Strong and Weak Solutions

C

Chris24

Hi,

I'm a new science technician, and I was wondering, with regard to osmosis practicals, when preparing a weak sugar solution, concentrated sugar solution, or strong salt solution, what precise amounts give the best results?
 
JeanS

JeanS

Chris24 said:
Hi,

I'm a new science technician, and I was wondering, with regard to osmosis practicals, when preparing a weak sugar solution, concentrated sugar solution, or strong salt solution, what precise amounts give the best results?
Click to expand...
we use 0, 0.2, 0.4, 0.6, o.8 and 1M sucrose solutions
 
Stokes1

Stokes1

We used to do the same as JeanS, but now we use 0, 0.1, 0.2, 0.3, 0.4 and 0.5M sucrose solutions. Using anything stronger seemed a waste, since potatoes are isotonic around the 0.2M mark.
 
Paul

Paul

Stokes1 said:
We used to do the same as JeanS, but now we use 0, 0.1, 0.2, 0.3, 0.4 and 0.5M sucrose solutions. Using anything stronger seemed a waste, since potatoes are isotonic around the 0.2M mark.
Click to expand...
edexcel it want in % starting over 1M :(
 
A

Andrew Symonds

I tend to go with sodium chloride for this, a 6% w/v solution is close enough to 1M, this is diluted to provide solutions of 1.2%, 2.4%, 3.6% and 4.8%, if you include water you get six sets of data for mass or dimensional change. Potato is supplied already chipped, carrot batons work well too.
 
St Caths Crew

St Caths Crew

We go for 0.25M, 0.5M and 1.0M sugar solution.

We give out cork borers and white tiles so they can cut there own potato.

Results are good if they follow the instructions
 
Paul

Paul

Purple Cat said:
We use 0.0M, 0.5M, 1.0M salt solutions. Cheaper, and you can guarantee all of the solid dissolving.

100% sugar solns would be molasses
Click to expand...
approx. 550 g/dm3 sucrose is what edexcel want in the req prac instructions. (about 1.6M you need a kettle to dissolve it.)
 
kaj

kaj

I do 0.2, 0.4, 0.6 and 1M salt solutions. Cheaper and not as sticky when it's knocked over. When they just want strong and weak solutions I do one spoonful of salt and either 3,4 or 5 spoonfuls, depending on how I'm feeling and how much salt we have.
 
Alex C

Alex C

Salt here too. Cheaper, less sticky and messy so easier clear up plus dissolves more easily so easier prep.
 
Peter Sigsworth

Peter Sigsworth

COMMITTEE
Paul said:
approx. 550 g/dm3 sucrose is what edexcel want in the req prac instructions. (about 1.6M you need a kettle to dissolve it.)
Click to expand...
This is their receipe:

Sucrose is made up as follows:
100% is 550g/l. The others are dilutions of the 100% (so make up 1l to give you 400ml of 100% and 500ml of the rest):
40% = 200ml made up to 500ml with distilled water
80% = 400ml made up to 500ml with distilled water
0% is distilled water

It works well
 
Paul

Paul

Peter Sigsworth said:
This is their receipe:

Sucrose is made up as follows:
100% is 550g/l. The others are dilutions of the 100% (so make up 1l to give you 400ml of 100% and 500ml of the rest):
40% = 200ml made up to 500ml with distilled water
80% = 400ml made up to 500ml with distilled water
0% is distilled water

It works well
Click to expand...
I do it by weight now.
 
P

Puds

TDM said:
Salt here too.... 0.2 0.4 0.6 0.8 1.0M

I have the amount needed to make a litre of each molar printed on the lid of the salt container to save me keep working it out... ;)
Click to expand...
Yup good idea, I've done this with quite a few chemicals too, saves brain work on a bad day!
 
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