Question

Ma ajutati si pe mine cu urmatoarele probleme va rog?
1) Calculati masa solutiei de HCL de concentratie 18% ( ro=1,09g/mol) , necesar prepararii a 500 ml solutie HCL 1M ( MHCL=36.5)
2)Calculati cantitatea (moli) de NaOH , care reactioneaza cu 100ml solutie de H2SO4 de concentratie 2 moli/L (MNAOH=40 , MH2SO4=98)
3)Piatra vanata este un cristalohidrat care are formula moleculara CuSo4x5H2O. Calculati concentratia procentuala a solutiei obtinuta prin dizolvarea a 50g piatra vanata in 270g de apa .

Va rog frumos sa ma ajutati!!

Answer 1

Notez "*" Inmultire si "/" Impartire

1) Vs=500ml
Cm=1M
Cm=md/M*Vs==>md=Cm*M*Vs(L)=1*36.5*0.5=18.25g HCl
Cp=md/ms*100==>ms=md*100/Cp=101.38g HCl
2) Vs1=100ml
Cm=2M
Cm=md/M*Vs(L)==>md=Cm*M*Vs(L)=2*98*0.1=19.6g

2*40g........98g
2NaOH + H2SO4 ---> Na2SO4 + 2H2O
x=16g...............19.6g

n=m/M=16/40=0.4 moli NaOH

3) MCuSO4*5H2O=64+32+16*4+5*18=250g/mol
mH2O=90g
manhidru=160g

md=50g
mH2O=270g

ms=md+mH2O=50+270=320g
Cp=md/ms*100=50/320*100=15.625%