Chemistry Questions related to experiments

7woohoo7

Just have a few queries and I can't find the answers anywhere, so here goes:

If pure samples of 2 different substances with the same melting pts are mixed, is the melting pt lower, the same, or higher?
I assume it's the same?

For the extraction of clove oil from cloves, what other natural product could be used?
Caffeine (coffee beans)?

How would one find the molecular mass of a non-volatile liquid e.g glycerol?
Mass spec?

What change is observed in the appearance of calcium dicarbide when water is added to it?
I know ethyne is produced but what change is there in the appearance?

How would one find the melting pt of an ionic substance?

In recrystallisation of impure benzoic acid, what do you do if too much solvent is added?

What is exactly meant by '20 volumes' or '100 volumes'?
Something like 20 volumes of water to one volume of the substance?

What is observed when a test tube containing cyclohexane and bromine is held near a source of UV light for a few minutes? Why?
A chain reaction occurs and?

Why is distillation neccessary to produce whiskey but not wine?

Why are many esters volatile?

By what name was ethanal formerly known?
Acetaldehyde?

mawk

7woohoo7 wrote:

If pure samples of 2 different substances with the same melting pts are mixed, is the melting pt lower, the same, or higher?
I assume it's the same?


Why is distillation neccessary to produce whiskey but not wine?

eh chemestry is not my strong suite but, i can tell you that,1: the melting point Should differ to the origional constituants, it would vary alloy to alloy though

and,2: distillation is used because sugars wont ferment above a certain % which im not going to guess without a cite but its well below the 40+% of whiskey

Creature

7woohoo7 wrote:

For the extraction of clove oil from cloves, what other natural product could be used?
Caffeine (coffee beans)?

Using steam distillation? I would've said eucalyptus oil.

7woohoo7 wrote:

How would one find the molecular mass of a non-volatile liquid e.g glycerol?
Mass spec?

Yup.

7woohoo7 wrote:

In recrystallisation of impure benzoic acid, what do you do if too much solvent is added?

I suppose you'd just let some of the solvet vap off. Thats what I'd do anyway.

7woohoo7 wrote:

Why are many esters volatile?

I would imagine this is because the ester molecules lack hydrogen bond donating sites and the molecules can't H bond with each other.

7woohoo7 wrote:

By what name was ethanal formerly known?
Acetaldehyde?

Yup.

ArthurDent

7woohoo7 wrote:

If pure samples of 2 different substances with the same melting pts are mixed, is the melting pt lower, the same, or higher?
I assume it's the same? afair mixing causes elevation of melting point and depression of freezing point




Why is distillation neccessary to produce whiskey but not wine?
Looking to concentrate the alcohol

hope this helps

Darando

7woohoo7 wrote:

What change is observed in the appearance of calcium dicarbide when water is added to it?
I know ethyne is produced but what change is there in the appearance?

Goes cloudy (milky) from the calcium hydroxide formed.

7woohoo7 wrote:

In recrystallisation of impure benzoic acid, what do you do if too much solvent is added?

remove the solvent - evaporate - heat or similar.