Question

Ajutor ! Dau Coroana ! Problema 8,9 si 10 !

Answer 1

8. a) daca ms = 100g   mH2SO4 = 9,8g    n1 = 9,8/98 = 0,1 moli
mH2O = 90,2 g    n2 = 90,2/18 = 5,01 moli 
n = n1+ n2 = 5,11moli    %H2SO4 = 0,1·100/5,11 = 1,957%
%H2O = 501/5,11 = 98,043%
b) ptr. ms = 100g    Vs = 100/1,1 = 90,9ml = 0,0909 l   n = 0,1 mol
cM = 0,1/0,0909 = 1,1 mol/l
9.  initial :  msi ;   ci = 10%  ⇒ md = 0,1msi     mH2O = msi - 0,1msi = 0,9msi
final : msf = msi - 0,45msi = 0,55msi    md = 0,1msi ⇒⇒⇒
⇒⇒⇒ c = 0,1msi·100/(0,55msi) = 18,18%
b) nNaOH = 0,1msi/40    nH2O = 0,45msi/18
nNaOH/nH2O = 0,1/40 ·18/0,45 = 1/10
10.  ms = 3,12 + 2,95 + 2,22 + 0,9·18 = 24,49g
%NaBr = 3,12·100/24,49 = 12,74%     %NaCl = 295/24,49 = 12,04%
%CaCl2 = 222/24,49 = 9,06%
b) nNa⁺ = nNaBr + nNaCl = 3,12/103 + 2,95/58,5 = 0,03 + 0,05 = 0,08 moli
mNa⁺ = 0,08ₓ23 = 1,84g      c = 1,84ₓ100/24,49 = 7,389%
nCl⁻ = nNaCl + 2ₓnCaCl2 = 2,95/58,5 + 2ₓ2,22/111 = 0,05 + 0,04 = 0,09 moli
m = 0,09ₓ35,5 = 3,195 g    c = 3,195ₓ100/24,49 = 13,046%