acids, bases, etc

[nemzy]

Suppose u let an acid sample sit for a week, does it lose weight after a period of time? and a base sample gain weight after a period of time? why is like this? and when a sample gains weight, the melthing point rises. is it because of the increased intermolecular forces? thanks

[garytse86]

very strange - never heard of this

[chem_tr]

Your logic is interesting. You should better consider equilibrium phenomenon; and Lavosier's very principle. An isolated system neither loses nor gains weight.

Your query reminds me of water absorption capacity of bases; as hydroxide ions are very powerful bases, hydrogen bonding may be excessive to absorb large quantities of water. Gaseous-originated mineral acids like HCl may lose weight as some of HCl evaporates away.

[pack_rat2]

Suppose u let an acid sample sit for a week, does it lose weight after a period of time? and a base sample gain weight after a period of time? why is like this? and when a sample gains weight, the melthing point rises. is it because of the increased intermolecular forces? thanks

I'd suspect the sample is either evaporating or absorbing moisture from the air.

[poolwin2001]

when a sample gains weight, the melthing point rises
ARE you saying When Molecular mass increases(similiar compounds)melting point rises?
{ethane,ethane,propane }

In case of absorption/evaporation of water,there is a change in Freezing point/Boiling point in non ideal solutions which is proportional to molality.

[garytse86]

what is molality

[Bystander]

Weight gain? Sure, picking up water --- and, carbon dioxide. The second item is the melting point booster.

[pack_rat2]

This is a lot of speculation about a "sample" we know very little about. Questions: What compound is it? Under what conditions have it been stored? Any further info would help. As for the question about molality, it's moles of solute per kg of solvent, of a solution.

[poolwin2001]

Molality:no of moles of solute /kg of solution.

[pack_rat2]

Molality:no of moles of solute /kg of solution.
Nope, it's moles solute/kg solvent. See: http://www.chemistry-dictionary.com/Molality