Methane (CH4) is an alkane compound and have a low boiling point. Here, we discuss why CH4 has a lower boiling point and reasons to it. Also, we compare boiling points of another several compounds with methane to highlight special cases of boiling point of methane.
Boiling point of methane is -161.50C. If it is expressed in Fahrenheit, it is -258.70F.
You see boiling of CH4 is a negative one and it is very low too. Why I say like that, methane has a low boiling point? Compare its boiling point with water! Both, water and methane molecules are very small. But, they have different characteristics such as boiling point.
Here we are going to discuss why methane's boiling point is low. There are several reasons why boiling point of methane is less.
When molecular mass of a molecule is small, boiling point value decreases too.
Methane's molecular mass is 16. It is the lowest molecular mass in alkane compounds series. Therefore, boiling point of methane has the lowest boiling point in alkane series.
Both methane and hexane are alkanes. But hexane has six carbon atoms while methane only has one carbon atom. When we consider
molecular mass of hexane and methane, hexane has a higher molecular mass. Due to higher molecular mass, hexane's boiling
point is higher than methane.
C-H bonds are very weakly polarized because electronegativity difference between carbon and hydrogen atoms are very small. So their dipole - dipole interactions are too weak. So, methane are considered as non-polar compound and consider there are only weak London dispersion forces which are the lowest strong intermolecular forces.
Boiling point of oxygen is -1830C. Oxygen is a non-polar compound and there is only London dispersion forces. So, intermolecular forces of methane molecules are greater than oxygen molecules.
Questions
Boiling points are incresed in following way.
Methane < methanal < methanol < methanoic acid
Boiling point is asked from Kelvin. Therefore, it cannot be a negative value. So, answer 1 is wrong. Also, we know, at room temperature methane exist as a gas. Usually, room temperature is around 300K. Therefore, boiling point of methane cannot be over 300 K. Then, answers 3 and 4 are wrong. Now, we know answer is 2.
methanol's boiling point is higher than methane because methanol can form strong hydrogen bonds. Also, molecular mass of methanol is higher than methane. That is another reason why methanol's boiling point is higher than methane.
Yes. you can. Boiling point of methane is well below than room temperature. This can be applied for so many compounds.
Whether molecules are non-Polar, their boiling points may be higher due to larger molecular weight such as hexane, iodine and more.
When you know the boiling point in Celsius, add 273.15 to value of celsius. For methane, -161.5 + 273.15 = 111.65 K.
Water molecules can form strong hydrogen bonds between water molecules. But methane cannot form. Therefore, due to strong intermolecular forces, water has a higher boiling point. Special thing is, whether both methane's and water molecular mass are similar and small, boiling point of water is very hiigher than methane.
