Which evaporates more quickly: 55 mL of water (H₂O) in a beaker or 100 mL of acetone [(CH₃)₂CO] in an identical beaker under identical conditions? Is the vapor pressure of the two substances different? Explain.

Video transcript

hey everyone in this example, we need to identify which of the below substances will evaporate faster in identical conditions and amounts. So what we want to recall is a concept of vapor pressure and we should recall that compounds with stronger inter molecular forces will have lower vapor pressure. And that therefore means that we have more energy that is required two separate the particles. So we should recognize that our first compound, which we recognize as benzene just consists of carbon and hydrogen. So we would recognize this as a hydrocarbon. We also want to recognize that because we have six carbons and six hydrogen in this molecule, we have a symmetrical molecule. And so therefore this is going to be a non polar molecule, meaning that the only inter molecular force present is therefore going to be our London dispersion inter molecular force. And because we recall that this is going to be a weaker inter molecular force. This will correspond to a higher value for vapor pressure for our compound benzene. So now we want to consider our next molecule, Which we would recognize as one Pen Tunnel. So we want to identify that within this molecule, we have specifically oxygen bonded to hydrogen, where oxygen is a non metal to the other nonmetal hydrogen. And because we have this specific bond here, this signals that we have the inter molecular force hydrogen bonding occurring or present. And so this is holding our particles in our one pentagonal together. And because we recall that hydrogen bonding is one of our stronger inter molecular forces which is much stronger than London dispersion forces. As we saw in benzene, we can say that this will correspond to a lower vapor pressure. So overall we can say that the vapor pressure of benzene, Sorry, that should be C6 is greater than the vapor pressure of our one pen tunnel C five H 12 0. H. And so therefore, benzene will evaporate faster. And so for our final answer, we have this explanation here that I've outlined. So if you have any questions, please leave them down below. Otherwise, I will see everyone in the next practice video.