[KdeK]

Hello,

For our school assignment I had to test the purity in percentages of my own made methylacetate ester. However this presented some issues. I thought of many things. There are very useful methods such as massspectrometry or IR-spectrometry, but unfortunately those are not executable on my school. I thought of colorimetry but I faced a problem, methylacetate is colorless. Is it possible to add a color to the methylacetate in order to determine the concentration?

I also thought of gas chromatography, but methylacetate is liquid at roomtemperature (293 Kelvin). Is it possible to heat the solution first so that it evaporates and then add this gas to our chromatography setup?

Info:
The ester was made by adding a sulphuric acid as the catalyst to a mixture of methanol and acetic acid. I also heated the mixture.

[Burner]

I also thought of gas chromatography, but methylacetate is liquid at roomtemperature (293 Kelvin). Is it possible to heat the solution first so that it evaporates and then add this gas to our chromatography setup?

Gas chromatography is possible, but you don't need it. The bold words in the quote is a hint. Try to think of something simpler .

[KdeK]

Oke I'll try my best. Can I distill? But what if there's still methanol in the mixture, isn't the proximity in boiling temperatures too large? Thanks for helping me, this forum is really helping me understand chemistry.

[Burner]

Oke I'll try my best. Can I distill? But what if there's still methanol in the mixture, isn't the proximity in boiling temperatures too large? Thanks for helping me, this forum is really helping me understand chemistry.

You have got the point here. If there are impurities in your mixture, the boiling point of it will increase(boiling point elevation). So, to test the purity of your own made methylacetate ester you can test its boiling point. If pure, the mixture should have a sharp boiling point(completely boils over a very narrow range of temperature) which matches the theoretical value of methylacetate ester (56.9°C, from Wikipedia).

[KdeK]

Thank you so much! So by checking whether the boiling temperature is the same as what it should be for methylacetate, I'm able to find out whether this ester is pure or not. Awesome.

[DrCMS]

I also thought of gas chromatography, but methylacetate is liquid at roomtemperature (293 Kelvin). Is it possible to heat the solution first so that it evaporates and then add this gas to our chromatography setup?

You do not need to have the sample in the gas phase before you inject it to the GC, liquids work just fine.