Arsenic(III) oxide (As2O3) is available in pure form and is a useful (but carcinogenic) primary standard for oxidizing agents such as MnO4-. The As2O3 is dissolved in base and then titrated with MnO4- in acidic solution. A small amount of iodide (I - ) or iodate (IO3-) is used to catalyze the reaction between H3AsO3 and MnO4-.As2O3 + 4 OH -  2 HAsO32- + H2OHAsO32- + 2 H+  H3AsO35 H3AsO3 + 2 MnO4- + 6 H+  5 H3AsO4 + 2 Mn2+ + 3 H2O(a) A 3.209 g aliquot of KMnO4 (FM 158.034) was dissolved in 1.000 L of water, heated to cause any reactions with impurities to occur, cooled and filtered. What is the theoretical molarity of this solution if no MnO4- was consumed by impurities?  M(b) What mass of As2O3 (FM 197.84) would be just sufficient to react with 25.00 mL of the KMnO4 solution in part (a)?  g(c) It was found that 0.146 8 g of As2O3 required 29.98 mL of KMnO4 solution for the faint color of unreacted MnO4- to appear. In a blank titration, 0.03 mL of MnO4- was required to produce enough color to be seen. What is the molarity of the permanganate solution?  M

Question
Asked Oct 5, 2019
149 views

Arsenic(III) oxide (As2O3) is available in pure form and is a useful (but carcinogenic) primary standard for oxidizing agents such as MnO4-. The As2O3 is dissolved in base and then titrated with MnO4- in acidic solution. A small amount of iodide (I - ) or iodate (IO3-) is used to catalyze the reaction between H3AsO3 and MnO4-.

As2O3 + 4 OH -  2 HAsO32- + H2O
HAsO32- + 2 H+  H3AsO3
5 H3AsO3 + 2 MnO4- + 6 H+  5 H3AsO4 + 2 Mn2+ + 3 H2O
(a) A 3.209 g aliquot of KMnO4 (FM 158.034) was dissolved in 1.000 L of water, heated to cause any reactions with impurities to occur, cooled and filtered. What is the theoretical molarity of this solution if no MnO4- was consumed by impurities?
  M

(b) What mass of As2O3 (FM 197.84) would be just sufficient to react with 25.00 mL of the KMnO4 solution in part (a)?
  g

(c) It was found that 0.146 8 g of As2O3 required 29.98 mL of KMnO4 solution for the faint color of unreacted MnO4- to appear. In a blank titration, 0.03 mL of MnO4- was required to produce enough color to be seen. What is the molarity of the permanganate solution?
  M
check_circle

Expert Answer

Step 1

(a) Given that,

Weight of KMnO4 is 3.209 g.

The molar mass of KMnO4 is 158.034 g/mol.

Volume of the solution is 1.000 L.

The number of moles of KMnO4 can be evaluated as,

Thus, the moles of KMnO4 is 0.0203 mol.

help_outline

Image Transcriptionclose

weight of KMnO Moles of KMnO 4 molar mass of KMnO 4 3.209 g 1-1 158.034 g-mol- 0.0203 mol

fullscreen
Step 2

Since, 1 L of 1 M KMnO4 should contain 158.034 g.

Therefore, if the weight is 3.209 g in 1 L, the theoretical molarity can be calculated as follows:

Hence, the theoretical molarity of the solution is 0.0203 M.

help_outline

Image Transcriptionclose

moles of KMnO 4 Theoretical molarity = volume of solution in L 0.0203 mol 1.000 L =0.0203 M

fullscreen
Step 3

(b) Write the standardized reaction as follows:

The volume of the KMnO4 solution is 25 mL.

The molarity is 0.0203 M.

N...

help_outline

Image Transcriptionclose

SAs,02+4Mnl+9H,0 + 12H+ -> 10H^AsO4 +4Mn2 Moles of KMno, =molarity x volume 4 =(0.0203 x 103 mol-mL x 25 mL =0.5075 x 10-3 mol

fullscreen

Want to see the full answer?

See Solution

Check out a sample Q&A here.

Want to see this answer and more?

Solutions are written by subject experts who are available 24/7. Questions are typically answered within 1 hour.*

See Solution
*Response times may vary by subject and question.
Tagged in

Science

Chemistry

Related Chemistry Q&A

Find answers to questions asked by student like you
Show more Q&A
add
question_answer

Q: 3H2(g)+N2(g)  to 2NH3(g) What is the theoretical yield in grams for this reaction under the given ci...

A: Ammonia is synthesized from Hydrogen and Nitrogen gasThe balanced equation shown below

question_answer

Q: What is the electron configuration for iodine 131 isotope

A: The arrangement of electrons in an atom with increasing order of energy level is considered as elect...

question_answer

Q: How many grams K3PO4 contains 2.364 moles potassium atoms?

A: Given:Number of moles potassium atoms = 2.364 moles.Molar mass of K3PO4 = 212.27 g/mol.

question_answer

Q: Choose all the common ions that are isoelectronic with Ne?    Na+    O2−    Br−    Mg2+ ...

A: Isoelectronic is defined as atoms, ions, or molecules that are same number of valance electrons and ...

question_answer

Q: how do you draw a structure of an alkane or cycloalkane that has more than three but fewer than ten ...

A: Method to draw a structure of an alkane or cycloalkane that has more than three but fewer than ten c...

question_answer

Q: Solid silver can be produced by reacting silver (I) nitrate with copper according to the reaction be...

A: Number of mol of Cu used = given mass / molecular mass =17.788 g /(63.55 g/mol) = 0.279 mol.

question_answer

Q: When a sample of cyclohexene is burned in oxygen, 4.822 g of CO2 and 1.650 g of H2O are obtained. Wh...

A: The term combustion reactions refer to those type of chemical reaction in which a hydrocarbon reacts...

question_answer

Q: 7. Methanol, ethanol, and n-propanol are three common alcohols. When 1.00 g of each of these alcohol...

A: (a)The heat combustion value of methanol is determined as follows,

question_answer

Q: The 235U isotope undergoes fission when bombarded with neutrons. However, its natural abundance is o...

A: According to Graham’s law, if a mixture contains two gases, then the rate of effusion at constant pr...