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Posted by
Mark Neidorff

Solubility of methanol and ethanol in water

Corey Deane  Follow

How does a alcohol get soluble in water? The $\ce{H2O}$ molecule acts as bipolar and the positive pole forms some weak hydrogen attraction (name this 'bond' if you like) with the oxygen of alcohol. Now it's obvious, the more bulkier the group around oxygen, the less space around oxygen to form this bond. Hence $\ce{CH3OH}$ is more soluble in water than $\ce{C2H5OH}$. After all, $\ce{-C2H5}$ group is more soluble than $\ce{-CH3}$ group.

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Garni Khodaverdian  Follow
Yes ,you are quite right. But I just wanted to say that if there is even a slight difference in their solubility( say at the 10th decimal place {solubility in mol/litre}), then its probable reason is the one I gave.More
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Hussain  Follow
Except that, as many others have stated, both methanol and ethanol are infinitely miscible in water at room temperature.More
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Brian Tucker  Follow

Options 1 and 4 both have polar $\ce{C-O}$ bonds which make them soluble in water. The question is, which one is more soluble? To answer that, notice that the non polar part of methanol is smaller, so it will be more soluble.

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Charles Seymour  Follow

For primary alcohols, the trend is the longer the chain, the less soluble.

However, at room temperature, methanol, ethanol and propanol are all completely miscible with water.

At lower temperature, below the freezing point of water, there is finite solubility.

See the phase diagram that is Fig. 1 in CRYSTAL GROWTH OF WATER ETHANOL MIXTURE and that in Fig. 1 of Solid-Liquid Phase Diagram of the System Methanol-Water

Which alcohol would you choose for windshield deicing solution?

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