n (3) Solutions of aqueous sodium hydroxide and hydrochloric acid react to form water and aqueous sodium chloride. co NaOH(s) → Na+(aq) + OH–(aq) ∆H1 = ? Chemistry with Vernier py In this experiment, you will use a Styrofoam-cup calorimeter to measure the heat released by three reactions. One of the reactions is the same as the combination of the other two reactions. Therefore, according to Hess’s law, the heat of reaction of the one reaction should be equal to the sum of the heats of reaction for the other two.
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.
Since boiling point and vapor pressure are inversely proportional, the separation is thus based on the vapor pressure as well. In order for the distillation to be effective, the components of the solution must have significantly different boiling points, preferably between 30-40℃. In this experiment, hexane has a boiling point of 69℃, while toluene has a boiling point of 111℃. A liquid is heated to its boiling point and the vapors generated are condensed by cooling and collected in a receiving vessel. One vaporization and condensation cycle is called a theoretical plate.
Objective: The objective of the first lab is to use the graph of Pressure versus Temperature to estimate the value of Absolute Zero. Based on the Gay-Lussac’s Law, pressure is proportional to temperature; we are able to find the Absolute Zero when the pressure reaches zero. Conclusion: Our experimental result is -285.40 C. It means when pressure reaches zero, the temperature should reach -273.15 C, which is the value of Absolute Zero. Our experimental Absolute Zero value is fairly close to the accepted value, and the percentage error is 4.48%. One of the major sources of error in this experiment is that the volume of metal ball will rise while the surrounding water’s temperature rise.
The atmospheric pressure from the barometer was also recorded. Results: Atmospheric Pressure = 766.20 mmhg = 1.02 bar Absolute Pressure (bar) T1(heating) (oC) T2(cooling)( oC) +1.0/-1.0 +1.0/-1.0 2.02 116 120 3.02 129 134 4.02 140 144 5.02 149 154 6.02 157 161 7.02 163 167 8.02 168 173 9.02 174 177 Precautions: • Readings from the barometer and the thermometer were read at eye level, to avoid parallel errors. • The thermometer pocket was filled with oil to increase thermal conductivity. • The marcet boiler was not touched with bare hands since it could be hot. Conclusion The results from the first reading while heating to the second reading while cooling varied slightly due to human errors and random errors.
2. Explain what relationship exists between the pressure and volume of a gas (assuming a constant temperature), based on your collected data. Answer: The relationship between Pressure and Volume is inversely proportional. As one decrease, the other increases. P1V1=P2V2 3.
Measurement of Heat Capacity Ratio and Speed of Sound in Gases Experiment 1 September 12, 2013 Physical Chemistry Laboratory Abstract The speed of sound in gases will be studied by two types of tests on four gases: argon, carbon dioxide, helium, and dry air. The two tests that will be used on different settings on an oscilloscope are: the X-Y mode and internal time base mode. The gases will be filtered through a tube that is connected to an acoustical tube with a microphone and earpiece. The different waves will be displayed through a screen on the oscilloscope where the wavelength can be determined by studying the different patterns. Once the wavelength is calculated, the heat capacity ratio for each of the gases will be calculated.
What did Boyle’s experiments convince him about cold? That heat is a form of motion of a particular kind as bodies cool down the particles move less and less 5. How did Boyle explain that substances expand when they warm up? He thought back to his air experiments, and explained that the particles have spring like coils that expand as they heat 6. Describe the earliest alcohol thermometers.
The mobile phase used in this particular experiment was Methanol and 0.1M sodium dihydrogen phosphate at a ratio of 30:70 and a pH of 4.5, slightly acidic. The stationary phase is the silica based particles packed within the column. The key characteristic of HPLC is the sheer pressure it works under. In fact HPLC is often referred to as high pressure liquid chromatography. The pressure at which the machine used in this investigation works is around 1900psi (pounds per square inch) which is the equivalent of 129.29 atmospheres!