Question

I crushed acetamide and heated until melted, i let it cool and started again.

Melting Point of Acetamide (°C) Trial 1 80 C Trial 2 82 C Trial 3 81 C Average of the 3 Trials 81 C

A. Describe your results for the melting point of acetamide. Were your results consistent? What was the range of values?

B. The published melting point of acetamide is 81°C, calculate the percent error between your experimental values and the published (theoretical) value. Show your work.

C. Describe what occurs to the particles of a substance when the substance melts. Explain why this occurs.

D. When performing this experiment, when is the acetamide in a condensed phase? Explain your answer.

E. Based on your observations of acetamide when it reformed a solid after melting, does acetamide form a crystalline or amorphous solid? Explain the difference between these two terms as part of your answer.

F. 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.

G. Describe any possible sources of error for this exercise.

Answer 1

A. Describe your results for the melting point of acetamide. Were your results consistent? What was the range of values?

• This is a consistent result. The range is +1 and -1. The sample is a pure one.

B. The published melting point of acetamide is 81°C, calculate the percent error between your experimental values and the published (theoretical) value. Show your work.

• The Formula for Percent Error is a follows:

(EV – AV) /AVx100 = percent error   

Where,

EV= Estimated Value (measured value!)

AV= Actual Value

It is multiplied 100 to make the decimal a percent.

The answer is “No error”

C. Describe what occurs to the particles of a substance when the substance melts. Explain why this occurs.

• In solids the intermolecular forces, like lattice energy, London forces, are strong and tightly hold the molecules together. When it is heated the intermolecular force get weaker and distances between the molecules increases and then it comes to equilibrium of solid and liquid which is the melting point.

D. When performing this experiment, when is the acetamide in a condensed phase? Explain your answer.

• When it is heated the intermolecular force get weaker and distances between the molecules increases and then it comes to equilibrium of solid and liquid which is the condensed phase.

E. Based on your observations of acetamide when it reformed a solid after melting, does acetamide form a crystalline or amorphous solid? Explain the difference between these two terms as part of your answer.

• When it reformed, it would be amorphous, no definitive texture but crystalline is shiny and definitive texture.

F. 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 point and boiling points are the physical properties of matters and these can be useful for identification.

A fixed boiling point gives a fixed temperature for various chemical transformations.

Water gives 100 ^oC constant boiling at STP for cooking food.

G. Describe any possible sources of error for this exercise.

• Calibration of instrument and measuring the temperature