Melting point Lab report PDF

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Lab report for melting point lab...

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Melting point

Abstract: In the melting point lab, we were looking at the different melting points for different substances. Then, we created three mixtures where we mixed the two substances (Urea and Cinnamic acid) in different ratios and tested for their melting point variations. Fortunately, we were able to collect data that is very close to the known properties of Urea and Cinnamic acid. We got 135 C for Urea and 133 C to Cinnamic acid. We also noticed that the variations in ratios significantly affect their melting point. For example, the 1:1 ratio has a melting point of 107 C, 1:4 has a melting point of 110 C, and 4:1 has a melting point of 122 C. Objectives: 1. We will use the melting point range of a substance to help us determine its general purity. 2. We will examine the melting point of an unknown substance to help identify it. Chemical Index:

Urea

Cinnamic acid

Physical properties: property Chemical formula Melting point Boiling point

urea CH4N2O or NH2CONH2 132.7°C (271°F) It decomposes before

Cinnamic acid C9H8O2 133°C 572°F (300°C)

density

boiling 1.33 g/cm3

1.25 g/cm³

Procedure: Attached at the end of lab report Data and calculations: Substance Urea Cinnamic acid Unknown 4:1 mixture 1:1 mixture 1:4 mixture

1st Melting point 135 – 137 C 133 – 136 C 123.6 – 125.7 C 122 – 130 C 107.6 – 113.4 C 110 – 118 C

Revised melting point 132 – 133.4 C 122.8 – 124 C 120 – 123.9 C -

To Calculate the percent error for Urea and Cinnamic acid melting point, I took the average of their melting range: Observed urea melting point average: 135+137/ 2 = 136 C Percent error for Urea melting point: (136 – 133 / 133) x 100 = 2.25 % Observed Cinnamic acid melting point average: 122.8 + 124/ 2 = 123.4 C

Percent error for Cinnamic acid melting point: (133 – 123.4 / 133) x 100 = 7.2 % Results and discussion: In the melting point experiment, we tested for the melting point of main three substances (Urea, Cinnamic acid, and Unknown.) Then, we mixed the urea and cinnamic acid if three different ratios (1:1, 1:4, and 4:1.) The melting points we got for Urea, Cinnamic acid, and Unknown are as following: 135 C, 133 C, 123 C. The melting points we got for the 1:1, 1:4, and 4:1 are as following: 107 C, 110 C, 122 C. We had to redo three tests to get a better result, and that is due to multiple errors such as reading the temperature at a wrong time, like too early or too late. Another possible error is the air spaces inside the capillaries and within the powder. A third error source is not crushing the powder evenly, which leads some areas to melt slower that others. As I performed this experiment, I learned how to use the heater that is designed for capillaries, and how to adjust the heat. I also learned how to insert the powder inside the capillary. Knowing what the melting point for every substance is very important in many ways. For example, airplanes use certain heaters and coolers to keep the hydraulic liquid at a specific temperature to function correctly. Also, in food science, dietitians and nutritionist use the melting point chart for certain food before taking a decision on whether this food shall be kept. Pharmacists also check the melting points for medications, so they know how to keep it and how to consume it....