User: Which Material does not dissolve in water?

Weegy: Sugar (C12H22O11) and table salt (NaCl) are both highly soluble in water, while sand, candle wax, and nails are insoluble (for all practical purposes). Sugar and salt are soluble because they are both composed largely of polar and/or ionic bonds. [ Salt is an ionic diatomic ionic compound; it is composed of 2 atoms, a metal and a non-metal, with very different electronegativities, and hence it is polar. Because water molecules are also very polar, they can pull the salt molecules apart, hence dissolving them into their composite ions. Sugar is similar, but slightly different; basically, the hydroxyl groups and oxygen atoms make it polar enough to dissolve in polar solvents (ie, water) and form hydrogen bonds. Sand doesn't dissolve because it's made of covalently bonded atoms (silicates mostly). Going by the general "like dissolves like" solubility rule, and given then sand is covalent (non-polar), and water is polar, you know it won't dissolve. Candles don't dissolve for pretty well the same reason. Candles are usually made of paraffin wax, which is a long hydrocarbon chain. Hydrocarbon chains are also non-polar (covalent), and hence do not dissolve in water (unless they have enough hydroxyl groups to make them polar enough, such as with ethanol). Iron nails are a little more complicated, but suffice it to say that iron uses metal-bonding, which is non-polar, and similar to covalent bonding. Again, like dissolve like, so water (polar) does not dissolve iron (non-polar). It's not quite so simple, and iron does erode slowly, but think of the hull of a ship, or an old car: it rusts and erodes away, but only very slowly. http://answers.yahoo.com/question/?qid=20071125001329AAPQmac ]
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