✔ 最佳答案
1.
dil. sulf. generally contains more ions than conc. sulf.
well, there're ions in conc. sulf., due to autoionization (or autoprotolysis or what):
2H2SO4 <======> H3SO4(+) + HSO4(-)
in fact conc. sulf. is a conductor of electricity.
however, i looked up the equilibrium constant of this reaction from Wikipedia,
K = 2.7E-4
and concentration of each ion is about 0.30M. with total ion concentration as 0.6M (considering 18M conc. sulf.).
well, the concentration of ions for conc. sulf. is quite significant, yet even 0.5M dil. sulf. has more ions than this.
2.
yes. they dissolve in water to give acidic solutions (carbonic acid; nitric acid and nitrous acid).
3.
same.
HNO3 + NaOH ------> NaNO3 + H2O
HNO3 + NH3 ------> NH4NO3
strength of bases do not vary the no. of mole of reagents needed for complete reactions.
as long as they're equimolar, complete reaction occurs (for acid-base reaction).
4.
as mentioned by Knowledge.
energy is needed (absorbed) for ionization of ammonia in rpoduction of ammonium ions. the overall heat realeased would be reduced.
5.
discard result of titration 1.
first calculate no. of mole of acid in the 25ml solution -- note the basicity of acid;
then calculate total no. of mole of acid used;
you have the mass and no of mole of acid, what else can't you get?
6.
yes.
pH = -log[H+]
pH = 0 when concentration of H(+) = 1M
theoretically, when concentration of proton is higher than 1M, pH can be negative.
it can be achieved by using higher concentration of REALLY strong acid, like hydrobromic acid, hydroiodic acid, perchloric acid, perioidc acid etc.
some "magic acid", composed of two or more chemicals, may also have this effect.
famous example is mixture of HF and SbF5, antimony pentafluoride:
HF + SbF5 ------> H(+) + SbF6(-)
the anion formed is a very veery weak base, making reverse reaction not possible. of course the medium of this reaction cannot be water.
2011-02-09 15:47:16 補充：
5.
yes, it's 195 g/mol.
remember the unit:
molar mass: g/mol
molecule mass: amu
