Question

1) Calculati concentratia procentuala de masa pentru o saramura care contine 1,5 moli dizolvata in 250g H2O.

2) Calculati nr. de moli de apa care se gaseste in 2,5 Kg solutie de zahar cu C=25%

3) Cati moli de acid azotic se gasesc in 3,25 Kg solutie de acid azotic cu C=21,5%

4) Se prepara o solutie din 20g sare, 2L apa, densitatea apei - 1g/ml si 0,5 moli NaCl. Se cere concentratia procentuala

Answer 1

Răspuns:

Explicație:

M,NaCL= 58,5g/mol

m,NaCl= niuxM= 1,5X58,5g=87,75g=md

c=mdx100/ms,  unde ms=(md+m,apa)=337,75g

c= 87,75x100/337,75=.....................calculeaza !!!!

ms=2500g

md=cxms/100= 25x2500/100g=625g zahar

m,apa= ms-md= 2500-625=>1875g apa    cu  M,=18g/mol

niu=m/M= 1875g/18g/mol=......................calculeaza !!!!!

ms=3250g

md=cxms/100=21,5x3250/100g=698,75gHNO3   cu M= 63g/mol

niu=m/M=698,75/63mol=...........................calculeaza !!!

md1=20g sare

m,apa= roxv=1g/mlx2000ml=2000g

md2= niuxM= 0,5molx58,5g/mol=29,25gNaCL

md,total=49,25g

ms=md+m,apa= 49,25+2000=> 2049,25g

c= 49,25x100/2049,25=.......................calculeaza !!!!!