The heat obtained when a known mass of alcohol or paraffin wax burns will be used to warm a measured volume of water. Enthalpy change can be defined as the amount of heat released or absorbed when a chemical reaction occurs at constant pressure. In an exothermic reaction, such as the case in this experiment, the following reaction takes place: H = H(products) - H(reactants) = negative (-ve) Specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius. The relationship between heat and temperature change is usually expressed, where c is the specific heat. The relationship does not apply if a phase change is encountered, because heat added or removed during a phase change does not change the temperature.
Distillation is used to purify a compound by separating it from a non-volatile or less-volatile material. When different compounds in a mixture have different boiling points, they separate into individual components when the mixture is carefully distilled. The boiling point is the temperature at which the vapor pressure of the liquid phase of a compound equals the external pressure acting on the surface of the liquid. The external pressure is usually the atmospheric pressure. Different compounds boil at different temperatures because each has a different, characteristic vapor pressure: compounds with higher vapor pressures will boil at lower temperatures.
By using this method of distillation a mixture is heated to a temperature at which several fractions of the compound is evaporated the distillate is then condensed and collected. Generally the component parts have boiling points that differ by as little as 20-30°C under a pressure of one atmosphere. However, cyclohexene and cyclohexanol have boiling points of 83°C and 161°C, respectively, and fractional distillation was used to separate the starting material from the desired product. The mixture is heated and boiled and the vapors produced are condensed and the distillate is collected and then tested by GC analysis. The Agilent 7890A Gas Chromatography System separates chemicals based on the ease with which they evaporate into a gas, also known as the volatility.
The change in enthalpy relies on the concentration of the salt solution, because different concentrations will produce different enthalpies. There is an equation to determine how much of this heat energy is lost or gained when a reaction is performed. Q = c m (T1-T2) Where: q is the energy in Joules C is the heat capacity, measured in joules per gram per degree Celsius M is the mass of the solution, measured in grams J is the joules G is the grams of water T is the temperature ΔH=ΔE + PΔV = (q p +w) – w = q p Procedure: 1. Follow instructions 1-9 in Appendix A-1 to initialize the MeasureNet workstation. a.
The simple addition of water to FeSO4 will not lead to the formation of FeSO4•7H2O. Determination of the number of molecules of water in a hydrate. If you do not know how many molecules of water are in one molecule of hydrate and want to find this out, it can be done by measuring the masses of the hydrate and anhydrous compound formed after the heating. For example, let’s assume that we do not know how many water molecules are attached to BaCl2. Let’s call this number X.
Observe the color change while it is being heated. After observing the color change, find the mass and moles of the hydrate. Then find the mass and moles of the water eliminated. And lastly find the mole ratio of water to hydrate. For part 2, do the same thing as part 1 except use an unknown hydrate and calculate the percent mass of water in an unknown hydrate.
At this point the can will collapse. Alternatively, the same concept can be demonstrated by adding water to an Erlenmeyer flask, heating the water to a boil and quickly placing a balloon over the mouth of the flask. When the flask is then submerged in ice water the balloon collapses inside the flask. Beaker Bunsen burner Discussion: Boyle’s Law describes the relationship between volume and pressure of gases. The volume of a gas varies inversely with
Discussion & Conclusion In this experiment we learned how to synthesize the cyclohexene by dehydration of cyclohexanol. We procedure the first step where we have to mix the components. Then we heat the R.B.F with a fractionating column, distilled water. Then we obtained the layers, and we transferred the organic layer to a small, dry Erlenmeyer flask. We added anhydrous Sodium Sulfate as a drying agent.
1A-Water/MSG: When shaken the water and MSG they mostly dissolve creating an orange gold color, the substance foams at the top from the vigorous shaking action yet still some MSG residue remains at the bottom of the test tube, it was unclear if the reason was because we did not mix it enough or rather we added too much MSG to the amount of water given. 1A-Alcahol/MSG: These two substances barely mix together leaving a transparent yellow tint to the alcohol as well as MSG that was unable to dissolve at the bottom of the test tube. We concluded that this residue was unable to be dissolved in this liquid because the amount of MSG remaining in the bottom of the test tube was around the same amount that was originally placed into the alcohol. 1B- Alcohol/Vegetable Oil: Created a foamy top layer, was semi unclear but as to the best of my observations the alcohol nearly completely dissolved the oil, leaving a foggy appearance to the once clear
Chemical Equilibrium – Solubility The solubility of a substance is dependent on the forces holding the crystal together (the lattice energy) and the solvent acting on these forces. For now, we will consider only water as the solvent. As the solid dissolves, water molecules surround the ions in the solution by a process called hydration. During hydration, energy is released. The extent to which the energy of hydration is greater than the lattice energy determines the solubility.