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Essay about intermolecular forces
A term paper on intermolecular forces
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Evaporation and Intermolecular Forces Lab
Analysis Questions:
Pentane was observed to have the highest evaporation rate. Isopropanol had the lowest evaporation rate. Pentane is nonpolar and it’s strongest intermolecular force is London Dispersion Force. Because Isopropanol is polar and has strong hydrogen bonds, the bonds are harder to break and the evaporation rate was lower because it took more time to break this force. Pentane has a weaker molecular force than the hydrogen bonds so it evaporated faster than the Isopropanol. Every time the container the substance is in is opened some of it will evaporate, causing the temperature of the liquid to change. As it evaporates, the temperature decreases. The molar mass of a substance can be
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The evaporation rate for Isopropanol for my group was -0.10913 degrees Celsius per second and the average for the class was -0.11 degrees Celsius per second. For Acetone we got -0.2244 degrees Celsius per second, and the class average was -0.30 degrees Celsius per second. The rate for Hexane we got was -0.17307 degrees Celsius per second, and the class average was -0.13 degrees Celsius per second. The evaporation rate for Pentane was -0.35389 degrees Celsius, while the class average was -0.47 degrees Celsius per second. Pentane had the highest evaporation rate and and Isopropanol had the lowest. This is because Isopropanol is polar and has strong hydrogen bonds that are harder to break than the weak London Dispersion Force in the nonpolar Pentane. Isopropanol took more time to break the bonds, causing a slower evaporation rate than the evaporation rate of Pentane. Pentane evaporated the fastest out of all of the substances because its bonds were so weak. Hexane and Pentane have London Dispersion Force as their strongest intermolecular force, but Hexane has a higher molar mass than Pentane. In the data, it is shown that Hexane has a slower evaporation rate the Pentane, meaning that the intermolecular forces in Hexane are stronger than
Thermodynamics is essentially how heat energy transfers from one substance to another. In “Joe Science vs. the Water Heater,” the temperature of water in a water heater must be found without measuring the water directly from the water heater. This problem was translated to the lab by providing heated water, fish bowl thermometers, styrofoam cups, and all other instruments found in the lab. The thermometer only reaches 45 degrees celsius; therefore, thermodynamic equations need to be applied in order to find the original temperature of the hot water. We also had access to deionized water that was approximately room temperature.
At a constant temperature, a pure liquid has a vapor pressure that describes the pressure of escaped gaseous molecules that exist in equilibrium at the liquid’s surface. Adding energy to a pure liquid gives more molecules the kinetic energy to break the intermolecular forces maintaining the liquid and raises the overall temperature of the liquid. Eventually, adding energy boosts the liquid’s vapor pressure until it equals the surrounding atmospheric pressure. When this occurs, the pure liquid boils at a temperature called the boiling point.
Olefin/paraffin separation is very difficult to achieve because the molecules are similar in size and volatility. The relative volatility of propylene and propane mixture is 1.1 and that of ethylene and ethane is 1.5. Traditional
When there is a heat exchange between two objects, the object’s temperature will change. The rate at which this change will occur happens according to Newton’s Law of heating and cooling. This law states the rate of temperature change is directly proportional between the two objects. The data in this lab will exhibit that an object will stay in a state of temperature equilibrium, unless the object comes in contact with another object of a different temperature. Newton’s Law of Heat and Cooling can be understood by using this formula:
enclosure is driven by the strength of the hydrogen bonds between the water molecules, leading
The freezing point of p-xylene was calculated by taking the average calculated Kf of the three trials of the p-xylene and toluene solution. The average of the three trials was computed as 4.56(C/m) as shown in Table 1, however, the theoretical value was slightly lower than calculated, 4.3(C/m). This resulted in a 6.04% error as shown in Equation 5; possible causes of error could have resulted from adding too much solute or too little solvent, then the calculations would have been off given that the solution was not dilute enough. Having too much solvent could be attributed to having a higher Kf than the theoretical value, given that the solute would not have as much impact on the pure substance, p-xylene. This would raise the Kf value, bringing it closer to the solvent’s Kf. Another source of error resulting in the higher Kf could have resulted from contamination of the solvent or solute, given that it could introduce a polar substance or different molecules which would alter the hydrogen bonding.
Refrigeration is the removal of heat from a space or body at a temperature lower than the surrounding temperature. It should be kept in mind that refrigeration...
This is expressed as Δ +ve (delta positive). If the total energy put in is less than the energy created, then the substance warms up (it is exothermic). This is expressed as Δ -ve (delta negative). I will investigate eight different alcohols using an alcohol or spirit burner, to measure the energy change during burning by measuring the change in temperature of some water held in a container.
Aerogel was discovered in the late 1930’s by chemist Samuel Stephens Kistler. He accomplished this by the process of supercritical fluid drying. A supercritical fluid is any substance at a temperature and pressure above its critical poi...
Also, when we put the insulation cans in warn water the water heated up the can. And lastly, in the insulated can experiments, both cooling and heating, when the cans temperature was changed it in turn changed the air temperature
The rate of evaporation can increase if the gas pressure decreases around the liquid. Heat energy is used to break the bonds that hold water molecules together, that is why water easily evaporates at the boiling point but evaporates much slower at the freezing point. Net evaporation happens when the rate of evaporation surpasses the amount of condensation. Saturation occurs when these two process rates are equivalent when the humidity of the air is at one-hundred percent. On average, a fraction of the atoms in a glass of water has enough heat energy to escape from the liquid. Evaporation from the ocean is the primary device for supporting the surface-to-atmosphere part of the water cycle. Evaporation is the pathway where water moves from the liquid state back into the water cycle as atmospheric vapor. Studies have shown that the major bodies of water are nearly ninety percent of the moisture in the atmosphere from the evaporation of the water, the ten percent left is contributed from plant transpiration. Evaporation can only occur when water is available. It also requires the humidity of the surrounding atmosphere to be less than the evaporating surface. At one-hundred percent relative humidity, there is no more evaporation. The wind chill effect is one of the
As the pressure drop increases in the column, it is observed that the degree of foaming becomes more violent and more spread out. When the pressure drop is relatively high, it means that the pressure exerted by the vapour is insufficient to hold up the liquid in the tray, causing the gas bubbles to appear on top of the sieve trays. To add on, the higher the pressure drop, the higher the velocity of the vapour passing up the column. As a result, more vapour will penetrate the liquid and more bubbles formation is observed. Due to more bubbles formation, the degree of foaming are more agitated, rapid and spread out.
Capillary action can only occur when the adhesive forces are stronger than the cohesive forces, which creates surface tension in liquid. The kinetic energy produced when the liquid is heated, allows the attractive forces between the molecules to weaken and this causes them to move past each other more freely. This results in the liquid flowing more easily. Therefore temperature increases capillary action and capillary flow because of the decrease in cohesive force. The intermolecular forces between the molecules are less packed due to the increase in temperature and the surface tension in the liquid will decrease as the temperature increases and this will help the flow of the liquid through the capillary tube.
As air humidity is in an instance of increasing, its ability to absorb water vapor decreases and evaporation rate slows down. For evaporation to undergo there must be a difference in humidity (Tenalem Ayenew and Tamiru Alemayehu, 2001; Fetter C.W, 1994).
6. When water is distilled, it does not vaporize all at once when the boiling point is reached. When some water molecules evaporate, the kinetic energy of the remaining liquid goes down and the temperature drops slightly. As a result, the rest of the water needs to be heated again before more molecules of water evaporate. A constant source of heat is needed.