1.
1-b
2-a
3-f
4-e
5-c
2.
a)
ms1 = 200g , c1% = 20%
ms2 = 200g , c2% = 10%
stim ca c% = mdx100/ms
=>
md1 = ms1xc1%/100
= 200x20/100 = 40 g
md2 = ms2xc2%/100
= 200x10/100 = 20 g
=> md.tot = 40+10 = 50 g
ms.tot = ms1+ms2 = 400 g
=> c%.final = ms.totx100/ms.tot
= 50x100/400 = 12,5%
b)
md = 4 g NaOH, Vs = 250 mL = 0,25 L
stim Cm = md/miuxVs, miu.NaOH = 40 g/mol
=> Cm = 4/40x0,25 = 0,4 mol/L
3.
+5 -2 0 +2
HNO3 + H2S --> S + NO + H2O
2x N⁺⁵_+3e-_> N⁺² reducere (ag. ox) HNO3
3x S⁻²_-2e-_> S⁰ oxidare (ag red) H2S
2HNO3 + 3H2S --> 3S + 2NO + 4H2O
