CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Autumn Examinations 2014
Module Title:
Laboratory Practices CA
Module Code:
OCCH6002
School :
Science
Programme Title:
B. Sc. in Analytical & Pharmaceutical Chemistry – Stage 1
B. Sc. in Analytical Chemistry with Quality Assurance – Stage 1
Programme Code:
SCHEM_7_Y1
SCHQA_8_Y1
External Examiner:
Internal Examiner:
Dr. C Roche
Dr. M. Sheahan
Instructions:
Answer FOUR questions as follows:
Answer Question 1 and three other questions
Duration:
2 Hours
Sitting:
Autumn 2014
Requirements for this examination:
Periodic Table
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have
received the correct examination paper.
If in doubt please contact an Invigilator.
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Q1.
(a) Using the underwritten guidelines, describe how to perform a titrimetric analysis
(i) Glassware requirements
(2 marks)
(ii) Labelled sketch apparatus set up
(3 marks)
(iii)Procedure
(4 marks)
(iv) End-point determination
(3 marks)
(v) Sources of error & how to minimize them
(4 marks)
(b) In an acid-base titration, a solution of ammonium hydroxide is neutralized by a
standard solution of hydrochloric acid
(i) Write an equation showing the neutralization reaction
(2 marks)
(ii) Define the underlined term
(3 marks)
(iii)If 7cm3 of 0.1M HCl neutralizes 20cm3 of a NH4OH solution, determine the
molar concentration of NH4OH; hence calculate the grams (g) of NH4OH per
litre of solution. Show all calculations
(4 marks)
Q2.
(a) Distinguish between the following pairs of terms:
(i) Ionizing and non-ionizing radiation
(ii) A saturated solution and a homogeneous solution
(iii)A chronic toxin and an acute toxin
(iv) A mutagen and a teratogen
(12 marks)
(b) Distinguish between an analytical solution and a general purpose solution in terms
of how they are prepared, the glassware used and their use in the laboratory. Support
your answer with examples
(6 marks)
(c) Write a note on three ways by which chemical carcinogenicity may be determined
(7 marks)
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Q3.
(a) Errors in scientific measurements can be categorized as systematic and random errors.
Distinguish between both types of errors. Discuss how errors can arise and outline
how they may be reduced or eliminated
(15 marks)
(b) Describe in detail the course of action which should be undertaken in the event of a
laboratory fire
(10 marks)
Q4.
(a) Distinguish between the ‘absorbance’ and the ‘absorptivity’ of a sample (5 marks)
(b) Give an equation which relates absorbance and absorptivity for a given sample. If a
0.05g/L solution has an absorbance of 0.3171 in a 1cm cuvette, calculate a value for
the absorptivity. Assign units to the absorptivity
(4 marks)
(c) What parameters are on the x- and y- axes respectively in infrared (IR) spectra? Give
the appropriate range for the values on each axis
(3 marks)
3
(d) 25cm of five standard dye solutions were prepared from a 50ppm stock solution of
the dye. The absorbance of each standard was recorded and is presented in the table.
Conc. of standards (ppm)
1
5
10
15
20
0.008 0.039 0.073 0.117 0.160
Absorbance
(i) Calculate the volume of stock solution required to prepare each standard solution
(show calculations).
Name the type of glassware which is suitable for the
preparation of these solutions
(3 marks)
(ii) Construct a standard calibration plot from the tabulated data
(5 marks)
(iii)A 5cm3 aliquot of a food dye solution of unknown concentration was transferred
to a 25cm3 volumetric flask and diluted to the mark; the absorbance was recorded
as 0.052. Determine the concentration of the unknown solution
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(5 marks)
Q5.
(a) What information is provided by each of the following safety sign
(5 marks)
(b) Answer all parts
(i) Express 34.5mg in terms of grams
(1 mark)
(ii) Convert 760g to grams
(1 mark)
(iii) How many mL in 1.4L?
(1 mark)
(iv) Convert 18L to liters
(1 mark)
(v) Is 698pg equivalent to 6.98 x 10-10 or 6.98 x 10-9 g?
(2 marks)
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(vi) Express 1.9 x 10 m in millimetres
(1 mark)
(vii) Give the wavelength range for the visible region
(2 marks)
(viii) Define an LD50 value and assign appropriate units to it. If substance A is more
toxic than substance B, which will have the higher LD50 value?
(ix) What is a threshold limit value?
(5 mark)
(3 marks)
(x) What is the concentration of a solution prepared by dissolving 5g of sodium
carbonate (Na2CO3) in water and diluting to 250cm3?
(3 marks)
Q6.
(a) Name three routes by which chemicals can enter the body. Identify the most common
route?
(4 marks)
(b) Write a comprehensive note on material safety sheets (MSDS)
(6 marks)
(c) Identify the hazards and discuss the precautions which must be observed when
working with the following in the laboratory.
(i) Solvents
(4 marks)
(ii) Corrosive materials
(4 marks)
(iii)Radiation
(7 marks)
Support your answers with appropriate examples
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