The Top 22 Chemistry Interview Questions You Need to Know in 2024

Getting hired as a chemist takes more than just having a degree in chemistry You need to demonstrate your knowledge, skills, and abilities during the interview process Chemistry interviews will test your grasp of chemical concepts and lab techniques, as well as assess your problem-solving abilities, communication skills, and more.

To help you prepare for your next chemistry interview. here are the top 22 chemistry interview questions you should expect in 2024 with example answers

Technical Questions

1. Explain the term aliquot and diluent?

   An aliquot is a measured portion of a solution taken for analysis. A diluent is a substance that dilutes or thins out a solution. For example, an analyst may take a 5 mL aliquot of a concentrated acid solution and add it to 45 mL of water as the diluent to prepare a diluted sample for testing.

2. What is molality?

   Molality is a measurement of the concentration of a solution expressed as the number of moles of solute per kilogram of solvent. It differs from molarity which expresses concentration as moles of solute per liter of solution. Molality is useful for solutions where the solvent’s density can change due to temperature fluctuations.

3. What is titration?

   Titration is a quantitative chemical analysis method used to determine the concentration of a dissolved substance. It involves slowly adding a reagent of known concentration (titrant) to a solution of unknown concentration until the chemical reaction between them is complete, as indicated by a color change or other indicator. The volume of titrant required to reach the endpoint allows calculation of the analyte concentration.

4. What is a buffer?

   A buffer is a solution containing a weak acid and its conjugate base that resists changes in pH when small amounts of acid or base are added. Buffers minimizepH changes by neutralizing added acids/bases via the buffering components rather than water. This makes them useful for keeping the pH stable in lab reagents and biological systems.

5. How does a buffer work?

   A buffer works by having a reservoir of weak acid and base that can replenish one another. For example, in an acetate buffer, acetic acid and acetate ion coexist in equilibrium. If hydroxide ion is added, acetate ion accepts the proton to reform acetic acid and minimize the pH change. If hydronium ion is added, acetic acid gives up a proton to acetate ion.

6. What is a mole?

   A mole is a standard scientific unit equivalent to 6.022 x 10^23 molecular units of a substance. Put simply, a mole represents a certain number of atoms, molecules, ions, or other entities. For example, 1 mole of carbon atoms would contain 6.022 x 10^23 carbon atoms. Moles allow chemists to relate atomic/molecular masses to macroscopic masses.

7. How will you calculate how many moles of glucose present in 320 mL of 5.0 M glucose solution?

   • The molarity (M) of glucose solution is 5.0 M
   • Molarity = moles solute/Liters solution
   • Volume of solution given = 320 mL = 0.32 Liters
   • Use Molarity equation to find moles of glucose:
     • Moles = Molarity x Volume in Liters
     • Moles of glucose = 5.0 M x 0.32 L = 1.6 moles

Behavioral Questions

1. Tell me about a time you made a mistake in your research. What did you do to address the issue?

   • Admit you recorded data incorrectly during important experiment
   • Realized the mistake when data did not support hypothesis
   • Took responsibility and informed supervisor immediately
   • Repeated experiment using careful notes to get accurate data
   • Learned to double check data entry and calculations

2. Describe a situation when you disagreed with the findings of a colleague. Did you confront them?

   • Noticed colleague’s conclusions did not match raw data
   • Respectfully pointed out discrepancies during team meeting
   • Allowed colleague to explain methodology and reasoning
   • Discussed possible sources of errors with colleague and supervisor
   • Agreed to re-test hypothesis using revised methods
   • Maintained open communication to resolve issue amicably

3. Unpack a time when you succeeded under significant pressure while performing chemistry work.

   • Asked to develop new polymer under tight deadline for important client
   • Felt overwhelmed balancing multiple projects
   • Broke down project into smaller milestones and prioritized most critical steps
   • Asked mentor for advice and techniques for staying focused
   • Maximized productivity by meticulously planning days in advance
   • Met tight deadline by managing time effectively under pressure

Soft Skills Questions

1. What qualities do you look for in a workplace environment?

   • Collaborative team culture where ideas are freely shared
   • Access to mentorship from experienced chemists
   • Emphasis on scientific ethics and safety
   • Resources to continuously advance skills and knowledge
   • Leadership that supports growth opportunities
   • Open communication and transparency

2. How do you handle disagreements in the workplace?

   • Remain professional, calm, and logically explain my perspective
   • Actively listen to the other person’s viewpoint without judgment
   • Find common ground and validate any valid points the other party has
   • If needed, politely agree to disagree and escalate issue to manager
   • Focus on resolving the conflict quickly and respectfully
   • Follow-up to check the relationship is still positive afterward

3. How do you adapt to major workplace changes?

   • Roll with the punches and keep an open mind to change
   • Ask questions to deeply understand reasons for and goals of change
   • Communicate concerns constructively but stay solutions-oriented
   • Break down personal action plan aligned with new procedures
   • Embrace change as an opportunity to advance skills and grow
   • Remain composed under uncertainty and support teammates

Technical Skills Questions

1. How would you prepare a 250 milliliter acetone stock solution at 2 molar concentration?

   • Convert desired concentration (2M) to moles per liter (2M = 2 moles/L)
   • Calculate required moles of solute using molarity equation:
     • Moles = Molarity x Volume in Liters
     • Moles of acetone required = 2 moles/L x 0.25 L = 0.5 moles
   • Use moles and molar mass (58 g/mole for acetone) to calculate required mass:
     • Mass = Moles x Molar mass
     • Mass of acetone = 0.5 moles x 58 g/mole = 29 grams
   • Weigh 29 grams acetone using analytical balance
   • Transfer to 250 mL volumetric flask
   • Dilute to mark with solvent to prepare 2 molar acetone stock solution

2. How would you prepare 100 milliliters of 0.1 molar hydrochloric acid from a 6 molar HCl stock solution?

   • Convert desired molarity to moles using molarity equation:
     • Molarity = moles/Liters
     • 0.1 M = 0.1 moles/L
   • Multiply moles by desired volume to get moles needed:
     • 0.1 moles/L x 0.1 L = 0.01 moles HCl
   • Convert moles of HCl to volume of stock solution:
     • Stock is 6 M so 6 moles HCl per 1 L
     • Use ratio to convert moles to volume of stock
     • 0.01 moles HCl x (1 L stock/6 moles HCl) = 0.0017 L = 1.7 mL
   • Measure 1.7 mL of 6 M HCl stock using volumetric pipette
   • Transfer to volumetric flask and dilute to 100 mL final volume with water

3. Describe how to prepare a buffer solution from a weak acid and its salt.

   • Determine target pH and acid dissociation constant (Ka)
   • Select a weak acid and its salt to buffer at desired pH
   • Calculate buffering capacity needed for application
   • Determine ratios of salt and acid from Ka and buffering capacity
   • Weigh appropriate amounts of acid and conjugate base
   • Dissolve in solvent and adjust to final desired volume
   • Verify pH of buffer solution using pH meter
   • Adjust ratio if needed to achieve target pH

4. How would you test if an unknown liquid is water, ethanol, or acetone?

   • Determine physical properties like appearance, odor, density, boiling point
   • Test flammability – ethanol and acetone should combust, water won’t
   • Add anhydrous copper sulfate powder – water will cause color change
   • Use IR spectroscopy or Raman spectroscopy to identify functional groups
   • Run sample through gas chromatograph to separate components
   • Compare retention times to those of known standards

5. Describe the titration process and how you would determine when the endpoint is reached.

   • Prepare analyte solution of known approximate concentration
   • Select suitable titrant and indicator for reaction
   • Standardize titrant by titrating substance of known purity
   • Clean and fill buret with titrant solution
   • Add indicator to analyte solution
   • Slowly add titrant to analyte while swirling and observing color change
   • The endpoint is reached when indicator color change persists for ~30 seconds
   • Record volume of titrant used

6. **How would you prepare a pharmaceutical capsule containing 50 milligrams of