Question

datele problemei: 14,8 g Ca(OH)2 0,2 moli acid carboxilic , 25,64%Ca sare;Determinati: formula moleculare 2. cantitatea de sare.

Answer 1

Determinam daca e mono sau dicarboxilic
Ca fiind un metal divalent, sarea va fi formata din 2moli de ioni de carboxilat, daca e monocarboxilic si un mol, daca e dicarboxilic
notam acidul acidul intai: A
nmoli....74g
nA + Ca(OH)2 -> AnCa + (1 sau 2)H2O
0,2.......14,8g
n=74*0,2/14,8=14,8/14,8=1 => acidul e dicarboxilic
acidul are urmatoarea structura: HOOC-(CH2)n-COOH
sarea arata astfel: (CH2)n=(COO)2Ca
Msare...................100%
40g.......................25,64%
Msare=40*100/25,64=156g/mol
Msare=14n+88+40=156g/mol
14n=156-128=28 => n=2 => acidul butandioic sau succinic
1mol...................................................156g
HOOC-(CH2)2-COOH + Ca(OH)2 -> (CH2)2=(COO)2Ca + 2H2O
0,2moli...............................................x=?
x=0,2*156=31,2g sare