Question

determinati compozitia proncentuala.a) ca3 (po4)2 ; b) al(oh)3

Answer 1

Ca3 (Po4)2
M ca3(po4)2 =2xA ca +2xA p + 8xA O
                   =2x40 + 2x31+8x16
                   =80+62+128
                   =270
270 g _ _ _ _ _ _ _ _ 80 g Ca
100g  _ _ _ _ _ _ _ _  x

270/100 ( / = supra ) = 80/x => x=80x100/270 = 8000/270=29,63% Ca

270 g _ _ _ _ _ _ _ 62 g P
100 g _ _ _ _ _ _ _  y  
270/100= 62/y => y= 62x100/270=6200/270= 22,96% P

270 g _ _ _ _ _ _ _ 128g O
100 g _ _ _ _ _ _ _ z

270/100 = 128/z => z=128x100/270 = 12800/270 = 47.41% 

Al(Oh)3

M Al(Oh)2 =A Al+ 3xA O + 3xA H
               = 27+ 3x16 + 3x1
               = 27+48+3
               =78

 78 g _ _ _ _ _ _ 27 g Al 
100 g _ _ _ _ _ _ x
68/100 = 27/x  => x = 100x27/78 = 2700/78 = 34,62% Al

78 g _ _ _ _ _ _ 48 g O
100g _ _ _ _ _ _ y
78/100 = 48/y => y= 100x48/78= 4800/78 =61,53 %

78g _ _ _ _ _3 g H
100g _ _ _ _ _ z  

78/100 = 3/z => z= 100x3/78 = 300/78 = 3.85%
Aleluia! Am terminat :)) O_O