Question

DAU 40 DE PUNCTE SI COROANA !!!!!
Pt. substanta denumita Ca(OH)₂ claculati :
a)Raportul de masa
b)compozitia procentuala de masa
c)masa de Ca continuta in 200g de Ca(OH)₂

Answer 1

a) 
masa Ca(OH)2 = 40+ 2*(16+1) = 74 g
m Ca: m O: m H = 40: 2*16: 2*1 = 40: 16: 2
=> m Ca: m O: m H = 20: 8: 1
b) %Ca = m Ca/m hidroxid * 100 = 40/74 * 100 = 54.054%
%O = m O/m hidroxid * 100 = 2*16/74 * 100 = 43.243%
%H = m H/m hidroxid * 100 = 2*1/64 * 100 = 2.7027%
c) 74 g Ca(OH)2...........40 g Ca
200 g Ca(OH)2............x g Ca
x = 108.108 g Ca

Answer 2

MCa(OH)2 = ACa+2(AO+AH) = 40+2(16+1) = 74g/mol

m Ca = 40g

mO = 16*2=32g

mH=2*1=2g

a) raport de masa => 40:16:2=20:8:1

b) %Ca=mCa/MCa(OH)2*100 = 40/74*100= Calculeaza!

%O=mO/M*100=32/74*100=

%H=mH/M*100=2/74*100=

c) In 74g Ca(OH)2 se gasesc...............40g Ca
In 200g Ca(OH)2..................................x

x=200*40/74
x=Calculeaza!