Having completed this lab, you should now be able to describe how to prepare sol

Question

Having completed this lab, you should now be able to describe how to prepare solutions For each of the scenarios below, perform the appropriate calculations and write a procedure for preparing each solution in a series of steps (as presented in this lab procedure), including the calculated amounts of reagents needed, as if you are instructing someone to prepare the solutions. Show your work for your calculations, paying close attention to significant figures. 5. Write a step-by-step experimental procedure to prepare 500 mL of 0.150 M NaNO3 in a 500 mL volumetric flask. Sodium nitrate (NaNO3) is a solid at room temperature Write a step-by-step experimental procedure to prepare 200 mL 0.20 M HNO3 from 16.0 M HNO3 (concentrated nitric acid) in a 200 mL volumetric flask. In your procedure, be clear regarding the tendency of concentrated acids to generate heat and boil or splash over the sides of a container when added to water; concentrated acid is always added to water rather than water to concentrated acid. a. b.

Explanation / Answer

a) Molarity of NaNO3 needed = 0.15 M

Volume of NaNO3 solution = 500 mL

Molarity expression is given by

M = (weight of solute/mol.wt of solute)(1000/V(ml))

Weight of NaNO3 =?

Mol. wt of NaNO3 = 85 g/mol

V = 500 mL

0.150 M = (wt./85)(1000/500)

Weight = 01.50*85*500/1000 = 6.375 gms

Thus, 6.375 g of solid NaNO3 has to be dissolved in water and make upto 500 mL

b) Dilution expression is given by

M1 V1 = M2 V2

M1 = Initial molarity = 16.0 M

V1 = volume =?

M2 = final molarity = 0.20 M

V2 = volume required = 200 mL

now, 16*V1 = 0.2*200

V1 = 0.2*200/16 = 2.5 mL

Thus, 2.5 mL of 16.0 M HNO3 solution is transferred into 200mL standard flask and make upto 200 mL

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