Explain the results in terms of polarities and/or hydrogen bonding.
- water and ethyl alcohol= miscible
water is highly polar and ethyl alcohol has intermediate polarity.
- water and diethyl ether= immiscible
water is highly polar and diethyl ether is only slightly polar
- water and methylene chloride= immiscible
water is highly polar and methylene chloride is what?
- water and hexane= immiscible
water is highly polar and hexane is nonpolar
- hexane and methylene chloride= miscible
hexane is nonpolar and methylene chloride is ? nonpolar?
Are these correct? Also, if you can add any info. on the polarities or include hydrogen bonding in the explanation please do.
It is not that easy to do these predictions just based on polarity. You need to consider the molecule's ability to hydrogen bond (i.e. is it hydrophylic?) or contains a large hydrocarbon part which makes it hydrophobic.
If we start with the alcohols, the short chain alcohols (methanol and ethanol) are miscible with water as the OH can hydrogen bond with water molecules. In addition the small hydrocarbon part makes them very much less hydrophobic than a molecule with a longer hydrocarbon chain. As the chain length increases the molecule becomes more hyrdophobic and the solubility in water decreases.
A similar effect is seen with the ethers. Dimethyether is soluble in water whereas diethyl ether with more hydrocarbon is much less soluble 'immiscible' although there is an appreciable solubility in water.
The chlorinated compounds chloromethane through to carbontetrachloride are polar organic molecules, but because they cannot hydrogen bond with water are immiscible with water, i.e. are hydrophobic.
Does this help?
Somewhat, but still a little confused about the individual cases. Thanks though.
why is water and tetrachloride immiscible
Yes, your explanations are correct! Let's delve into more detail regarding the polarities and hydrogen bonding in these scenarios:
1. Water and Ethyl Alcohol: Both water and ethyl alcohol are polar molecules. Water is highly polar due to its bent molecular structure and the unequal sharing of electrons between oxygen and hydrogen atoms. Ethyl alcohol also has intermediate polarity as it contains an oxygen atom that creates a partial negative charge. The presence of hydrogen bonding between the polar molecules of water and ethyl alcohol allows them to mix and form a homogeneous solution.
2. Water and Diethyl Ether: Water is highly polar as mentioned earlier, while diethyl ether is only slightly polar. Diethyl ether has an oxygen atom like ethyl alcohol, but its molecular structure is linear, reducing the overall polarity. The weak or negligible polarity of diethyl ether results in the absence of significant hydrogen bonding with water. Hence, they are immiscible and don't mix well together.
3. Water and Methylene Chloride: Water is highly polar, but methylene chloride is a nonpolar molecule. Methylene chloride consists of two chlorine atoms attached to a carbon atom and does not contain any highly electronegative atoms to create polarity. Consequently, water and methylene chloride lack significant intermolecular forces such as hydrogen bonding, making them immiscible.
4. Water and Hexane: Water is highly polar, while hexane is a nonpolar molecule. Hexane consists of only carbon and hydrogen atoms, lacking any significant electronegative atoms to create polarity. Similar to the previous cases, the absence of hydrogen bonding and other polar interactions leads to immiscibility between water and hexane.
5. Hexane and Methylene Chloride: Hexane is nonpolar, and methylene chloride is also a nonpolar molecule. Both molecules lack any significant electronegative atoms to create polarity or establish hydrogen bonding. This similarity in nonpolarity allows hexane and methylene chloride to mix and form a homogeneous solution.
Understanding the polarity and hydrogen bonding characteristics of molecules helps explain their solubility or miscibility behavior when they come into contact with each other.