus they exist in form of free atoms.
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