Pure Substance Lab Report

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Laboratory Experiment 2 B: Heating and Cooling Curves for a Pure Substance Observations and Data: | Cooling Process | Heating Process | Time (min) | Temperature (C°) | Observations | Temperature (C°) | Observations | 0 | 59 | Liquid Paradichlorobenzene was transparent | 20 | Whitish solid | 0.5 | 55 | | 28 | | 1 | 52 | | 29 | | 1.5 | 51 | The outside of the liquid began to solidify | 46 | | 2 | 51 | | 49 | | 2.5 | 51 | | 50 | | 3 | 51 | | 51 | Small amount of liquid formed | 3.5 | 51 | | 51 | | 4 | 51 | | 51 | | 4.5 | 51 | | 51 | | 5 | 51 | | 51 | | 5.5 | 51 | | 51 | | 6 | 51 | | 51 | | 6.5 | 51 | | 51 | | 7 | 51 | | 51 | | 7.5 | 51 | | 51 | | 8 | 51 | | 51 | | 8.5 | 51 | The outside of the liquid was solid; only a small portion inside remained liquid. | 51 | More…show more content…
| 56 | | 13 | 48 | | 57 | | Questions: 2. The freezing point of paradichlorobenzine is approximately 53.2 °C but my graph illustrates it as 51°C. (Note this is due to the different atmospheric pressures and concentration of paradichlorobenzine which causes some minor variation.) 3. The melting point of paradichlorobenzine is approximately 53.5 °C but my graph illustrates it at 51°C.( (Note this is due to the different atmospheric pressures and concentration of paradichlorobenzine which causes some minor variation.) 5. I can conclude that both the melting and boiling points of a pure substance are the (almost) the same. This is due to the fact that pure substances (unlike mixtures) have definite composition. And their components are always the same and are always combined in the same ratio by mass. Because of this, they will always have a constant melting point and boiling point. Follow-Up

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