Could you please answer these questions 1. ++++ 2- +++++ 3- Thank you The flask

Question

Could you please answer these questions

1.

++++

2-

+++++

3-

Thank you

The flask shown here contains 0.130 g of acid and a lew drops of phenolphthalein indicator dissolved in water. The buret contains 0.160 M NaOH. What volume of base is needed to reach the end point of the titration? Assuming the acid is monoprotic, what is its molar mass? Add base to the solution until it just turns pink. You may need to reset the titration if you go past the end point. The flask shown here contains 0.669 g of acid and a few drops of phenolphthalein indicator dissolved in water. The buret contains 0.270 M NaOH. What volume of base is needed to reach the end point of the titration? What is the molar mass of the acid (assuming it is diprotic and that the end point corresponds to the second equivalence point)? Add base to the solution until it just turns pink. You may need to reset the titration if you go past the end point. Phosphorous acid, H3PO3(aq), is a diprotic oxyacid that is an important compound in industry and agriculture. Calculate the pH for each of the following points in the titration of 50.0 mL of a 1.8 M H3PO3(aq) with 1.8 M KOH(aq).

Explanation / Answer

Answer 1) a

Volume of Base used indicated by the given picture = 13 ml
Volume of base is needed to reach the end point of the titration = 13 ml

Answer 1)b

Moles of base = Volume * molarity = 0.013 * 0.160 = 0.00208 mole

Moles of acid = Moles of base = 0.00208

Molecular weight = Mass / Moles = 0.130 g /0.00208 mole = 62.5 g/mol

the acid is monoprotic, its molar mass = 62.5 g/mol

Answer 2)

Here we take the acid to be H2A.

H2A + 2 NaOH = > Na2A + 2H2O

Also the Moles of NaOH = volume * concentration of NaOH

= 27 /1000 * 0.270 = 0.00729 moles

molar mass of H2A = given mass / moles of H2A = 0.669 / 0.00729 moles =91.76 g/ mol

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