[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

[Mitch]

Something might be desolving in your samples. Did you seal your samples or leave them open to air?

[ssssss]

Something might be desolving in your samples. Did you seal your samples or leave them open to air?

I agree.Some adition reaction is taking place that is increasing the weight of the solution.

[limpet chicken]

I imagine it would depend on the acid and the base, some acids, especially the halogen acids are volatile and will evaporate, whilst sulfuric, selenic and telluric acid are very high boiling and greatly less volatile.

Some bases, the alkali hydroxides in particular are very hygroscopic and will absorb atmospheric water, coult this perhaps be the cause?

[nemzy]

i left my samples open in my lab drawer

[dexangeles]

as specified already, you have to tell us what kind of acid or base you have
that makes a big difference, but seems like mad scientist got your answer already