II
1.
ms = 80 g, c% = 6%
stim ca c% = mdx100/ms
=> md = msxc%/100 = 80x6/100 = 4,8 g clorura de potasiu
2.
Vs.HCl = a cm3, c% = 36,5%, ro.HCl = 1,11 g/cm3
V.apa = 2a , stim ca ro.apa = 1,0 g/cm3
din c% => md = msxc%/100
= roxVsxc%/100 = 1,11a36,5/100
=> md = 0,405a g
ms.final = m.apa + ms.initial
= 2a + 1,11a = 3,11a g
=> c%.final = mdx100/ms.final
= 0,405a100/3,11a = 13%
III.
1.
stim ca Cm = roxc%x10/miu, miuH3PO4 = 98 g/mol
=> Cm = 1,1x18x10/98 = 2 mol/L
2.
Vs.H2SO4 = 400 mL = 0,4 L, Cm = 0,1 M
=> niu = CmxVs = 0,4x0,1 = 0,04 moli H2SO4
n moli 0,04 moli
Ca(OH)2 + H2SO4 --> CaSO4 + 2H2O
1 1
=> n = 0,04 moli Ca(OH)2
din Cm => Vs = niu/Cm = 0,04/0,2 = 0,2 L sol. Ca(OH)2
