Preparation of solutions

CHEMISTRY

1. Preparation of Solutions Experiment #2 CHEM 2 (General & Inorganic Chemistry)

2. Objective: To prepare solutions of various concentrations.

3. Materials: 100 ml graduated cylinder 100 ml volumetric flask 500 ml beaker watch glass stirring rod 2 pipette 2 aspirator spatula 5 empty reagent bottles

4. Chemicals (REAGENTs) : concentrated HNO3

5. Chemicals (REAGENTs) : concentrated H2SO4

6. Chemicals (REAGENTs) : concentrated H3PO4

7. Chemicals (REAGENTs) : NaOH pellets

8. Chemicals (REAGENTs) : distilled water

9. pRocedure 1 Prepare 3M, 100cc HNO3 solution using concentrated HNO3 (15.6 N)

10. pRocedure 1 80 mL H2O 19.23 mL conc. HNO3 0.8 mL H2O graduated cylinder beaker pipette pipette volumetric flask

11. RESULTS & Discussion Dilution formula: M1 V1 = M2 V2 15.6 (V1) = 3 (100) (V1) = 300/15.6 = 19.2 mL of conc. HNO3 Volume of conc. HNO3 : ____________ Volume of H2O : __________________ Molecular mass of HNO3 : __________ Mole of solute ( HNO3) : ____________ 80.8 mL 63 g/mol 19.2 mL 0.3 mol

12. Nitric Acids’ Properties : Molecular formula : HNO3 Apperance : colorless liquid Solubility in water : completely miscible Other characteristics: highly corossive acid made by reaction of NO2 and water From 19.23 mL of concentrated HNO3 and 80.8 mL of water, the solution that we produced by using the dilution method (Weakening or reducing the concentration by the addition of water) is 3M nitric acid solution (dilute) .

13. pRocedure 2 Prepare 1.5M, 100cc H2SO4 solution using concentrated H2SO4 (36N).

14. pRocedure 2 91.7 mL H2O 8.3 mL conc. H2SO4 graduated cylinder beaker pipette volumetric flask

15. RESULTS & Discussion Dilution formula: M1 V1 = M2 V2 18 (V1) = 1.5 (100) (V1) = 150/18 = 8.3 mL of conc. H2SO4 Volume of conc. H2SO4 : ____________ Volume of H2O : __________________ Molecular mass of H2SO4 : __________ Mole of solute ( H2SO4) : _______ 8.3 mL 91.7 mL 98 g/mol 0.15mol

16. Sulfurc Acids’ Properties : Molecular formula : H2SO4 Apperance : clear, colorless to slightly yellow viscous and odorless liquid Solubility in water : miscible Other characteristics: non-flammable but highly corossive . It is pungent-ethereal. It is also soluble in water in all concentrations. From 8.3 mL of concentrated H2SO4 and 91.7 mL of water, the solution that we produced by using the dilution method (Weakening or reducing the concentration by the addition of water) is 1.5M sulfuric acid solution (dilute) .

17. pRocedure 3 Prepare of 0.5N, 100cc H3PO4 solution using concentrated H3PO4 (44.4 N)

18. pRocedure 3 98.9 mL H2O 1.1 mL conc. H3PO4 graduated cylinder beaker pipette volumetric flask

19. RESULTS & Discussion Dilution formula: N1 V1 = N2 V2 44.4 (V1) = 0.5 (100) (V1) = 0.5 (100) / 44.4 = 1.1 mL of conc. H3PO4 Volume of conc. H3PO4 : ____________ Volume of H2O : __________________ Molecular mass of H3PO4 : __________ Mole of solute ( H3PO4) : ____________ Mass of H3PO4 : __________ 1.1 mL 98.9 mL 97.97 g/mol 1.64 g

20. Phosporic Acids’ Properties : Molecular formula : H3PO4 Apperance : viscous and colorless liquid Solubility in water : miscible Other characteristics: deliquescent, non-toxic acid which, in pure, is solid. From 1.1 mL of concentrated H3PO4 and 98.9 mL of water, the solution that we produced by using the dilution method (Weakening or reducing the concentration by the addition of water) is 0.5N phosphoric acid solution (dilute) .

21. pRocedure 4 Prepare 5 % 100cc NaOH solution.

22. pRocedure 4 5 g NaOH pellets Add 5 mL of distilled H2O weigh an empty watch glass Dissolve in 90 mL distilled water stir volumetric flask beaker Until obtaining 100 mL of 5% NaOH solution

23. RESULTS & Discussion Mass of NaOH pellets : ____________ Volume of H2O : __________________ 5 g 95 mL Using solubility method...

24. Sodium Hydroxide’s Properties : Molecular formula : NaOH pellets Apperance : white, waxy, opaque crystals, odorless Solubility in water : miscible Other characteristics: caustic, readily absorb moist when exposed. From 5 g of NaOH pellets and 95 mL of water, the solution that we produced by using the dissolution method is 5% sodium hydroxide solution (dilute) .

25. pRocedure 5 Prepare 25 %, 100cc NaOH solution.

26. pRocedure 5 25 g NaOH pellets Add 5 mL of distilled H2O weigh an empty watch glass Dissolve in 70 mL distilled water stir volumetric flask beaker Until obtaining 100 mL of 5% NaOH solution

27. RESULTS & Discussion Mass of NaOH pellets : ____________ Volume of H2O : __________________ 25 g 75 mL

28. Sodium Hydroxide’s Properties : Molecular formula : NaOH Apperance : white, waxy, opaque crystals, odorless Solubility in water : miscible Other characteristics: caustic, readily absorb moist when exposed. From 25 g of NaOH pellets and 80 mL of water, the solution that we produced by using the dilution method (Weakening or reducing the concentration by the addition of water) is 25% sodium hydroxide solution (dilute) .

29. pRocedure 6 Repeat procedure 4 and solve for the molality of solution.

30. SOLVING Molality : m = nA = wtA = 5g = 0.125 mol kgB mwA 40g/mol 0.095 kg kgB 0.095 kg = 1.32 m Volume of solution (L) : __0.1 L________________ Molecular mass of NaOH : __________ Mole of solute ( NaOH ) : ____________ Mass of solvent (kg) : ______0.095 kg____________ Molar concentration (m) : _____1.25 M_______ 40 g/mol 0.125 mol

31. VALUES LEARNED When making chemical solutions, always use the appropriate safety equipment. As a general rule, always add the more concentrated solution to the less concentrated solution. All chemicals that you are unfamiliar with should be treated with extreme care and assumed to be highly flammable and toxic. Label all prepared acid solutions before storing them with at least the name of the acid, concentration, hazard warning or how the acid can hurt you, and date prepared on the label.

32. GENERALIZATION in experiment 1, we have prepared 3M nitric acid by using dilution method where we added 80.8 mL of H2O to 19.23 mL conc. n itric acid. in experiment 2, we have prepared 1.5M sulfuric acid by using dilution method where we added 91.7 mL of H2O to 8.3 mL conc. sulfuric acid. in experiment 3, we have prepared 0.5N phosphoric acid by using dilution method where we added 98.9 mL of H2O to 1.1 mL conc. phosphoric acid . In the first three experiment, we have used the dilution method . It is the process where we weakens the concentration of the substance, but the amount of solute does not change.

33. GENERALIZATION : in experiment 4, we have prepared 5% sodium hydroxide solution by dissolving 5g NaOH pellets in 95 mL distilled H2O. in experiment 5, we have prepared 25% sodium hydroxide solution by dissolving 25g NaOH pellets in 75 mL distilled H2O . In the last two experiments, we have used the solubility method where a amount of substance is dissolved in a given quantity of solvent to form a saturated solution.

34. REFERENCES: http:// en.wikipedia.org/wiki/preparingsolutions Modules in GENERAL CHEMISTRY (Inorganic and Organic)