A) Write a step-by-step experimental procedure to prepare 250 mL of 0.150 M Na3P

Question

A) Write a step-by-step experimental procedure to prepare 250 mL of 0.150 M Na3PO4 in a 250 mL volumetric flask. Sodium phosphate (Na3PO4) is a solid at room temperature.

B) Write a step-by-step experimental procedure to prepare 500 mL 0.20 M HCl from 12.0 M HCl (concentrated hydrochloric acid) in a 500 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 water is added to them; concentrated acid is always added to water rather than water to concentrated acid.

Explanation / Answer

Answer:

(A) Given volume=250 mL=0.250 L (since 1L=1000mL)

Molarity of Na3PO4=0.15 M=0.15 mol/L

=> First we have to calculate moles and mass of Na3PO4.

Moles=molarity x volume=0.15 mol/L x 0.250 L

Moles=0.0375 mol.

Molar mass of Na3PO4=163.94 g/mol

Therefore mass of Na3PO4=moles x molar mass

Mass=0.0375 mol x 163.94 g/mol=6.15 g.

=> In second measure exactly 6.15 g of Na3PO4 and transferred in to 250 mL volumetric flask.

=> Add small amount of water and dissolve the Na3PO4.

=> After dissolving make up to the mark by using water (distilled water).

=> Then 250 mL of 0.15 M Na3PO4 solution is ready.

(B) Here we have to dilute 12M HCl to 0.2 M of 500 mL solution.

We can use M1V1 = M2V2

Given M1=12 M, V1=?, M2=0.2 M and V2=500 mL.

V1=M2V2/M1=(0.2 M x 500 mL)/(12 M)

V1=8.333 mL.

=> First step fill 500 mL of volumetric flask ith half of water.

=> Then add 8.333 mL of 12 M HCl in to it.

=> Dissolve and make up to the mark.

=> Then 500 mL of 0.2M HCl is ready.

Thanks and I hope you like it. Please let me know if you have any doubt.

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