`color{red}{7}`

`-`Phần trăm của các nguyên tố là:

$CH_{4}$ 

`%C`=`12/16`× `100%=75%`

`%H`= `100%-75%=25%`

$CaCO{3}$ 

`%Ca=40/100× 100%=40%`

`%C=12/100 ×100%=12%`

`%O=100%-40%-12%=48%`

$H_{2}$`S` 

`%H=2/34× 100%≈ 5,88%`

`%S≈ 94,12%`

$H_{2}$$SO_{4}$ 

`%H=2/98× 100%≈ 2,04%`

`%S=32/98 ×100% ≈32,65%`

`%O≈ 47,53%`

$\%Mg = \frac{24}{120} ×100% = 20\%$

$\%S = \frac{32}{120} ×100% ≈26,67\%$

$\%O≈ 53,33\%$

$\%Na = \frac{23}{58,5}  100%≈ 39,32%$

$\%Cl≈ 60,68\%$

$m_{Al}$=$\frac{75× 59}{100}$ `46` amu`=>` `x=46/23=2` 

$m_{S}$=`78-46=32` amu`=> y=32/32=1` 

CTHH $Na_{2}$`S` 

$m_{O}$=$\frac{142× 56,34}{100}$ `80` amu `=> 80/16=5` 

$m_{P}$=`142-80=62`amu`=>x=62/31=2` 

CTHH$P_{2}$$O_{5}$ 

`color{blue}{tramy7210}`