N(H2S) = 0.125*10^23
n(H2S)=?
V(H2S)=?
m(H2S)=?
n(H2S)= N(H2S) / Na
n(H2S)= 0.125*10^23 / 6*10^23 моль^-1
n(H2S)=0.02 моль
* Na = 6*10^23 моль^-1 конста́нта Авогадро
n(H2S)= V(H2S) / Vm
V(H2S) = n(H2S)*Vm
V(H2S)= 0.02 моль * 22.4 дм^3/ моль
V(H2S)=0.45 дм^3
* Vm=22.4 дм^3/ моль моля́рный объём'
n(H2S)= m(H2S)/M (H2S)
m(H2S)= n(H2S)* M (H2S)
m(H2S)= n(H2S)* (2*Ar(H) +Ar (S) ) г/ моль
m(H2S)= 0.02 моль * (2*1 +32) г/ моль
m(H2S)= 0.02 моль *34 г/ моль
m(H2S)=0.68 г
*M(H2S) молярная масса сероводорода
3Fe(2+) + 6Na(+) + 2PO4(3-) + 3 SO4(2-) = Fe3(PO4)2 + 6Na(+) + 3SO4(2-)
3Fe(2+) + 2PO4(3-) = Fe3(PO4)2
Rb2SO3 + H2O = RbOH + RbHSO3
2Rb(+) + SO3(2-) + H2O <=> 2Rb(+) + HSO3(-) + OH(-)
SO3(2-) + H2O <=> HSO3(-) + OH(-)
Rb2SO3 = 2Rb(+) + SO3(2-) (electrolites and dissociation)
Hydrolysis of weak acid and strong base
OH(-) is formed in process ==> pH > 7 (basic solution)
"соль которая образуется в конце полного гидролиза."
Full hydrolysis (2 steps) Rb2SO3 + 2H2O = 2RbOH + "H2SO3"
How you can see, salts doesn't formed in full hydrolysis.
Ca3(PO4)2 + 2H2O = 2Ca(HPO4) + Ca(OH)2
Ca3(PO4)2 + 2H2O = 3Ca(2+) + 2HPO4(2-) + 2OH(-)
OH(-) is formed in process ==> pH > 7 (basic solution)
Ca(2+) and PO4(3-) - electrolites
диссоциацию солей на ионы.
Ca3(PO4)2 - weak electrolite
Ca3(PO4)2 <==> 3Ca(2+) + 2PO4(3-), Ks = 1*10^-25 , T=298K
Hydrolysis of weak acid and strong base
Full hydrolysis (3 steps) Ca3(PO4)2 + 6H2O = 3Ca(OH)2 + 2H3PO4
2CaCO3 + 2H2O = Ca(HCO3)2 + Ca(OH)2
2CaCO3 + 2H2O = 2Ca(2+) + 2OH(-) + 2HCO3(-)
OH(-) is formed in process ==> pH > 7 (basic solution)
Ca(2+) and CO3(2-) - electrolites
CaCO3 - weak electrolite
CaCO3 <==> Ca(2+) + CO3(2-) , Ks = 4,9*10^-9 , T=298K
Hydrolysis of weak acid and strong base
Full hydrolysis (2 steps) CaCO3 +2H2O = Ca(OH)2 + "H2CO3"
2K+S=K2S
Mr(K)=39 г/моль
Mr(K2S)=110 г/моль
3 г (K) --- x г
Mr(K)=39 Mr(K2S)=110
m(K2S)=(110*3)/39=8,46(г)
n=m/Mr=8,46/110=0,08 моль
ответ: 8,46 г; 0,08 моль