2. A solution that may contain Cu", Bi?", Sn, or Sb?* is treated with thioacetamide in an acidic medium. The black precipitate which forms is partly soluble in strongly basic solution. The precipitate which remains is soluble in 6 M HNO; and gives only a white precipitate upon the addition of NH¸OH. The basic solution, when acidified, produces an orange precipitate.. Which group II ions are present? Which are absent? Which are in doubt? How would you remove all doubt?

2. A solution that may contain Cu", Bi?", Sn, or Sb?* is treated with thioacetamide in an acidic medium. The black precipitate which forms is partly soluble in strongly basic solution. The precipitate which remains is soluble in 6 M HNO; and gives only a white precipitate upon the addition of NH¸OH. The basic solution, when acidified, produces an orange precipitate.. Which group II ions are present? Which are absent? Which are in doubt? How would you remove all doubt?

Chemical Principles in the Laboratory

11th Edition

ISBN:9781305264434

Author:Emil Slowinski, Wayne C. Wolsey, Robert Rossi

Publisher:Emil Slowinski, Wayne C. Wolsey, Robert Rossi

Chapter37: Qualitative Analysis Of Group Ii Cations

Section: Chapter Questions

Problem 3ASA

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A solution that may contain Cu2+ , Bi2+ , Sn4+ , or Sb2+ is treated with thioacetamide in an acidic medium. The black precipitate which forms is partly soluble in strongly basic solution. The precipitate which remains is soluble in 6 M HNO3 and gives only a white precipitate upon the addition of NH4OH. The basic solution, when acidified, produces an orange precipitate. Which group II ions are present? Which are absent? Which are in doubt? How would you remove all doubt?
You have been sent to India to investigate the occurence of goiter disease attributed to iodine deficency. As part of of your investigation, you must make field measurements of traces of Iodide(I-) in groundwater. The procedure is to oxidize I- to I2 and convert the I2 into an intensely colored complex with the dye brilliant green in the organic solvent toluene. a) A 3.15x10^-6 M solution of the colored complex exhibited an absorbance of 0.267 at 635nm in a 1.00cm cuvet. A blank solution made from distilled water in place of groundwater had an absorbance of 0.019. Find the molar absroptivity of the colored complex. b)The absorbance of an unknown solution prepared from ground water was 0.175. Find the concentration of the unknown.
The following is an experimental account of the preparation of compound B from Phenylamine. 2cm3 of phenylamine are dissolved in 10cm3 of 0.5M hydrochloric acid in a test tube and cooled in an ice bath. 5cm3 of 0.2M sodium nitrate solution cooled to about 5o are added to the solution above and shaken. A salt A, C6H5N2Cl is formed, collected and dried. 1g of salt A is dissolved in 10cm3 of water, cooled and added drop by drop to a cold solution of 0.3g phenol in 5cm3 of 0.1M sodium hydroxide solution. B is precipitated, filtered, dried and the melting point determined. B is further crystallized twice and the melting point taken each time and found to be constant. Questions: (i) Give the name and suggest the colour of the precipitate B. Hence explain why it is necessary to recrystallize B several times. (ii) Why was it necessary to obtain a constant melting point for B?
The following is an experimental account of the preparation of compound B from Phenylamine. 2cm3 of phenylamine are dissolved in 10cm3 of 0.5M hydrochloric acid in a test tube and cooled in an ice bath. 5cm3 of 0.2M sodium nitrate solution cooled to about 5o are added to the solution above and shaken. A salt A, C6H5N2Cl is formed, collected and dried. 1g of salt A is dissolved in 10cm3 of water, cooled and added drop by drop to a cold solution of 0.3g phenol in 5cm3 of 0.1M sodium hydroxide solution. B is precipitated, filtered, dried and the melting point determined. B is further crystallized twice and the melting point taken each time and found to be constant. 1g of phenylamine yielded 1.2g of compound A. Calculate the percentage yield of the reaction.
The following is an experimental account of the preparation of compound B from Phenylamine. 2cm3 of phenylamine are dissolved in 10cm3 of 0.5M hydrochloric acid in a test tube and cooled in an ice bath. 5cm3 of 0.2M sodium nitrate solution cooled to about 5o are added to the solution above and shaken. A salt A, C6H5N2Cl is formed, collected and dried. 1g of salt A is dissolved in 10cm3 of water, cooled and added drop by drop to a cold solution of 0.3g phenol in 5cm3 of 0.1M sodium hydroxide solution. B is precipitated, filtered, dried and the melting point determined. B is further crystallized twice and the melting point taken each time and found to be constant. Why was it necessary to obtain a constant melting point for B?
The following is an experimental account of the preparation of compound B from Phenylamine. 2cm3 of phenylamine are dissolved in 10cm3 of 0.5M hydrochloric acid in a test tube and cooled in an ice bath. 5cm3 of 0.2M sodium nitrate solution cooled to about 5o are added to the solution above and shaken. A salt A, C6H5N2Cl is formed, collected and dried. 1g of salt A is dissolved in 10cm3 of water, cooled and added drop by drop to a cold solution of 0.3g phenol in 5cm3 of 0.1M sodium hydroxide solution. B is precipitated, filtered, dried and the melting point determined. B is further crystallized twice and the melting point taken each time and found to be constant. Give the structure of the product formed when an acidified solution of compound A is reacted with (i)Naphthalen-2-ol (2-naphthol) (ii) Sodium cyanide
The following is an experimental account of the preparation of compound B from Phenylamine. 2cm3 of phenylamine are dissolved in 10cm3 of 0.5M hydrochloric acid in a test tube and cooled in an ice bath. 5cm3 of 0.2M sodium nitrate solution cooled to about 5o are added to the solution above and shaken. A salt A, C6H5N2Cl is formed, collected and dried. 1g of salt A is dissolved in 10cm3 of water, cooled and added drop by drop to a cold solution of 0.3g phenol in 5cm3 of 0.1M sodium hydroxide solution. B is precipitated, filtered, dried and the melting point determined. B is further crystallized twice and the melting point taken each time and found to be constant. Question: Answer both (i) and (ii) below (i) Give the structure of the product formed when an acidified solution of compound A is reacted with Naphthalen-2-ol (2-naphthol) and Sodium cyanide separately (ii) 1g of phenylamine yielded 1.2g of compound A. Calculate the percentage yield of the reaction.
The following is an experimental account of the preparation of compound B from Phenylamine. 2cm3 of phenylamine are dissolved in 10cm3 of 0.5M hydrochloric acid in a test tube and cooled in an ice bath. 5cm3 of 0.2M sodium nitrate solution cooled to about 5o are added to the solution above and shaken. A salt A, C6H5N2Cl is formed, collected and dried. 1g of salt A is dissolved in 10cm3 of water, cooled and added drop by drop to a cold solution of 0.3g phenol in 5cm3 of 0.1M sodium hydroxide solution. B is precipitated, filtered, dried and the melting point determined. B is further crystallized twice and the melting point taken each time and found to be constant. Write the equation for the reaction between compound A and phenol Give the name and suggest the colour of the precipitate B. Why is it necessary to recrystallize B several times?
The following is an experimental account of the preparation of compound B from Phenylamine. 2cm3 of phenylamine are dissolved in 10cm3 of 0.5M hydrochloric acid in a test tube and cooled in an ice bath. 5cm3 of 0.2M sodium nitrate solution cooled to about 5o are added to the solution above and shaken. A salt A, C6H5N2Cl is formed, collected and dried. 1g of salt A is dissolved in 10cm3 of water, cooled and added drop by drop to a cold solution of 0.3g phenol in 5cm3 of 0.1M sodium hydroxide solution. B is precipitated, filtered, dried and the melting point determined. B is further crystallized twice and the melting point taken each time and found to be constant. (a) What is the general name given to the reaction between phenylamine and sodium nitrite and explain why it's necessary to carry out the reaction at low temperatures. (b) Write the equation for the reaction between compound A and phenol
The following is an experimental account of the preparation of compound B from Phenylamine. 2cm3 of phenylamine are dissolved in 10cm3 of 0.5M hydrochloric acid in a test tube and cooled in an ice bath. 5cm3 of 0.2M sodium nitrate solution cooled to about 5o are added to the solution above and shaken. A salt A, C6H5N2Cl is formed, collected and dried. 1g of salt A is dissolved in 10cm3 of water, cooled and added drop by drop to a cold solution of 0.3g phenol in 5cm3 of 0.1M sodium hydroxide solution. B is precipitated, filtered, dried and the melting point determined. B is further crystallized twice and the melting point taken each time and found to be constant. What is the general name given to the reaction between phenylamine and sodium nitrite and explain why it's necessary to carry out the reaction at low temperatures? Write the equation for the reaction between compound A and phenol Write the equation for the reaction between phenylamine and sodium nitrite.
copper complex crystallises straightaway when synthesising but the cobalt complex required the solution to be concentrated and cooled before it is filtered to obtain product. what does this tell you about the realtive solubilities of the copper and cobalt complexes.
If PbCl2 was not completely removed by hot water from the first group precipitate, what will become of it when the residue is treated with NH4OH?