Question

Describe 3 everyday situations in which it would be useful to identify unknown substances and explain how you would identify these substances

Answer 1

Here are three everyday situations which it would be useful to identify unknown substances:
1. When you have two clear substances with no labels yet you are not sure which substance is water and which one is not and not knowing what this unknown chemical might do.
2. A stain on your clothes
3. When you are not feeling well and your sense of taste is not functioning well.
The ways that these can be identified is first, start by the appearance, for example the state, color, texture, etc. And secondly, use your sense of smell. This sense is also helpful in identifying whether the substance is something strong or not.

Answer 2

The three situations can be described as

a) If we have two white powders and wish to distinguish between the two : the combinations can be sugar / salt or sugar / baking soda or salt / baking soda

all are kitchen items so we can either taste them

or in case of baking soda we can add it in water and it will produce brisk effervescence.

b) IF we have to distinguish in a given set of two transparent liquids which appear to be water (example water and vinegar)

we can identify them with the taste

we can identify them based on pH (vinegar will be acidic)

c) We have to find adulteration in a given sample of food

like adulteration in milk

for example presence of soap in milk

We can add indicator like phenolphthalein which will bring a pink colour in milk if soap is present