30+ Chemist Interview Questions and Answers for Freshers

Organic chemistry is the study of carbon-based compounds. pH measures acidity or alkalinity. TLC is a technique for separating compounds.

• Organic chemistry focuses on the study of carbon-containing compounds.

• pH is a measure of the acidity or alkalinity of a solution.

• TLC (Thin Layer Chromatography) is a technique used to separate and analyze compounds in a mixture.

• Polar solvents dissolve polar compounds, while non-polar solvents dissolve non-polar compounds.

• 1N HCl (1 Normal hyd...read more

pH is a measure of acidity or alkalinity. Drinking water pH should be around 7. Spectrophotometer measures light absorption. No medical field.

• pH is a measure of the concentration of hydrogen ions in a solution

• Drinking water pH should be around 7, which is considered neutral

• Spectrophotometer operates based on the principle of measuring the absorption of light by a sample

• In my education, I have tested various chemical reactions and performed titrations

• I have operated instrument...read more

pH is a measure of the acidity or alkalinity of a solution. It indicates the concentration of hydrogen ions in the solution.

• pH scale ranges from 0 to 14, with 7 being neutral.

• A pH value below 7 indicates acidity, with lower values being more acidic.

• A pH value above 7 indicates alkalinity, with higher values being more alkaline.

• Each unit change in pH represents a tenfold change in acidity or alkalinity.

• Examples: Lemon juice has a pH of around 2, making it highly acidic. Baking...read more

Normality, molality, and molarity are different ways to express the concentration of a solution.

• Normality is the concentration of a solution expressed in equivalents per liter.

• Molality is the concentration of a solution expressed in moles of solute per kilogram of solvent.

• Molarity is the concentration of a solution expressed in moles of solute per liter of solution.

• Normality is used in acid-base reactions, while molality and molarity are used in general chemistry.

• For example,...read more

The density of H2SO4 and HNO3 varies depending on the concentration.

• The density of H2SO4 and HNO3 can be calculated using the formula: density = mass/volume.

• The density of H2SO4 and HNO3 increases with increasing concentration.

• The density of H2SO4 and HNO3 at standard conditions (concentration of 1 M) is approximately 1.84 g/mL and 1.41 g/mL, respectively.

The molecular weight of H2SO4 is 98.09 g/mol.

• The molecular weight of H2SO4 can be calculated by adding up the atomic weights of its constituent elements.

• H2SO4 consists of 2 hydrogen atoms, 1 sulfur atom, and 4 oxygen atoms.

• The atomic weights of hydrogen, sulfur, and oxygen are 1.008 g/mol, 32.06 g/mol, and 16.00 g/mol respectively.

• Multiplying the atomic weights by the number of atoms and summing them gives the molecular weight of H2SO4 as 98.09 g/mol.

AA is a common abbreviation for amino acids. They have a general structure of NH2-CHR-COOH and can undergo various named reactions like Grignard reaction.

• AA stands for amino acids which are the building blocks of proteins

• Their general structure is NH2-CHR-COOH where R can be any of the 20 different side chains

• Grignard reaction is a named reaction used to form carbon-carbon bonds and is commonly used in organic synthesis

Ethanol and methanol are two common types of alcohol. Ethanol has the formula C2H5OH, while methanol has the formula CH3OH.

• Ethanol formula: C2H5OH

• Methanol formula: CH3OH

Seawage water effluent is the treated wastewater that is discharged into the sea.

• Seawage water effluent is the treated wastewater that is discharged into the sea.

• It is the final product of the sewage treatment process.

• The operation and maintenance of sewage treatment plants ensure that the effluent meets the required standards before discharge.

• Effluent quality is monitored regularly to ensure compliance with environmental regulations.

• Examples of treatment processes include pr...read more

CDCl3 is important in NMR spectroscopy due to its high purity, low cost, and lack of NMR-active protons.

• CDCl3 is commonly used as a solvent in NMR spectroscopy due to its high purity, which minimizes interference with the sample being analyzed.

• CDCl3 is inexpensive and readily available, making it a cost-effective choice for routine NMR experiments.

• CDCl3 does not contain any NMR-active protons, which helps prevent unwanted signals in the NMR spectrum.

• CDCl3 has a high boiling p...read more

Raw materials used in polyester include petroleum, coal, air, and water.

• Polyester is made from a chemical reaction between an acid and an alcohol.

• The acid used is typically terephthalic acid or dimethyl terephthalate.

• The alcohol used is typically ethylene glycol.

• Other raw materials used in the production of polyester include catalysts and stabilizers.

• Polyester production is heavily reliant on petroleum and coal as sources of raw materials.

Viscosity is the measure of a fluid's resistance to flow, density is the mass per unit volume, normality is the concentration of a solution expressed as the number of equivalents per liter, and molality is the concentration of a solution expressed as the number of moles of solute per kilogram of solvent.

• Viscosity is important in determining the flow behavior of fluids, such as in lubrication or mixing processes.

• Density is commonly used in determining the buoyancy of objects i...read more

Various lab instruments are used in chemistry experiments and analysis.

• Spectrophotometer: measures the intensity of light absorbed or emitted by a sample

• Centrifuge: separates substances of different densities using centrifugal force

• pH meter: measures the acidity or alkalinity of a solution

• Bunsen burner: provides a controlled flame for heating substances

• Microscope: magnifies and visualizes small samples

• Gas chromatograph: separates and analyzes components of a mixture

• Balance: m...read more

Sewage waste water network is a system of pipes and treatment plants that collect and treat wastewater from homes and businesses.

• It includes pipes, pumps, and treatment plants that collect and treat wastewater

• The treated water is then released back into the environment or reused for irrigation or other purposes

• The network is designed to prevent the contamination of water sources and protect public health

• Examples of sewage waste water networks include municipal sewer systems a...read more

I have worked as a chemist for 5 years in a pharmaceutical company.

• Developed and validated analytical methods for drug products

• Conducted stability studies to support product shelf-life

• Collaborated with cross-functional teams to troubleshoot manufacturing issues

• Maintained laboratory equipment and ensured compliance with safety regulations

The formula of Benzene is C6H6.

• Benzene is a cyclic hydrocarbon with a ring of six carbon atoms and six hydrogen atoms.

• The molecular formula of Benzene is C6H6.

• Benzene is represented as a hexagon with a circle inside to indicate delocalized electrons.

The formula of sulphuric acid is H2SO4.

• The formula of sulphuric acid consists of hydrogen (H), sulfur (S), and oxygen (O) atoms.

• It is a strong mineral acid with the chemical formula H2SO4.

• Sulphuric acid is commonly used in various industrial processes such as in batteries, fertilizers, and chemical synthesis.

Toluene is a colorless liquid with a benzene ring and a methyl group attached.

• Toluene has a chemical formula of C7H8

• It consists of a benzene ring with a methyl group attached

• The molecular structure of toluene is represented as C6H5CH3

Water testing can be done through various methods to determine its quality and safety for consumption.

• Collect water samples from different sources

• Conduct physical tests to check for color, odor, and turbidity

• Chemical tests can be done to check for pH, dissolved solids, and chlorine levels

• Biological tests can be done to check for the presence of bacteria, viruses, and parasites

• Compare results with established standards and guidelines

• Repeat tests periodically to ensure ongoing ...read more

Normality is a measure of concentration in chemistry, expressed as the number of equivalents of a solute per liter of solution.

• Normality (N) = Number of equivalents / Volume of solution in liters

• It is important to know the valence of the solute to calculate normality accurately

• For example, to find the normality of HCl (hydrochloric acid), which is a monoprotic acid, you would use the formula N = Molarity x 1

• For a diprotic acid like H2SO4, you would use N = Molarity x 2

Sulfuric acid formula is H2SO4.

• Sulfuric acid formula is H2SO4

• It is a strong mineral acid

• Commonly used in various industrial processes such as battery production and metal cleaning

Density of solvents is an important property for various chemical processes.

• Density is the mass per unit volume of a substance.

• Solvents with higher density can dissolve more solutes.

• Density can be affected by temperature and pressure.

• Examples of solvents with different densities include water (1 g/mL), ethanol (0.789 g/mL), and chloroform (1.48 g/mL).

Salt formula refers to the chemical formula of a salt compound, which is typically composed of a metal cation and a non-metal anion.

• Salt formula is written as the combination of the symbols of the elements involved, with the cation listed first followed by the anion.

• For example, the salt formula for sodium chloride is NaCl, where Na represents the sodium cation and Cl represents the chloride anion.

• Common salt formulas include KCl (potassium chloride), CaCO3 (calcium carbonate...read more

GC and HPLC are both analytical techniques used to separate and analyze mixtures of compounds.

• GC separates compounds based on their volatility and boiling points, while HPLC separates compounds based on their polarity and size.

• GC uses a gas as the mobile phase and a solid or liquid stationary phase, while HPLC uses a liquid as the mobile phase and a solid stationary phase.

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

Lyophilization is a process of freeze-drying drugs to increase their shelf life and stability.

• The drug is frozen and then placed in a vacuum chamber where the ice is sublimated

• The process removes water from the drug, making it more stable and less prone to degradation

• Lyophilized drugs can be reconstituted with a solvent before use

• This process is commonly used for vaccines, antibiotics, and other injectable drugs

Iron can be tested using various methods including colorimetry, titration, and atomic absorption spectroscopy.

• Colorimetry involves adding a reagent that reacts with iron to produce a color change, which can be measured using a spectrophotometer.

• Titration involves adding a solution of known concentration to a sample containing iron until the reaction is complete, and then measuring the amount of solution used.

• Atomic absorption spectroscopy involves passing a beam of light thro...read more

Benzene can be converted to benzenol (phenol) by treating it with a mixture of concentrated sulfuric acid and sodium hydroxide.

• Benzene is first treated with concentrated sulfuric acid to form a sulfonic acid intermediate.

• The sulfonic acid intermediate is then treated with sodium hydroxide to form benzenol (phenol).

• The reaction is exothermic and requires careful temperature control.

• The process is known as the Dow process and is widely used in industry to produce phenol.

• The rea...read more

The process of ampoule drug involves filling a sterile solution into a glass ampoule and sealing it.

• The drug solution is prepared and filtered to remove any impurities.

• The glass ampoule is sterilized and dried before filling.

• The drug solution is filled into the ampoule using a filling machine.

• The ampoule is then sealed using a flame or a sealing machine.

• The sealed ampoules are inspected for any defects or leaks.

• The ampoules are labeled and packaged for distribution.

• The proces...read more