Chemistry Quiz: Standard Solutions and Titration
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Questions and Answers

Which of the following is the function of the chopper in Atomic Absorption Spectroscopy?

  • To break the steady light into pulsating light (correct)
  • To reduce the sample into atomic state
  • To filter unwanted components
  • To split the beam into two

    • Atomic absorption spectroscopy is also called as

  • Raman spectroscopy
  • Fluorimetry
  • None
  • Absorption Flame Photometry (correct)

    • Atomic Absorption Spectroscopy is used for the analysis of

  • Metal (correct)
  • Hydrogen
  • Carbon
  • Nitrogen

    • At what pressure should the gases in the sealed tube be maintained in the Hollow cathode lamp?

    <p>1 to 5 torr</p> Signup and view all the answers

    In Total consumption burner, only samples of a particular droplet size will enter the burner.

    <p>False</p> Signup and view all the answers

    Liquid chromatography can be performed in which of the following ways?

    <p>Either in columns or on plane surfaces</p> Signup and view all the answers

    Gas chromatography can be performed in which of the following ways?

    <p>Only in columns</p> Signup and view all the answers

    In Gas-liquid phase chromatography, the stationary phase is composed of and the mobile phase is made of:

    <p>Liquid, liquid</p> Signup and view all the answers

    Which of the following types of chromatography involves the process where the mobile phase moves through the stationary phase by the influence of gravity or capillary action?

    <p>Planar Chromatography</p> Signup and view all the answers

    What is the nature of the mobile phase in reverse phase chromatography?

    <p>Non-polar</p> Signup and view all the answers

    The absorption maximum for polar compounds is usually shifted with change in polarity of the solvents due to

    <p>Hydrogen bonding</p> Signup and view all the answers

    A compound has a molecular weight of 297; an equivalent weight of 148.5 and an A (1%, 1cm) of 742 at 309 metre. What is its absorptivity?

    <p>220.37</p> Signup and view all the answers

    Glass cells are not used for UV spectrophotometry below 340 nm because glass?

    <p>Absorbs the radiation</p> Signup and view all the answers

    Colorimeters are used in applications where great accuracy is required.

    <p>False</p> Signup and view all the answers

    In photometers, the readings of the specimen are initially obtained in the form of which of the following parameters? ________

    <p>Transmittance</p> Signup and view all the answers

    Colorimeters are used to determine

    <p>Concentration of solution</p> Signup and view all the answers

    Match the following programming languages with their primary usage:

    <p>Python = General-purpose programming JavaScript = Client-side scripting for web applications SQL = Database queries CSS = Styling web pages</p> Signup and view all the answers

    Retention factor is also known as...

    <p>Capacitance factor</p> Signup and view all the answers

    What must be the value of selectivity factor?

    <p>Greater than 1</p> Signup and view all the answers

    Which of the following is the distance that the solute moves while undergoing one partition?

    <p>Plate height</p> Signup and view all the answers

    Which of the following conditions will cause the efficiency of the column to increase?

    <p>Plate number becomes greater, plate height becomes smaller</p> Signup and view all the answers

    Tailing occurs due to

    <p>All</p> Signup and view all the answers

    In gas-liquid chromatography, when films are used in the interior of capillary column, the value of Eddy diffusion is zero.

    <p>True</p> Signup and view all the answers

    Which of the following is the disadvantage of reciprocating pump used in liquid chromatography?

    <p>Produces pulsed flow</p> Signup and view all the answers

    Which of the following will improve the efficiency of separation process in liquid chromatography?

    <p>Reduction in sample size, reduction in column diameter</p> Signup and view all the answers

    Which of the following columns are not used in liquid or high performance liquid chromatography?

    <p>Capillary column</p> Signup and view all the answers

    Pure water is known to be which of the following?

    <p>weak electrolyte</p> Signup and view all the answers

    UV-Visible detectors in liquid chromatography may have cells made of silica.

    <p>False</p> Signup and view all the answers

    What is the formula for pH calculation?

    <p>-log10[H+]</p> Signup and view all the answers

    Standardization of 0.1 N HCl is done against which substance?

    <p>AR silver nitrate</p> Signup and view all the answers

    If a compound has a pH of 6.5, what is its pOH?

    <p>7.5</p> Signup and view all the answers

    If a solution conducts electricity, it is probably:

    <p>An acid</p> Signup and view all the answers

    What is the pH of a 0.001M formic acid solution? (Ka=1.8×10^-4)

    <p>3.37</p> Signup and view all the answers

    What is the concentration of Ag ion in a saturated silver chloride solution? (Ksp = 1.56 x 10^-10)

    <p>1.25 x 10^5 M</p> Signup and view all the answers

    All of the following drugs are assayed by non-aqueous titration EXCEPT:

    <p>Cycloserine</p> Signup and view all the answers

    Why are the pipette, burette, and conical flask rinsed with deionised water instead of tap water?

    <p>To avoid interference from ions present in tap water that may affect the titration result.</p> Signup and view all the answers

    Method for the assay of ascorbic acid IP is:

    <p>Cerric ammonium sulphate oxidation</p> Signup and view all the answers

    Thiamine HCl IP is assayed by:

    <p>Fluorimetry</p> Signup and view all the answers

    The end point of complexometric titration is shown by means of:

    <p>PH indicators</p> Signup and view all the answers

    In standard solution, which of the following is accurately known?

    <p>Volume</p> Signup and view all the answers

    The process of adding known concentration until it completes the reaction with known volume is called as

    <p>Titration</p> Signup and view all the answers

    In titration, the end point can be determined by a change in color by

    <p>Indicator</p> Signup and view all the answers

    The quantity of chemical in each liter of solution is known as

    <p>Normality</p> Signup and view all the answers

    Exactly required concentration can be prepared from chemical reagent is called as

    <p>Primary standard</p> Signup and view all the answers

    Before performing the titration, two pieces of apparatus should be washed with the solution they are to contain, what are these two pieces of apparatus?

    <p>Burette &amp; Pipette</p> Signup and view all the answers

    If 25 ml 0.1 M solution of HCl was diluted to 500 ml, what is the new concentration of the HCI solution?

    <p>0.005 M</p> Signup and view all the answers

    A bottle labeled 20% CuSO4 contains 200 ml of solution. How many grams of CuSO4 are present in this solution?

    <p>40</p> Signup and view all the answers

    Normality is defined as

    <p>Gram-equivalent of the solute per liter of solution</p> Signup and view all the answers

    The number of gram moles of solute per liter of solution is

    <p>Molarity</p> Signup and view all the answers

    The number of gram moles of solute per kilogram of solution is

    <p>Molality</p> Signup and view all the answers

    The number of ml of a liquid solute per 100 ml of solution is

    <p>% weight by volume</p> Signup and view all the answers

    The weight of a substance in grams that reacts with 1 gram of Hydrogen molecules, 8 grams of oxygen molecules, or 35.5 grams of chlorine molecules is

    <p>Equivalent weight</p> Signup and view all the answers

    Normality of acid is calculated as

    <p>Molarity x Basicity</p> Signup and view all the answers

    Normality of bases is calculated as

    <p>Molarity x Basicity</p> Signup and view all the answers

    At the end of a titration to find the molarity of an HCl solution, if the volume of acid used is 14.4 ml, volume of base used is 22.4 ml, and molarity of the standard base is 0.2 M, what is the molarity of the acid solution?

    <p>0.31 M</p> Signup and view all the answers

    How many grams are required to make 500 ml of 0.1 N KMnO4 solution in an acidic medium?

    <p>1.58 gram</p> Signup and view all the answers

    Study Notes

    Here are the study notes for the text:

    • Standard Solution and Titration*
    • A standard solution is a solution of known concentration, used to determine the concentration of another solution.
    • Titration is a process of determining the concentration of a solution by reacting it with a standard solution.
    • Types of titration:
      • Acid-base titration
      • Redox titration
      • Complexometric titration
    • Normality, Molarity, Molality, and Mole Fraction*
    • Normality (N): the number of gram equivalents of solute per liter of solution.
    • Molarity (M): the number of moles of solute per liter of solution.
    • Molality (m): the number of moles of solute per kilogram of solvent.
    • Mole fraction (x): the number of moles of solute per total number of moles in the solution.
    • Acid-Base Titration*
    • The endpoint of acid-base titration is determined by a pH indicator, such as phenolphthalein or methyl orange.
    • The pH at the endpoint of acid-base titration is 7.
    • Strong Acid-Strong Base Titration*
    • The reaction between a strong acid and a strong base is complete and irreversible.
    • The pH at the endpoint of strong acid-strong base titration is 7.
    • Indicator and pH Range*
    • Indicators are substances that change color in response to a change in pH.
    • pH range of indicators:
      • Methyl orange: 3.1-4.4
      • Phenolphthalein: 8.3-10.0
    • Spectroscopy*
    • Spectroscopy is the study of the interaction between electromagnetic radiation and matter.
    • Types of spectroscopy:
      • Ultraviolet (UV) spectroscopy
      • Visible spectroscopy
      • Infrared (IR) spectroscopy
      • Nuclear Magnetic Resonance (NMR) spectroscopy
    • Properties of electromagnetic radiation:
      • Wavelength (λ)
      • Frequency (ν)
      • Speed (c)
      • Energy (E)
    • Beer-Lambert's Law*
    • Beer-Lambert's law relates the absorption of radiation to the concentration of a solution.
    • A = εbc, where A is the absorbance, ε is the molar absorptivity, b is the path length, and c is the concentration.

    Let me know if you'd like me to add or clarify anything!### Beer's Law and Spectroscopy

    Beer's Law

    • Establishes a relationship between absorbance and concentration of a sample
    • Derived assuming monochromatic radiation, which means if bandwidth increases, it will create deviation
    • States that the intensity of light decreases with the concentration of the medium
    • Represented as A = abc, where 'a' represents the absorption constant (absorptivity)

    Lambert's Law

    • States that the intensity of light decreases with respect to path length
    • Represented by the equation A = abc, where 'b' represents distance

    Absorption Spectroscopy

    • Involves transmission, where some radiation is absorbed and the rest is transmitted
    • Reflection and scattering are kept to a minimum
    • Amount of absorption depends on the number of molecules in the material
    • Intensity indication of concentration

    Transmittance

    • Given by TP/P, where P represents radiant power transmitted by the sample
    • No unit for absorbance, as units of absorptivity, distance, and concentration cancel each other out

    Molar Absorptivity (a)

    • Unit is L/mol/cm
    • Used to determine absorbance in Beer-Lambert's formula

    Instrumentation

    • Radiation source: tungsten lamp
    • Detectors: photomultiplier tube, photovoltaic cell, photoemissive tubes
    • Single beam instruments: do not use beam splitters
    • Double beam instruments: use beam splitters to split the beam into two equal intensity beams

    Applications

    • Colorimetry: used for determining concentrations of solutions, not for colour measurement
    • UV-Visible spectroscopy: used for determining concentrations of solutions
    • IR spectroscopy: used for functional group identification and qualitative analysis

    Infrared (IR) Spectroscopy

    • Types of IR spectroscopy: near IR, mid IR, far IR
    • Near IR: 0.8-2.5 mm
    • Mid IR: 2.5-50 mm
    • Far IR: 50-1000 mm
    • Sources: Nernst glower, Globar rod
    • Detectors: bolometer, thermistor

    Fourier Transform Infrared (FTIR) Spectrophotometer

    • A type of non-dispersive instrument
    • Uses a beam splitter to split the beam into two
    • Detector: pyroelectric transducer or pyroelectric crystals
    • Drive mechanism: moves the mirror to obtain a satisfactory interferogram
    • Advantages: high signal to noise ratio, information on all frequencies can be obtained, data retrieval is possible

    Atomic Absorption Spectroscopy (AAS)

    • Principle: radiation is absorbed by non-excited atoms in vapour state, exciting them to higher states

    • Radiation source: hollow cathode lamp

    • Function of chopper: breaks steady light into pulsating light

    • Function of flame or emission system: reduces the sample into atomic state

    • Detector: measures the absorbed radiation### Pressure Regulators and Flame Emission Photometers

    • Pressure regulators maintain a steady, flicker-free flame.

    • Pressure gauges indicate the pressure in a system.

    Flame Emission Photometers

    • Measure the colour and intensity of the flame when a sample is introduced.
    • Used for qualitative and quantitative analysis.
    • Qualitative analysis: determines the element present in the sample based on the colour of the flame.
    • Quantitative analysis: determines the amount of the element present in the sample based on the intensity of the flame.

    Laminar Flow Burners

    • Also known as Premix burners.
    • Sample, fuel, and oxidant are mixed thoroughly before reaching the burner.
    • Advantages: noiseless, stable flame, efficient atomization of the sample, and steady movement of gas flow.
    • Disadvantages: cannot be used for samples containing two or more solvents.

    Monochromators

    • Prism monochromators: dispersion is non-overlapping, but occurs in a non-linear manner.
    • Grating monochromators: dispersion is linear, but overlapping.

    Detectors

    • Photovoltaic cells: less sensitive than phototubes.
    • Phototubes: more sensitive than photovoltaic cells, used to measure low intensities.

    Applications of Flame Emission Photometers

    • Analysis of biological fluids, such as blood and urine.
    • Determination of sodium and potassium in soil.
    • Determination of metals such as manganese and copper.
    • Analysis of plant materials and industrial cements.

    Chromatography

    • A physical method used to separate and analyze complex mixtures.
    • Stationary phase: solid or liquid supported on a solid.
    • Mobile phase: liquid or gas.
    • Types of chromatography:
      • Column chromatography: stationary phase is solid, mobile phase is liquid.
      • Thin layer chromatography: stationary phase is solid, mobile phase is liquid.
      • Gas chromatography: stationary phase is liquid, mobile phase is gas.
      • Planar chromatography: stationary phase is solid, mobile phase is liquid.
      • Liquid chromatography: stationary phase is solid or liquid, mobile phase is liquid.

    Chromatographic Processes

    • Separation: different components of a mixture separate based on their affinity to the stationary phase.
    • Elution: components elute from the column at different times based on their affinity to the stationary phase.
    • Detection: a detector measures the concentration of the components as they elute from the column.

    Chromatogram

    • A graph obtained by plotting the concentration of the components against time.
    • Used to identify the components of a mixture and their concentrations.
    • The area under the peak is proportional to the concentration of the component.

    Retention Time and Volume

    • Retention time: the time taken by the analyte to reach the detector.
    • Dead time: the time required for a molecule of the mobile phase to pass through the column.
    • Adjusted retention time: the retention time minus the dead time.
    • Retention volume: the volume of mobile phase required to make a solute band move from the point of injection to the detector.
    • Adjusted retention volume: the retention volume minus the dead volume.

    Distribution Constant and Retention Factor

    • Distribution constant: the ratio of moles of solute in the stationary phase to the moles of solute in the mobile phase.
    • Retention factor: the ratio of moles of solute in the stationary phase to the moles of solute in the mobile phase.

    Total Porosity

    • The ratio of interstitial volume of packing to the volume of its total mass.
    • In capillary columns, total porosity is 1.

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