WorksheetsChemistry Laboratory Techniques 2
Total questions: 20
Worksheet time: 47mins
What is the term for process in which two immiscible liquids are mixed to transfer any chemical compound of interest from one phase to another?
Filteration
Distillation
Liquid-Liquid Extraction
Decanting
Which of the following statements is FALSE about procedures for Liquid-liquid extraction
Venting of the funnel is necessary to release built up pressure during shaking
The effectiveness of extraction depends on the number of extractions
NaCl is added into the sample if an emulsion is formed to separate the layers
Drying agents are added along with the sample inside the separatory funnel for maximum extraction
Meshya dissolved 0.5g of Compound B in 20 mL of water and poured the solution in a separating funnel. She then added 10 mL of organic solvent, invert and left the mixture to stand for a few minutes. After the extraction, she found out that the distribution coefficient (Kpc) of Compound B between organic solvent / water is 8.33.
Which of the following represents the mass of Compound B that has transferred into the organic solvent?
0.2043 g
0.4023 g
0.2034 g
0.4032 g
Which of the following is the correct formula to calculate the distribution coefficient (Kpc)?
Kpc =
Concentration of solute in organic solvent /
Concentration of solute in water
Kpc =
Concentration of solute in water /
Concentration of solute in organic solvent
Kpc =
Concentration of solute in organic solution /
Concentration of solute in water
Kpc =
Concentration of solute in water /
Concentration of solute in organic solution
Which of the following completes the statement below?
“Inorganic substances dissolves in the ____________layer whereas organic compounds dissolves in the ____________layer.”
inorganic; inorganic
organic; organic
inorganic; organic
organic; inorganic
Which of the following statements is FALSE about Soxhlet extraction
The Soxhlet set-up is designed to perform continuous extraction automatically
Both condensation and evaporation help recirculate the solvent in the Soxhlet set-up
The sample and boiling chips are placed in the round bottom flask fitted with the Soxhlet extractor and condenser
None of the above
What is the purpose of the siphon tube in the Soxhlet extractor?
To ensure the continuous circulation of the solvent through the sample
To contain the sample throughout the extraction
To collect the extracted sample
All the above
Steam distillation is a method of separating liquids immiscible in water and low volatility, at temperatures below their ______________
Melting point
Boiling point
Triple point
Critical point
To avoid the impurities from splashing over the distillate during steam distillation, distillation flask is sometimes attached with a ____________to avoid mixture contaminating the condenser.
Claisen adapter
Still head adapter
Vacuum adapter
Dropping funnel
How is hot water introduced into the steam distillation set-up without the presence of the steam generator?
Claisen funnel
Dropping funnel
Vacuum adapter
Still head adapter
________________is a process which excess amount of standard solution used to react with the analyte is determined by titrating with another standard solution.
Direct titration
Potentiometric titration
Back titration
Complexometric titration
Which of the following is a good reason for doing a back titration procedure?
When the reaction is too slow
When the standard solution is unstable when kept for longer periods
Suitable indicators are unavailable
All of the above
In back titration, what is the role of the second titrant?
To neutralise excess first titrant
To react with the analyte
Increases accuracy of the titration
Establish endpoint of the titration
How many potential sites for dative covalent bond that can be formed by EDTA?
3
4
5
6
Which of the following statements is TRUE about the behaviour of oxalate (ox) in the complex shown?
Oxalate ion is a monodentate ligand
Oxalate ion is a bidentate ligand
Oxalate ion is a tridentate ligand
Oxalate ion is a tetradentate ligand
Which formula is used to calculate for hardness of water when the sample was titrated against EDTA
Examine the metal complex below.
Which of the following statements is TRUE?
There is one ligand that forms six dative covalent bonds with the metal cation
There are three ligands that each form two dative covalent bonds with the metal cation
There are two ligands that each form three dative covalent bonds with the metal cation
None of the above
What is meant by “end point”?
The point at which the amount of acid is sufficient to neutralise all the base
The point at which a substance turns from solid to a liquid
The point at which an indicator changes colour
None of the above
What is meant by “equivalence point”?
The point at which an indicator changes colour
The point at which a substance turns from solid to a liquid
The point at which the amount of acid is sufficient to neutralise all the base
None of the above
The graph above shows which type of acid-base titration?
Strong acid- strong base titration curve
Strong acid-weak base titration curve
Weak acid-strong base titration curve
Weak acid-weak base titration curve
