Morever, for measuring the density using hydrometer large sample volume is required. Conclusion In conclusion, almost our group reached main target. We used two different methods which were hydrometer and density bottle method in order to measure the density of water at different temperatures. We calculated the densities of water which were 995, 992.5, 991, 990 kg/m3 for the first part and 967 kg/m3 for the second part. Finally we compared these two methods in order to decide which method is more suitable.
Synthesis of ethyl levulinate carried out on the catalytic surface of the composite HEC membrane. A separation layer of composite HEC membrane is capable of selectively permeating water, because HEC is well known hydrophilic polymer. Reaction and separation mechanism of catalytic composite HEC membrane can be explained as follows. Levulinic acid and ethanol were fed at the top of the membrane. Reactants are converted to products in the catalytic surface of the membrane.
In addition, phenolphthalein was added as an indicator. The aliquots were titrated against sodium hydroxide (NaOH) solution until end point was reached, after which volume of NaOH consumed was recorded. The value of the rate constant, k, obtained was 0.0002 s-1. The experiment was then repeated with 40/60 V/V isopropanol/water mixture and a larger value of k = 0.0007 s-1 was obtained. We concluded that the rate of hydrolysis of (CH3)3CCl is directly proportional to water content in the solvent mixture.
Title: Diffusion & Osmosis Purpose: The purpose of this experiment was to test the tonicity of the different solutions. Background: Diffusion and osmosis are both processes that occur within the plasma membrane. Diffusion is the process by which molecules intermingle as a result of kinetic energy. Osmosis is the movement of water across a semi-permeable membrane. Tonicity is also related to osmosis.
Water will act as initial solvent for caffeine extraction. This is due to water that slowly soluble with caffeine at ambient temperature but highly soluble when temperature is at 100°C. Then, methylene chloride is chosen as the extraction solvent, due to its miscibility with caffeine and immiscibility with water. As mentioned above, the immiscible pair is chose for the extraction part because to allow the aqueous and organic layers to be separated. Basically, the bottom layer is the aqueous layer while the upper layer is the organic compound.
The contact angle of the film was measured with distilled water under room temperature. 2.10 Crosslink density () and average molecular weight between two crosslinks (Mc) Crosslink density () and average molecular weight between two crosslinks (Mc) were determined by the equilibrium swelling method according to the Flory-Rehner equation (Eq. 1). Toluene was chosen as a solvent for the calculations. Mc =-(ƥpVsØ1/3)/(ln(1-Ø)+ Ø+ƛØ2) (1) where Vs is the molar volume of the solvent, ƥp is the density of the polymer and Ø is the volume fraction of the polymer in the swollen state.
Osmosis and diffusion have similar concepts but have their own individual processes. Osmosis is the process in which there is transport of a solvent through a semipermeable membrane that separates two solutions of contrasting solute concentration. During osmosis, the solvent moves from the solution that is lower in concentration of solute to the solution that is higher in concentration of solute, eventually reaching an equilibrium (Johnston). Diffusion is the movement of matter from one point to another by random molecular motions. The rate of diffusion of a substance is proportional to the concentration gradient of that substance (Leaist).
Introduction Chromatography is the technique of separating of mixtures based on their intermolecular forces. It separates according to their adsorption differences. Intermolecular forces make molecules bind on the solid surfaces; this process is referred to as the absorption. A molecule undergoes desorption process when it moves from the solid surface into the solution. The different rates between desorption and adsorption are applied in the chromatography methods for separation of mixtures.
Conclusion It was clearly observed that the decrease in the concentration of hydrogen peroxide lead to increase in the reaction time and also decrease in the rate of the reaction. Also the decrease on the concentration decreases the rate of the reaction. The two graphs were straight line graphs with positive slopes. So effective collision for a chemical reaction depends directly on the concentration of the reagent, that is, the crowdedness of the reacting molecules which increases reaction time and vice versa. References
The solubility of a substance fundamentally depends on the solvent used as well as on temperature and pressure. The extent of solubility of a substance in a specific solvent is measured as the saturation concentration where adding more solute does not increase its concentration in the solution . IUPAC defines solubility as the analytical composition of a saturated solution expressed as a proportion of a designated solute in a designated solvent. Solubility may be stated in units of concentration, molality, mole fraction, mole ratio, and other units