20+ Quality Control Chemist QC Chemist Interview Questions and Answers

Answers to questions related to QC Chemist role including formation of phenyl, full forms of MCP and LCO, dispersion and emulsion of phenyl, and minimum qualifications for drug license and pesticide formulation.

• Phenyl is formed by the reaction of benzene with a halogen or nitric acid.

• MCP stands for Monochlorophenol.

• LCO stands for Light Cycle Oil.

• Dispersion of phenyl refers to the even distribution of its particles in a solvent.

• Emulsion of phenyl refers to the mixture of oil a...read more

To calculate the CaO% in limestone with 95.00% CaCO3, multiply the CaCO3 percentage by 0.56.

• CaO% = CaCO3% x 0.56

• CaO% = 95.00% x 0.56

• CaO% = 53.20%

Internal and external standards are used in quality control to ensure accurate and reliable measurements.

• Internal standard is a substance that is added to the sample being analyzed, which is used as a reference to measure the analyte of interest.

• External standard is a separate sample with a known concentration of the analyte, which is used to calibrate the instrument and validate the accuracy of the measurements.

• Internal standards help correct for variations in sample prepara...read more

The molecular weight of hydrated lime and quicklime varies depending on the specific compound.

• Hydrated lime, also known as calcium hydroxide (Ca(OH)2), has a molecular weight of approximately 74.09 g/mol.

• Quicklime, also known as calcium oxide (CaO), has a molecular weight of approximately 56.08 g/mol.

• The molecular weight of these compounds is important in quality control as it helps determine the concentration and purity of the substances.

• Knowing the molecular weight allows f...read more

The raw materials used in making slaked lime are limestone and water.

• Limestone is the main raw material used in making slaked lime.

• Water is added to limestone to produce slaked lime through a chemical reaction.

• Other impurities in the limestone may affect the quality of the slaked lime.

Lab chemical apparatus includes equipment used for chemical analysis and experimentation. Plating is the process of coating a metal with another metal.

• Common lab apparatus includes beakers, flasks, pipettes, burettes, and spectrophotometers.

• Plating can be done using electroplating, electroless plating, or immersion plating.

• Electroplating involves passing an electric current through a solution containing ions of the metal to be plated onto the object.

• Electroless plating uses a...read more

Primary standards are highly pure compounds used for calibration, while secondary standards are less pure and used for routine analysis.

• Primary standards are used to calibrate instruments and determine the accuracy of measurements.

• They are highly pure and stable compounds that can be weighed accurately.

• Examples of primary standards include potassium hydrogen phthalate and sodium carbonate.

• Secondary standards are used for routine analysis and are less pure than primary standar...read more

A pH buffer is a solution that resists changes in pH when small amounts of acid or base are added.

• pH buffers are composed of a weak acid and its conjugate base or a weak base and its conjugate acid.

• They maintain a stable pH by neutralizing added acid or base.

• Common examples of pH buffers include phosphate buffer, acetate buffer, and Tris buffer.

Resolution is the ability to distinguish between two closely spaced objects or the ability to distinguish between two closely spaced peaks in a chromatogram.

• Resolution is a measure of the clarity or sharpness of an image or signal.

• It is commonly used in microscopy, spectroscopy, and chromatography.

• Resolution is determined by factors such as the wavelength of light or radiation used, the numerical aperture of the lens, and the size of the detector.

• In microscopy, resolution ref...read more

GC and HPLC are both analytical techniques used to separate and analyze compounds, but they differ in their principles and applications.

• GC separates compounds based on their volatility and affinity for the stationary phase, while HPLC separates compounds based on their polarity and affinity for the mobile and stationary phases.

• GC is typically used for volatile and semi-volatile compounds, while HPLC is used for non-volatile and polar compounds.

• GC requires a gaseous mobile pha...read more

Instruments are calibrated by comparing their readings to a known standard and adjusting them accordingly.

• Identify the standard to be used for calibration

• Ensure the instrument is clean and free of debris

• Record the initial readings of the instrument

• Compare the readings to the standard and adjust as necessary

• Record the final readings and document the calibration process

To prepare a solution, measure the required amount of solute and dissolve it in the appropriate amount of solvent.

• Determine the concentration and volume of the desired solution

• Measure the required amount of solute using a balance

• Add the solute to a volumetric flask or beaker

• Add the appropriate amount of solvent to reach the desired volume

• Stir the solution until the solute is completely dissolved

Tailing factor is a measure of peak asymmetry in chromatography, indicating the presence of tailing or fronting.

• Tailing factor is calculated by dividing the distance from the peak apex to the leading edge of the peak by the distance from the peak apex to the trailing edge of the peak.

• A tailing factor of 1 indicates a symmetrical peak, while values greater than 1 indicate tailing and values less than 1 indicate fronting.

• Tailing can be caused by various factors such as column o...read more

Water is used in KF factor to ensure accurate measurement of water content in a sample.

• KF factor is a calibration factor used in Karl Fischer titration to determine water content in a sample.

• Water is added to the KF reagent to ensure that all the water in the sample is reacted with the reagent.

• The amount of water added to the KF reagent is used to calculate the KF factor.

• The KF factor is then used to calculate the water content in the sample.

• Using water in KF factor helps to ...read more

Polar and nonpolar are terms used to describe the distribution of electrons in a molecule.

• Polar molecules have an uneven distribution of electrons, resulting in a partial positive and partial negative charge.

• Nonpolar molecules have an even distribution of electrons, resulting in no partial charges.

• Examples of polar molecules include water and ammonia, while examples of nonpolar molecules include oil and methane.

Theoretical plate is a hypothetical zone in a chromatographic column where separation of components occurs.

• Theoretical plate is a concept used in chromatography to describe the efficiency of a column.

• It is a hypothetical zone in the column where separation of components occurs.

• It is used to calculate the number of plates in a column.

• The more theoretical plates a column has, the better the separation of components.

• Theoretical plates are calculated using the Van Deemter equatio...read more

Testing of silica in clinker involves determining the amount of silica present in the clinker sample.

• Silica in clinker is typically measured using X-ray fluorescence (XRF) analysis.

• The clinker sample is prepared by grinding it into a fine powder and then mixing it with a binder.

• The prepared sample is then analyzed using an XRF instrument, which measures the intensity of X-rays emitted by the sample.

• The intensity of the X-rays is proportional to the amount of silica present in...read more

The question is incomplete and lacks context. Please provide more information.

• What is the context of the calculation?

• What does 'rs' stand for?

• What is the significance of the 5% value?

• What units are being used?

• What formula was used to calculate the 5% rs?