Hi there! Thank you for the opportunity to help you with your question!
A vapor pressure is another measure of a substance's evaporation rate. The high vapor pressure means high evaporation rate, and low vapor pressure means low evaporation rate.
Now, we are comparing 1,3-dimethylcyclohexane, which is a hydrocarbon (made up of carbon and hydrogen only), and water, which has hydrogen and oxygen. The main difference between these two are the intermolecular forces; water has hydrogen bonds, and hydrogen bonds are very strong, whereas dimethycyclohexane only has Van der Waals' forces, which are relatively weak.
Therefore, what we are comparing is which one of these is easiest to evaporate. Because water has a stronger bonding, then it is much harder to get water to evaporate. Dimethylcyclohexane would evaporate much easier, so we can conclude that it would have a higher vapor pressure than water.
Hope this helps!
Please let me know if you need any clarification. Always glad to help!
Aug 23rd, 2015
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