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Re-Crystallization of Boric Acid

The purpose to carry out this lab is recrystallization of solid and then identify the effect on solids purity and produce.

Part A: Reactions

Table 1. quantitative and qualitative observations of reactions to form boric acid.

Mass of borax (g)

10. 0558g

Appearance of borax

White powder

Time for solubility of borax (min)


Time for boric acid crystals to form (min)


Part B: Filtration

Table 2. mass of watch cup and filter paper, mass of watch glass, filter newspaper and moist crystals from filtration and qualitative observations of crystals after purification.

Mass of watch wine glass1 an filtration system paper1(g)

33. 3364g

Mass of damp crystals, watch a glass 1, filter paper from purification(g)

44. 6083g

Appearance of crystals after filtration

Soft, white sound formation.

Part C: Re-crystallization

Table 3. mass of watch glass and filter paper, mass of watch glass, filter paper ad moist crystals from recrystallization, and qualitative observations of crystals after recrystallization

Mass of watch goblet2 and filtration paper2(g)

25. 2834g

Mass of watch glass2, filter newspaper2 and recrystallization (g)

28. 0524g

Appearance of crystals after recrystallization

White glistening crystal in sound.

Part D: Purity test

Table 4. qualitative observations for the purity test of crystals collected after purification and recrystallization

Observations of test tube 1, filled with crystals after purification, after reacting with AgNO3

Observations of test pipe 2, containing crystals after recrystallization, after reacting with AgNO3

White precipitates shaped cl- are present, AgCl formed.

Solution is clear, Cl- are not present.

Table 5. mass of watch cup, filter newspaper and crystals, and qualitative observations of crystals, after recrystallization and drying.

Mass of watch glass 2 + filtration paper2+dried crystals from recrystallization (g)

27. 4848g

Appearance of crystals

White solid formation, shining to look at.

  1. Calculate the wet mass of crystals following the purification and the recrystallization, and dry mass of crystals following the recrystallization. summarize your results on ONE table (you ought to have 3 masses documented in this stand)
  2. Write the well-balanced chemical equation for the a reaction to produce boric acid. Determine which reactants the restricting reagent. Show all of your work.
  3. Calculate the theoretical yield of boric acid. show all of your work.
  4. Calculate the yield of boric acid based on the dry mass of the crystals.
  5. Calculate the solubility of boric acid in the at 250C and 800C using the equations of the best-fit curves that are located in figure 3-2.
  1. Explain Why drinking water was an appropriate solvent to use for recrystallization in this lab.
  2. Explain the variations observed in the appearance of the crystals after filtration compared to the crystals after recrystallization
  3. a) Explain the way the purity test is employed in this lab to determine the purity of the product (include a balanced chemical formula in your answer).

b) predicated on your observations, are the crystals that you accumulated following recrystallization 100 % pure? Make clear your answer.

  1. Other than accomplishing the purity test that was performed in this experiment, explain two other methods that can be used to determine the purity of something.
  2. Discuss the percent yield result. Fully explain two reasons (sources of problem) for the increased loss of product through the experiment, like the specific step at which product was lost. Also describe how each one of the losses can be minimized.
  3. If you recrystallized the crystals again, what would you expect to happen? Explain your answer.
  4. If during crystallization the solute fails to crystallize, what can be done to include the crystals to form? Explain two ways to cause crystal formation.
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