Melting point determination lab report

Chelsey Grasham

Lab Report Assistant

Purpose: The purpose of this experiment was to determine melting and boiling points of certain substances.

Procedure: For this experiment, I collected different substances, heated them, boiled them, and observed them while recording data.

Conclusion: From this experiment, I learned that different substances have different boiling points and that the boiling/melting point of a substance can tell you about its identity.

Exercise 1: Determination of a Melting Point

Data Table 1. Melting Point of Tetradecanol.

Melting Point of Tetradecanol (°C)

Trial 1

38

Trial 2

39

Trial 3

40

Average of the 3 Trials

39

Questions

A. Describe your results for the melting point of tetradecanol. Were your results consistent? What was the range of values? My results remained fairly consistent and my values only ranged from 38-40 degrees Celsius.

B. Describe what occurs to the particles of a substance when the substance melts. Explain why this occurs. As a substance melts, the bonds begin to lose their strength and in turn, the substance turns into a liquid.

C. When performing this experiment, when is the tetradecanol in a condensed phase? Explain your answer. In this experiment, tetradecanol is in a condensed phase when it is a solid/going into the liquid stage. This must be due to the fact that the molecules are really close together.

D. Based on your observations of tetradecanol when it reformed a solid after melting, does tetradecanol form a crystalline or amorphous solid? Explain the difference between these two terms as part of your answer. I do not think tetradecanol is a crystalline solid because those kinds of solids usually go back to their solid form, from liquid the liquid form, in a very long time. This is not what happened. I believe it is a amorphous solid because it went back to a solid almost immediately.

E. Give some examples of how it might be useful to know the melting or boiling points of a substance. Think in terms of both scientific and commercial/industrial settings. Melting and boiling points are very important to know. For example, in commercial industries, like when jewelry is made, it is beneficial to know the melting points of the metals so they will be able to melt, and form the metals not jewelry. In a scientific point of view, it is important to know for safety and hazardous reasons.

F. Describe any possible sources of error for this exercise. Sources in error could include reading the thermometer incorrectly, setting the experiment up incorrectly, or not allowing things to heat for the time allowed.

Exercise 2: Temperature and Phase Changes

Data Table 2. Temperature and Observations for Heating Curve.

Time (Min)

Temperature (°C)

Observations

0

0

Starting point

1

6

Starting to change form around 25 seconds

2

9

70 percent liquid

3

15

90 percent liquid

4

30

100 percent liquid

5

55

Bubbles beginning to form

6

72

7

90

bubbling

8

99

Starting to boil really quickly

9

100

Beginning to steam

10

100

Condensation and steam forming

11

100

Condensation and steam forming

12

100

Condensation and steam forming

13

100

Condensation and steam forming

14

100

Condensation and steam forming

15

100

Condensation and steam forming

16

100

Condensation and steam forming

17

100

Condensation and steam forming

18

100

Condensation and steam forming

19

100

Condensation and steam forming

20

101

Still boiling

21

102

Still boiling

22

101

Less water, a lot of steam

23

100

Less water a lot of steam

24

100

Less water a lot of steam

25

101

Condensation and steam

26

101

Condensation and steam

27

100

Condensation and steam

28

101

Liquid getting less and less, steam

29

101

Steam and condensation

30

100

Almost no liquid, steam