Question

1.prin descompunerea termica a carbonatului de calciu rezulta 10 g oxid de calciu de puritate 90%. Calculati masa de carbonat de calciu si volumul de gaz degajat. 2.Calculati masa solutiei de acid sulfruic de concentratie 92 % ce reactioneaza cu 10g hidroxid de potasiu de puritate 78%.

Answer 1

M,Cao=56g/mol,    MCaCO3= 100g/mol        Vm= 22,4l/mol

deduc masa de CaO pur

p=m,px100/mi---> mp= 90x10/100g= 9g CaOpur

deduc cerintele problemei din ecuatia chimica

1mol.................1mol.....1mol       sau in grame si litri,

CaCO3----->   CaO +CO2

100g...............56g.........22,4 l

x.........................9...................y

x= 900/56 gCaCO3=.......................CALCULEAZA

Y= 9x22,4/56 l CO2=......................CALCULEAZA

CALCULEZ masa de KOH pur

78/100= md/10---> md=7,8 g KOH PUR

CALCULEZ masa de acid ce reactioneaza , din ecuatia:

2mol...........1mol...........................................sau, in grame

2KOH +  H2SO4----> K2SO4 + 2H2O

2x56g..........98g

7,8g.................m,H2SO4=6,825g H2So4......aceasta este masa dizolvata in solutie, md

calculez masa de solutie

c=mdx100/ms---> ms=100x6,825./92g=......calculeaza !!!!