BSc Chemistry SEM III 2018 2019 2019 Chemistry III Question Paper - Mumbai University | munotes

Questions asked in this paper

1. Q1 A. Fill in the blanks with suitable option and rewrite the statement (any TWELVE) 12 marks
   • i. Chemical analysis is called semi-micro scale analysis, when sample taken per test is
   • ii. By calibration of apparatus errors can be minimized ili. Blowing of a pipette is error
   • iv. Spectrophometric measurements belong to method of analysis
   • v. DTAisa method of analysis
   • vi. Sample is a small representative replica of
   • vii. For Acetic acid vs NaOH titration is used as indicator Ostwald’s ripening refers to of precipitate
   • ix. The neutralization of weak acid and strong base titration will be at pH
   • a. 7 b. less than 7 c. more than 7
   • x. During titration the solution in the burette is called
   • xi. Complexometric titrations are titration between EDTA and
   • xii. In thermogravimetry the weight of sample is recorded as a function of Absorbance and transmittance of an absorbing solution are related by the
   • xiv. Bathochromic effect is the shift in absorption to
   • xv. Wavelength of ultra-violet light is
   • a. 400 to 750 nm b. 200 to 400 nm c. 400 to 750 m XVi. cuvettes are used for analysis in UV region XVii. Colorimeter is useful only in region In photometric titrations, is plotted against volume of titrant added
   • B. State whether the following statements are true or false (any Three) 3
   • 1) The instrumental analysis is also known as classical analysis
   • ii) Analytical sample means the sample subjected to analysis
   • iii) All precipitates are required to be heated above for drying
   • iv) Equivalence point and end point are always the same Colorimeters are more sensitive than Spectrophotometers
   • vi) Cis and trans isomers can be distinguished using UV-visible spectroscopy
   • C. Match the following: (any Five) 5
   • 1. Digestion a. Impurity in precipitate
   • 5. Volumetric analysis e. I:
   • 6. Cell Constant f. Increase in particular size
   • g. Separation technique
2. Q2 Answer any Four of the following sub-questions 20 marks
   • a. Compare the advantages and limitations of classical method of analysis with instrumental method of analysis
   • b. What is error? Distinguish between determinate and indeterminate errors
   • c. What is sub-sample? Discuss coning and quartering method to reduce the sample size of solid
   • d. The Copper content of the ETP of electroplating industry was recorded for five times in a day to get following data: Calculate absolute and relative error for above data if the true value is 9.8 ppm
   • e. With the help of a suitable diagram explain tools used for sampling of gases
   • f. Discuss the methods of minimizing the errors
3. Q3 Answer any Four of the following sub-questions 20 marks
   • a. What are the various types of titrations? Give one example each
   • b. Discuss the criteria for selection of an indicator in acid — base titrations
   • c. K 10.0 cm? of acetic acid is titrated against 0.1 M sodium hydroxide Calculate the pH of the solution on (Ka= 1.8 x
   • (i) Addition of 7.0 cm? sodium hydroxide from the burette Addition of sodium hydroxide from the burette
   • d. What is co-precipitation and post precipitation? How can it be avoided?
   • e. Discuss various types of gravimetric analysis giving one example each
   • f. Define standard solution. How are they prepared? Distinguish between primary standard and
4. Q4 Answer any Four of the following sub-questions 20 marks
   • a. Discuss the principle and experimental set-up for performing photometric titrations
   • b. With the help of suitable diagram explain working of single beam spectrophotometer?
   • c. 3.2x 107M solution of substance has a transmittance of 0.805 when measured at 525 nm in a cell with path length of 1 cm. Calculate the absorbance of the solution if its concentration is double of its original concentration
   • d. How are Cu(II) and estimated in a mixture using photometric titration?
   • e. Explain the calibration curve method of quantitative analysis. How is the concentration of unknown solution calculated without plotting the graph?
   • f. How are organic functional groups identified using UV — Visible spectrometry
5. Q5 Answer any four of the following. 20 marks
   • a. Discuss the sampling of stationery and flowing liquids
   • b. What are the different methods of instrumental analysis?
   • c. Discuss the importance of calibration of volumetric apparatus? How is 100 cm? standard flask is
   • d. Calculate the normality (N) of the following molar solutions:
   • (v) 0.10 M oxalic acid
   • e. Explain the working of “photo multiplier tube with the help of a diagram”. What are. its
   • f. List the fundamental differences between colorimeter and spectrophotometer

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