Question

Mă ajută cineva la aceste probleme?
Vă rog.

Answer 1

SB II.

1. Cp=md/ms*100==>md=Cp*ms/100=6*80/100=4,8g KCl (clorura de potasiu) necesar prepararii solutiei..

2. Cp1=36,5%
ro1=1,11g/cm3
roH2O=1g/cm3
VH2O=?

Consideram ca solutia de HCl are 1L..

ro1=ms1/V==>ms1=ro1*V=1,11g/cm3*1000cm3=1110g HCl

Cp=md/ms*100==>md=Cp*ms/100=36,5*1110/100=405,15g HCl

ms=md+mH2O==>mH2O=ms-md=1110-405,15=704,85g 

roH2O=m/V=>V=m/ro=704,85g/1g/cm3=704,85cm3 H2O

Daca dublam volumul de H2O => 704,85*2=1409,7cm3 = g H2O

Cp=md/ms+mH2O*100=405,15/1110+1409,7*100=40515/2519,7=16%

nu sunt sigur..

SB III

1. Consideram V=1L

ro=ms/V=>ms=ro*V=1,1*1000=1100g H3PO4

Cp=md/ms*100==>md=Cp*ms/100=18*1100/100=198g H3PO4

MH3PO4=98g/mol

n=m/M=198/98=2,02 moli H3PO4

Cm=n/Vs=2,02/1=2,02 moli/L H3PO4

2. apa de var - Ca(OH)2

Cm=n/Vs==>n=Cm*Vs=0,1*0,4=0,04 moli H2SO4

1mol............1mol
Ca(OH)2 + H2SO4 ---> CaSO4 + 2H2O
0,04mol......0,04mol

Cm=n/Vs==>Vs=n/Cm=0,04/0,2=0,2L=200mL Ca(OH)2