Calorimetry of Deep Eutectic Solvents
ISEF Category: Chemistry
Ready to Turn This Idea Into a Real Project?
This guide was put together with the help of AI research tools to give you a solid starting point. But a competitive science fair project lives in the details: refining your research question, fine-tuning your variables, analyzing your data, and presenting your findings like a seasoned scientist.
For next steps tailored to your interests, skill level, and timeline, work one-on-one with a MehtA+ mentor. Learn more about MehtA+ Science & Engineering Research Mentorship →
Subcategory: Physical Chemistry · Difficulty: Intermediate · Setup: School Lab · Time: 1 to 2 Months
The Hook
Some liquids are not really one substance at all. They are mixtures that act like a new material. Deep eutectic solvents can behave like ionic liquids, but they are often easier and cheaper to make. That makes them a smart target for a student project that connects chemistry, data collection, and prediction.
What Is It?
Heat-of-solution calorimetry measures how much heat a substance releases or absorbs when it dissolves. Think of it like checking whether a mixture gives off a tiny burst of warmth or a tiny chill. Your foam cup acts like a simple heat shield, and your thermistor tracks the temperature change. The bigger the temperature shift, the bigger the energy change.
Deep eutectic solvents are mixtures of two or more compounds that melt at a much lower temperature than either component alone. A common pair is choline chloride and urea. Other versions use glycerol or sugar donors. In plain language, the ingredients fit together in a way that changes how strongly they hold onto each other. That makes them interesting for comparing real calorimetry data with predicted enthalpies from COSMO-style models, which estimate how molecules should interact based on their surface charge patterns.
Why This Is a Good Topic
This topic works well because you can change one mixture at a time and measure a number you can actually compare. You are not just making a pretty reaction. You are testing how different deep eutectic solvent recipes behave, and whether a model predicts those changes well. That gives you real chemistry, real data, and a clear reason your results matter for green solvents, extraction, and materials design.
Research Questions
- How does the hydrogen-bond donor change the heat of solution of choline chloride deep eutectic solvents?
- What is the effect of donor-to-acceptor ratio on measured enthalpy in choline chloride mixtures?
- Does the measured heat of solution match the COSMO-style predicted enthalpy ranking across solvent recipes?
- To what extent does water content change the calorimetric signal for deep eutectic solvent samples?
- Which deep eutectic solvent formulation gives the largest temperature change per gram dissolved?
- How does the choice of donor, such as urea, glycerol, or sugar, affect the sign and size of the enthalpy change?
Basic Materials
- Foam cups with lids, or a nested-cup calorimeter setup.
- Digital thermistor probe or temperature sensor.
- Arduino board with USB cable.
- Precision balance with 0.01 g or better resolution.
- Choline chloride.
- Urea, glycerol, or table sugar as hydrogen-bond donors.
- Distilled water.
- Stirring rod or small magnetic stirrer.
- Graduated cylinder or pipettes.
- Lab notebook for recording mass, temperature, and time.
Advanced Materials
- Coffee-cup calorimeter with better insulation insert.
- Calibrated thermistor or digital temperature probe with data logger.
- Arduino, breadboard, jumper wires, and resistor set.
- Magnetic stir plate and stir bars.
- Analytical balance with 0.001 g resolution.
- Choline chloride of known purity.
- Urea, glycerol, glucose, or other donor candidates.
- Drying oven or desiccator for moisture control.
- Access to COSMO-RS or another molecular prediction workflow through school, university, or open literature calculations.
- pH meter or water activity meter if available for side-study checks.
Software & Tools
- Arduino IDE: Lets you collect temperature data from the thermistor and time-stamp each reading.
- Excel: Helps you graph temperature curves, calculate slopes, and compare mixtures.
- Google Sheets: Gives you a free way to clean data, make plots, and share results.
- ImageJ: Can help if you need to extract numbers from plotted figures or screenshots.
- Python: Lets you fit curves, calculate uncertainty, and test how well predictions match measurements.
Experiment Steps
- Define the solvent pairs you will compare and decide which variable changes first.
- Build a simple calorimeter plan that keeps heat loss low and temperature readings consistent.
- Design a data table that captures mass, starting temperature, peak change, and repeat trials.
- Plan a comparison between measured enthalpy trends and predicted enthalpy rankings from a literature model.
- Choose controls that separate composition effects from water content and sensor drift.
- Decide how you will repeat each sample enough times to check precision and uncertainty.
Common Pitfalls
- Letting moisture from the air change the composition of hygroscopic salts and donor powders between trials.
- Using a cup setup that leaks heat too quickly, which flattens the temperature change and hides real differences.
- Recording the peak temperature too late, which makes exothermic and endothermic samples look closer than they are.
- Comparing samples with different mixing histories, which changes the apparent enthalpy before the run even starts.
- Ignoring how concentration and mass ratio affect the result, which can make a model comparison meaningless.
What Makes This Competitive
A strong project does more than compare a few mixtures. You need careful controls, repeated trials, and a clean way to correct for heat loss. You can also raise the level by testing whether prediction models match your measurements across several donor types, not just one. If you add uncertainty analysis and a clear explanation for mismatches, your project starts to look like real physical chemistry.
Project Variations
- Compare choline chloride with different hydrogen-bond donors, such as urea, glycerol, and glucose, to see which pairing shifts enthalpy the most.
- Test how added water changes the heat of solution, then see whether the prediction error grows as the mixture gets wetter.
- Use a smartphone camera or IR thermometer alongside the thermistor to compare whether two measurement methods give the same calorimetry trend.
Learn More
- PubMed: Search for review articles on deep eutectic solvents, thermodynamics, and calorimetry to find background and related experiments.
- NIH PubChem: Look up choline chloride, urea, glycerol, and glucose for structure, properties, and safety summaries.
- NIST Chemistry WebBook: Search for thermodynamic data and property references that can help you sanity-check values.
- MIT OpenCourseWare: Find physical chemistry lecture notes on thermodynamics and solution energetics.
- Journal of Chemical & Engineering Data: Search for measured enthalpy and property papers on deep eutectic solvents.
- Physical Chemistry Chemical Physics: Search for review and research articles on solvent modeling and COSMO-based prediction methods.