It is your first day in a new summer job and in order to collect field samples y

Question

It is your first day in a new summer job and in order to collect field samples you need to prepare Saline solution. 2. a) You decide to prepare a 5M Nacl (58.5 g.mol) stock solution which you will be able to use throughout the summer. You decide on 250ml. How much NaCI should you weigh out? b) Now you need to dilute your 5M NaCI to a working concentration of 140mM for the Saline, you need 100mL for your field trip, how much of the 5M NaCl should you add? c) How would you sterilize your saline before you collect the samples?

Explanation / Answer

a)

M = mol/V

mol = MV = 5*0.25 = 1.25 mol of NaCl

mass = mol*MW

mass = 1.25*55.8

mass of NaCl = 69.75 g

b)

dilutoin for:

M1V1 = M2V2

5M * V = (140*10^-3) * 100 mL

V =  (140*10^-3) * 100/5

V = 2.8 mL

c)

most likely we apply the "dry heat" method

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