I think you mean 0.025 M and this is the answer: if your final volume is for example 100 ml, you have to take 208 microliters of stock solution and bring it to 100ml with water.
yes, this is basic biochemistry! sad sigma company and others no longer states the biophysical/biochemical data on their flasks....I have contacted sigma and they answer that there is no free space on the label to write the data....beurk :-)
Firstly, calculate the molar using the following equation M = 10XdensityXpercentage(37 in your case)/Molecular Weight. Then calculate the required molarity by dilution.
Simply put. 37% SOLUTION means it is containing 37g in 1000ml which in turn means 1 Molar solution app. Hence take 25ml (0,925g) and dilute further to 1000ml to get 0.025molar solution.
Chinnapillai, are we talking about approximate concentration here or having a more accurate concentration? Do you know the density of 37% HCl is 1.19g/l and not exactly the same as water? So 2.5g of HCl should give a volume of 2.5/1.19=2.1ml. I also wonder why you assume 37% HCl should have a molar concentration of 1.00M. Concentration of stock acid solutions should be given on the container label and I pressume 37% HCl has a Conc of ~12.0M or can be calculated using the simple equation; [(% x d) / MW] x 10 = Molarity .
Dinesh, your question should be asking about how much of 37% HCl is need to prepare a certain volume and concentration (Molar not moles because Molar means moles per litre) of solution. If however you meant to say 0.025M and assuming you want to prepare 1L solution then the volume of 37% HCl needed should be=(1000 X 0.025X 36.5)/(37X1.19X10)=2.07 mL diluted to 1 L using DI water.
Dear Sir, the following method is quoted from the BP which more usefull in daily routine practice and saving time for calculations. The idea is to multiply the factor below (85) by the deisred molarity concentration which will give the volume requirred to be taken from the concentrated HCl acid and diluted up to 1000 mL.
Hydrochloric Acid HCl = 36.46
Where no molarity is indicated use analytical reagent grade of commerce with a relative density of about 1.18, containing not less than 35% w/w and not more than 38% w/w of HCl and about 11.5M in strength.
Solutions of molarity xM should be prepared by diluting 85x ml of hydrochloric acid to 1000 ml with water .
First check the specific gravity of the commercial stock. It is probably 1.175. Since the gravity of water is approx 1; this value equates to approx 1.175 gms/ml i.e. 1175 gms/lit
Then calculate the molarity of the commercial solution - Molarity = moles/lit = Mass (gms)/Mol wt/Vol (lit) i.e. 1175/36.5 = 32 M
Thus the commercial stock is supplied at 32 M
A 37% solution would have 37 ml diluted to 100 ml in water. Thus it would be 0.37 fold dilution and therefore 32 X 0.37 = 11.8 M
Now if you want a 0.025 M solution (molar not moles) in a volume of say 100 ml, use the following formula, N1V1=N2V2
0.025 M X 100 ml = 11.8 M X (x) ml
Thus x = 0.025X100/11.8 = 0.211 ml
Take 0.211 ml of your 37% HCl solution and make up to 100 ml with water
Since the concentrated HCl is quite inconvenient and hard to handle it is just impossible to take a small volume properly, this way the direct one-step dilution will not recommended and surely would not result in a correct concentration. The most reliable method is to make a 10x dilution first, then to determine the exact concentration of this stock solution by titrimetry in order calculate the proper volumes for a further 2nd step dilution to approach the correct final result.