problem 1:

A solution needs 250 ml of a 7.5% (w/v) solution of tri sodium citrate. The only citrate you encompass available is the dehydrate, C₆H₅O7Na₃. 2H20 through a formula weight of 294.1.How much would you encompass to make up this solution?

problem 2:

A citrate buffer should be made up to a final concentration of 50mM. You require making up 2L. You have to stock solutions from which to make this buffer; 0.1 M citric acid (C₆H₈O₇) and 0.1 M Sodium citrate (C₆H₅O₇Na₃). You require adding twice as much of the acid form than the base form to accomplish the desired pH. Illustrate how will you make up this solution?

problem 3:

To isolate RNA you frequently use a protein denaturant solution of guanidinum salts. Such chaotropic solutions denature through disrupting H-bonding. The solution also contains a reducing agent to denature the disulfide bonds. The final composition of the solution is: 4 guanidine isthiocyanate (GITC), 25mM sodium citrate, pH 7.0, 0.5% (w/v) SDS, 100mM β-mercaptoethanol. You have guanidine isothiocyanate powder (mol.Wt.118.16),1 M NaCitrate, pH 7.0, powder SDS and b-mercaptoethanol (density 1.12 g/mL, mol. Wt.78.1). How would you build up 100 mL of this solution?