Melting Point Of Wax Experiment Pdf Free
Paraffin wax is mostly found as a white, odorless, tasteless, waxy solid, with a typical melting point between about 46 and 68 C (115 and 154 F),[8] and a density of around 900 kg/m3.[9] It is insoluble in water, but soluble in ether, benzene, and certain esters. Paraffin is unaffected by most common chemical reagents but burns readily.[10] Its heat of combustion is 42 MJ/kg.[11]
Melting Point Of Wax Experiment Pdf Free
Paraffin wax was first created in 1830 by German chemist Karl von Reichenbach when he attempted to develop a method to efficiently separate and refine waxy substances naturally occurring in petroleum. Paraffin represented a major advance in the candlemaking industry, because it burned cleanly and was cheaper to manufacture than other candle fuels. Paraffin wax initially suffered from a low melting point. This was remedied by adding stearic acid. The production of paraffin wax enjoyed a boom in the early 20th century due to the growth of the oil and meatpacking industries, which created paraffin and stearic acid as byproducts.[6]
Acceptable lipstick for the consumers should have a suitable texture and spreadability. Descriptive sensory profiling is an essential tool in this process as it allows an experienced panel to assess the qualitative and quantitative characteristics of a product [2]. Hardness and melting point are the main physical properties important for the stability of lipstick in all usage period and transportation. These characteristics can vary according to the composition of ingredients [3]. Therefore, the optimization of mixture composition is important and experimental design is very useful. Statistical mixture design is more satisfactory and effective than other methods such as classical one-at-a-time or mathematical methods because it can study many variables simultaneously with a low number of observations, saving time and costs [4]. In previous works, for the optimization of mixtures, D-optimal cross and mixed designs were used and were quite effective [4]. In this work, response surface central composite design was applied in order to investigate the relationship between composition, physical properties, and sensory analysis of consumers, which can be the most important factor [5].
Mixture of grapeseed oil and sea buckthorn oil was optimized by central composite design to obtain the highest free radical scavenging effect. The experimental mixture design of the amount of oils and the responses with DPPH inhibition percentages are shown in Table 1.
The thermal behavior of wax beads encapsulating ethyl vanillin was investigated by thermogravimetric (TG) and differential scanning calorimetry measurements (DSC) under heating conditions which mimicked usual food processing to provide information about the thermal decomposition of the wax matrix and the kinetics of aroma release. The TG-DSC measurements provide data regarding the melting point, thermal stability, weight loss during heating, as well as data, which can serve for further study of decomposition kinetics. The results could be useful for the formulation studies of food additives as well as for subsequent development of a stable and effective dosage form.
The slight variations in the enthalpy values and position of the melting point between samples may be explained by polymorphic transitions in the melt-cooled waxes, which are well documented in the literature [19]. However, DSC studies cannot be used to conclusively determine the physical state of ethyl vanillin in wax matrices.
Regarding isomers, the more branched the chain, the lower the boiling point tends to be. London dispersion forces are smaller for shorter molecules and only operate over very short distances between one molecule and its neighbors. It is more difficult for short, bulky molecules (with substantial amounts of branching) to lie close together (compact) compared with long, thin molecules. Cycloalkanes are similar to alkanes in their general physical properties, but they have higher boiling points, melting points, and densities than alkanes. This is due to stronger London forces because the ring shape allows for a larger area of contact.
Matter occurs in different states: solid, liquid, gaseous and plasma. When external conditions (such as temperature or pressure) change, the state of matter might change as well. For example, a liquid such as water starts becoming a gas when it is heated to its boiling point or starts to freeze when it is cooled to its freezing point. A state of matter with very high energy is plasma. Here, some of the orbital electrons are not bound to atoms or molecules anymore. Hence, plasma is a gas of free electrons and ions.
When the internal energy of a substance increases, e.g. by applying heat or pressure, a solid will eventually become a liquid. For example, ice cubes or a wax candle start melting when applying heat, whereby the pressure remains constant. However, solids such as ice or wax differ in their melting points. Whereas ice melts at a temperature of about 0C, wax melts at about 40C. When a substance reaches its melting point, the temperature of the substance does not increase further even if constant heat is applied, as long as there is some solid left to melt. Thus, the applied heat for melting a solid is also referred to as latent heat. Only when all the solid turned into a liquid state does the temperature begin to rise again.
The minimum temperature of a regular ice-water-mixture is the melting point of ice at 0C. You could use such a mixture as a cooling bath, e.g., for cooling a bottle of lemonade. However, there is one trick to make your cooling bath even cooler, i.e. to cool your lemonade more efficiently. The melting point of a substance such as ice can be depressed by adding a salt such as sodium chloride. Hence, an ice-water-salt-mixture ends up at a lower temperature than an ice-water-mixture.
Different hydrocarbons have different melting points, or the point at which they change from a solid to a liquid. If the wax has a high melting point, it takes more heat for it to change to a liquid. Plain paraffin candles have a relatively low melting point of 48 to 66 degrees Celsius. Paraffin candles can be made to last longer by adding other hydrocarbons that have a higher melting temperature, like stearin, which has a melting temperature of 70 degrees Celsius.
Beeswax is a natural type of wax, with a high melting temperature, between 60 and 66 degrees Celsius. In your experiment, depending on the type of beeswax and the amount of stearin added, you probably saw the paraffin burn the fastest, followed by the beeswax and then the paraffin with stearin.
Contrary to what one might expect, and contrary to what we did to make our pretend rock, most partial melting of real rock does not involve heating the rock up. The two main mechanisms through which rocks melt are decompression melting and flux melting. Decompression melting takes place within Earth when a body of rock is held at approximately the same temperature but the pressure is reduced. This happens because the rock is being moved toward the surface, either at a mantle plume (a.k.a., hot spot), or in the upwelling part of a mantle convection cell.[1] The mechanism of decompression melting is shown in Figure 3.8a. If a rock that is hot enough to be close to its melting point is moved toward the surface, the pressure is reduced, and the rock can pass to the liquid side of its melting curve. At this point, partial melting starts to take place. The process of flux melting is shown in Figure 3.8b. If a rock is close to its melting point and some water (a flux that promotes melting) is added to the rock, the melting temperature is reduced (solid line versus dotted line), and partial melting starts.
The determination of a melting point of a sample is a standard laboratory procedure and is relatively straightforward. It is used to identify a sample, establish its purity, and determine the thermal stability of the sample. When measuring a melting point, you will generally find that it is recorded as a melting range rather than the exact melting point. This is due to most samples appear to melt over a small temperature range. A melting range is a difference between the temperature at which the sample begins to melt and the temperature at which the sample has actually melted.
There are a variety of methods that you can use to determine the melting point of a sample. The most common and most basic method of determination is the capillary method. This method involves placing the sample in a capillary tube and running an experiment that will heat the sample until it reaches melting point. The melting point can then be recorded.
A more modern way of using the capillary method is to use a device called a Melting Point Apparatus. This device uses the same concept of heating a sample in a capillary tube but makes the process far simpler and quicker. There are many different types of Melting Point Apparatus machines and they range in functionality and accuracy. At a basic level, the machine is designed so that a capillary tube with the sample can be inserted into the device and rapidly heated to a set temperature. Generally, you will heat the capillary tube to near melting point and then decrease the speed of the temperature increase so that you can observe when the sample melts. Observation is generally conducted through a viewing eyepiece. A Melting Point Apparatus will more than likely have the temperature displayed in digital format for easy recording of data.
Finally, the tissue is infiltrated with the embedding agent, almost always paraffin. Paraffins can be purchased that differ in melting point, for various hardnesses, depending upon the way the histotechnologist likes them and upon the climate (warm vs. cold). A product called paraplast contains added plasticizers that make the paraffin blocks easier for some technicians to cut. A vacuum can be applied inside the tissue processor to assist penetration of the embedding agent.