This week we did a lab about several liquids and their changes in temperature which were caused by evaporation. The liquids we used were methanol, ethanol, 1-propanol, 1-butanol, n-pentane, and n-hexane.
First of all we took two little pieces filter paper and and put it around the tops of two temperature probes. Then we put two rubbers around it so that it keeps holding it tightly.After this we connected the temperature probes with the computer. Then we put some methanol in one test tube and some ethanol in the other test tube. After this we put one temperature probe in each test tube. We waited about a minute and then we pulled the probes out and we put both probes on the table. We waited about 3to 5 minutes in order to see the highest temperature and the lowest temperature on the computer.
We did this procedure with for methanol, ethanol, 1-propanol, 1-butanol, n-pentane, and n-hexane.
Then we subtracted the lowest temperature from the highest. If you do this you figure out the difference between the highest and the lowest temperature. You can see it on the graph below.
First of all we took two little pieces filter paper and and put it around the tops of two temperature probes. Then we put two rubbers around it so that it keeps holding it tightly.After this we connected the temperature probes with the computer. Then we put some methanol in one test tube and some ethanol in the other test tube. After this we put one temperature probe in each test tube. We waited about a minute and then we pulled the probes out and we put both probes on the table. We waited about 3to 5 minutes in order to see the highest temperature and the lowest temperature on the computer.
We did this procedure with for methanol, ethanol, 1-propanol, 1-butanol, n-pentane, and n-hexane.
Then we subtracted the lowest temperature from the highest. If you do this you figure out the difference between the highest and the lowest temperature. You can see it on the graph below.
On the graph above you can see that both n-pentane and n-hexane have the highest difference between the highest temperature and the lowest temperature.
This happens because of the hydrogen bonds. Since n-pentane and n-hexane are not alcohols they don't have an O-H group so the H cannot form a bound to the other n-pentane/n-hexane.
In contrast alcohols do have an O-H group. The hydrogen atoms are charged delta positive because it gives his one electron to the O and then it's out of electrons. And if an atom gives away an electron it is charged positive because electrons are charged negative so the atom loses its negative charge. But because the O gets an electron from the H it's charged delta negative because it gets an electron which is charged negative. So the Delta positive charged H(of one alcohol) and the delta negative charged O(of another atom) attract each other enough so that they kind of form a bonding even without electrons on each sides.Then there is a surface tension. This leads to that the alcohols are harder to pull apart because they are connected even though they are no connected with electrons. So now the atoms they are more sticky because of the O-H bond. The O-H bond avoids that little molecules can come out of the alcohol so its temperature difference is not as high as the temperature difference of the not alcohols.
As you can see on the chart above 1-butanol has the lowest difference in its temperature. This happens because it has very many O-H bonds so there are even less molecules released during the reaction. If we kept going and we used for instance pentanol (the alcohol) the temperature difference would be even less because it has more O-H bonds than 1-butanol.
As you can see on the chart above 1-butanol has the lowest difference in its temperature. This happens because it has very many O-H bonds so there are even less molecules released during the reaction. If we kept going and we used for instance pentanol (the alcohol) the temperature difference would be even less because it has more O-H bonds than 1-butanol.
Since n-pentane and n-hexane are not alcohols they don't have the O-H bond and they do not have a surface tension which makes them lose more molecules than the alcohols do and they are not very sticky, either.
