3.Determinati raportul numarului de atomi si raportul de masa pentru: a) H20; b) HCI 4.Cate grame reprezinta: a) 2 moli acid sulfuric; b) 0,5 moli sulfat de calciu. 5.Cati moli reprezinta: a) 50g MgO; b) 149g KCI. 6. Calculati compozitia procentuala din mase molare sau moleculare pentru urmatoarele substante: a) acid carbonic (H2CO3); b) amoniac (NH3). 7. In ce masa de hidroxid de calciu, se gasesc 60g Ca? 8. In cate grame de apa si acid fosforic se gasesc 6g de hidrogen?
Răspunsuri la întrebare
Răspuns:
3.
a) H2O
r.at. H:O=2:1
r.m H:O=2:16=1:8
b) HCl
r.at.H:Cl=1:1
r.m H:Cl=1:35,5
4.
MH2SO4=2x1+32+4x16=98g/mol
m=nxM=2x98=196gH2SO4
b) MCaSO4=40+32+4x16=136g/mol
m=nxM=0,5x136=68gCaSO4
5.
MMgO=24+16=40g/mol
n=m/M=50/40=1,25moli MgO
b) MKCl=39+35,5=74,5g/mol
n=m/M=149/74,5=2moli KCl
6.
MH2CO3=2x1+12+3x16=62g/mol
62gH2CO3...................2gH.............12gC..............48gO
100gH2CO3....................x%H..............y%C.............z%O
x=100x2/62=calculeaza
y=100x12/62=calculeaza
z=100x48/62=calculeaza
b) MNH3=14+3X1=17g/mol
17gNH3............14gN...............3gH
100MH3.............t%N....................v%H
t=100x14/17=claculeaza
v=100x3/17=claculeaza
7.
MCa(OH)2=40+2x16+2x1=74g/mol
74gCa(OH)2.................40gCa
xgCa(OH)2....................60gCa
x=60x74/40=calculeaza
8.
MH2O=2x1+16=18g/mol
18gH2O....................2gH
xgH2O.....................6gH
x=6x18/2=calculeaza
MH3PO4=3x1+31+4x16=98g/mol
98gH3PO4.....................3gH
yg H3PO4........................6gH
y=6x98/3=claculeaza
Explicație: