Of course, you only have to add a very small amount. However, when you add a strong dilute acid, for instance, aqueous HCI, the solubility of caffeine in water increases. Hence, caffeine is only moderately soluble in water. By hydrophobic features, I mean, not mixing with water that well. If you take a look at the chemical structure of caffeine, you can see that it consists of two fused rings, imidazole and pyrimidinedione.Īs a result, the hydrophobic features of the structure are quite prominent. Increasing the Solubility of Caffeine in Water
However, there is a saturation point that works as a limitation, especially if the saturation point is crossed.īy a saturation point, I mean the ideal ratio for a mixture of caffeine and water, which is the proper quantity of both components. This will break down the molecules into even smaller fragments allowing it all to blend faster. The process will be even faster if the movement of both the caffeine and water molecules is further enhanced, for example, through rapid stirring. Yes, caffeine can dissolve completely in water if the temperature of the water is high enough. The temperatures for this solubility vary from 32☏ to 59☏.Ĭan Caffeine Dissolve Completely in Water? When it comes to colder temperatures, caffeine’s solubility ranges from 0.6g/100 to 1g/100 ml roughly. Otherwise, people would not have been so fond of iced coffees and such. As time passes, caffeine does dissolve with the cold water. It is apparent that due to the low temperatures of cold water, caffeine will not be that much soluble in cold water. This leads to more collisions between caffeine and water molecules. As a result, the molecules inside hot or boiling water move more rapidly. More temperature means more kinetic energy which will make the particles inside move faster. If you want another example that might be easier for you to grasp, you can take a look at this video.ĭespite being soluble in room temperature water, caffeine’s solubility increases significantly with temperature as mentioned before. All the tests were done six times to check for accuracy and duplication.Īs the results were summarized, they showed that there was an increase in the solubility of caffeine in water which was the result of increases in the temperatures throughout the experiments. Hence, the solid concentration of the sample could be determined. Then it was weighed again to determine the new mass of the remaining solid part. Afterward, it was placed in an oven so that the solvent inside could go through the process of evaporation.Īfter evaporation, the vial was left to dry for nearly 5 hours. The vial was enclosed tightly and then weighed to figure out its mass. The upper portion of the solution was extracted with an appropriate and warm pipette. Then the procedure was repeated with different measurements and temperatures.Īfter the solution had settled after the 2 days, the caffeine which was not dissolved (the excess) could be seen in the lower region of the equilibrium cell. Then, the mixture was heated up in the equilibrium cell to the required temperature, along with continuous stirring.īefore sampling, to maintain the equilibrium, the water, and the undissolved solution were left to settle for exactly 2 days.įor every new measurement, an excess of a known mass of caffeine was included in the known mass of water. The water which was used was re-distilled deionized water.Īs per the gravimetric method, an excess of a known mass of caffeine was added to a known mass of caffeine. With a mass fraction purity that was greater than 98.5%, caffeine was considered soluble.
The data of solubility was then correlated against temperature. Originally, the solubility of caffeine in water was calculated in Germany by a gravimetric method from 298-323K. Measuring the Solubility of Caffeine in Water Both water and caffeine are polar substances.
Additionally, polar substances can dissolve together. The water molecule’s hydrogen is attracted to the highly electronegative oxygen and nitrogen atoms present in caffeine. On its own, caffeine has low solubility.Įven so, Caffeine is soluble in water to an extent as water can hydrogenate with caffeine molecules at six separate places. In its purest form, caffeine exists as a white, odorless, crystalline, or powder-like substance. Conclusion How is Caffeine Soluble in Water?
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