chloroform water: i do not know understand this question at all what is asking for

[Habib]

If double strength chloroform water is not available, this can be prepared by
dilution of concentrated chloroform water. Using the information given for the
composition of the different chloroform solutions, calculate the composition of
a convenient quantity of double strength chloroform water, sufficient to satisfy
the formula requirements but also enabling simple, accurate measurement of
concentrated chloroform water (i.e. fractions of millilitres cannot be accurately
measured). And describe in detail the method of preparation of double
strength chloroform water from concentrated chloroform water.
[12 marks]
Concentrated chloroform water Double strength chloroform water
Chloroform BP 100 mL Chloroform BP 5 mL
Alcohol 90% BP 600 mL Water f.b.c. to 1000 mL
Water f.b.c. to 1000mL

Regards

[Nik]

Chloroform water BP (also known as Single Strength Chloroform water) contains chloroform BP 2.5ml made up to 1000ml with FBC water. Double strength chloroform water BP contains 5ml chloroform water BP made up to 1000ml with FBC water. This is how both preps used to be made. However as solubility of chloroform is about 1 in 200 making the double strength prep was difficult, which is now why concentrated chloroform water is used. Nowadays, both preps are made as follows:

Single strength - Conc chloroform water 2.5ml, FBC to 100ml
Double strength - Conc chloroform water 5ml, FBC to 100ml

[Habib]

But this is one past exam question
it worth 12 marks
I know what you just explain to me thanks for that
even though i know how to make but that is really simple method
i am just wondering why is it worth 12 marks?
is something extra they asking which i did not get it ?
regards

Chloroform water BP (also known as Single Strength Chloroform water) contains chloroform BP 2.5ml made up to 1000ml with FBC water. Double strength chloroform water BP contains 5ml chloroform water BP made up to 1000ml with FBC water. This is how both preps used to be made. However as solubility of chloroform is about 1 in 200 making the double strength prep was difficult, which is now why concentrated chloroform water is used. Nowadays, both preps are made as follows:

Single strength - Conc chloroform water 2.5ml, FBC to 100ml
Double strength - Conc chloroform water 5ml, FBC to 100ml

[johnep]

I have made many a litre of Chloroform water, very slow to dissolve and needs vigorous shaking every few minutes.
johnep

[Nik]

The question (an old one by the looks of it) is asking for the quantities of the ingredients required to make double strength chloroform water and also how to make it up. To make up the conc chloroform water to use in the formula, you need to use the other ingredients. These are chloroform water BP, alcohol 90% BP and FBC water, which you have mentioned in your original post. The formula to make this first of all should be available in the BP. Once you make the conc chloroform water, you follow the formula I've written in my previous post to make double strength. Highly unlikely they'll ask you the formulas in the exam, but this does provide a bit of the background to the use of chloroform waters. If you can't remember anything else, at least learn the different dilutions needed to make the single and double strengths. If you know this you can answer any chloroform water question.

[Nik]

Absolutely johnep which is where the newer conc chloroform came into play, as the chloroform would dissolve in the alcohol then the water would be added.

[johnep]

We did have Conc Chlorof available in my day. My dispenser showed me how to use it in preparing mist aspirin to avoid having to use a pestle and mortar. When I got to Uni demonstrated method there along with similar method in preparing Mist Lobelia and Stramonium.
They were suitably impressed.
johnep

[Asterix]

Chloroform water BP (also known as Single Strength Chloroform water) contains chloroform BP 2.5ml made up to 1000ml with FBC water. Double strength chloroform water BP contains 5ml chloroform water BP made up to 1000ml with FBC water. This is how both preps used to be made. However as solubility of chloroform is about 1 in 200 making the double strength prep was difficult, which is now why concentrated chloroform water is used. Nowadays, both preps are made as follows:

Single strength - Conc chloroform water 2.5ml, FBC to 100ml
Double strength - Conc chloroform water 5ml, FBC to 100ml

whats fbc?

[Nik]

Freshly boiled and cooled water

[Ushio78]

We did have Conc Chlorof available in my day. My dispenser showed me how to use it in preparing mist aspirin to avoid having to use a pestle and mortar. When I got to Uni demonstrated method there along with similar method in preparing Mist Lobelia and Stramonium.
They were suitably impressed.
johnep

As I'm not familiar at all with the procedure, could I ask you to expand a little further on it? I've already tried an online search with no result.

Matt