Răspuns:
Explicație:
Hristos a inviat!
Problema 3
Date
md=80g HNO₃
m H₂O=100g
Cerinta
c=?%
Rezolvare
ms = md + m H₂O⇒ ms =80+100=180
c/100=md/ms⇒c=md×100/ms⇒c=80×100/180=44,44%
Problema 4
Date
c=20%, solutie H₂SO₄
V=400 ml=0,4 L
cM=1
Cerinta
ms=?g
c/100=md/ms⇒ms=md×100/c
cM=n/V(L)⇒
n=cM×V(L)⇒
n=1×0,4=0,4 moli H₂SO₄
M H₂SO₄=2+32+64=98g/mol
1 mol.........................98g H₂SO₄
o,4moli.......................a
a=0,4×98=39,2 g H₂SO₄(md)
ms=39,2×100/20=196 g
