meltboil - Introduction In this experiment two different...

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Introduction In this experiment two different physical properties, melting point and boiling point are examined. The melting points of an impure benzoic acid, 114 °C - 120 °C, and a recrystallized benzoic acid, 119 °C - 122 °C, were found and compared, and the boiling point of an unknown substance were found in order to determine the identity of that substance, which was ethanol. Theory, Reactions, and Mechanisms Physical properties are those properties of a material which depend on the chemical composition of the substance. The melting point of a solid can be defined as the temperature at which a substance changes from the solid state to the liquid state. A melting point is actually a range of temperature, the temperature at which the solid begins to melt until the temperature at which the sample is entirely melted. The determination of a substance’s melting point can serve two major purposes, the identification of unknowns and the determination of purity. Pure solids will have a melting point range with a 1°C or 2°C difference. Impure substances have melting points with ranges larger than 1°C or 2°C because impurities in a solid lower the melting point of the sample. This increases the size of the melting range. When it comes to identification of unknowns, melting points are useful since many substances have melting points that are exclusive to that substance. Boiling point is the temperature at which a liquid turns to a gas. Boiling points are also useful for determining purity and for identifying an unknown compound. Impurities in a liquid cause a higher than expected boiling point range. A boiling point may also be described as the temperature at which P A = P ATM , or when the pressure inside the container is equal to the atmospheric pressure. This is why it often takes more energy to boil a liquid at high altitudes,
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where there is less air pressure. Reagent Table
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meltboil - Introduction In this experiment two different...

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