Use the normal boiling points propane (C3H8) -42.1 °C butane (C4H10) -0.5 °C pentane (C5H12) 36.1 °C hexane (C6H14) 68.7 °C heptane (C7H16) 98.4 °C to estimate the normal boiling point of octane (C8H18). Explain the trend in the boiling points.

Video transcript

Hello everyone today, we are being asked to consider the following bullying points of several hydrocarbons. As we note that there are as we increase the number of carbons that we have. So if we go from 5 to 6, the boiling point increases. And this is also true with the number of hydrogen is that we increase. So the observed trend is that the longer the carbon chain or the C chain, it's going to, it's going to lead to an increase in the polarized, able, so polarized able electron cloud, meaning there's going to be more electrons available, which is going to also lead to an increase in London dispersion forces, abbreviated as L. D. F. And this in turn is going to have a profound effect on the boiling point and it's also going to increase the boiling point. And so we say that the greater number of carbons that we have, the stronger the London dispersion forces, hence the higher boiling point. And so if we're asked to find the boiling point of decade, which has 10 carbons and 22 hydrogen and we've seen that this trend leads to an increase in about 25 to 30 degrees Celsius. We can therefore say that the boiling point of c 10 H 22 is roughly 170°C 275°C. I hope this helped. And until next time