Answer: The volume of hydrogen gas produced will be, 12.4 L
Explanation : Given,
Mass of
= 54.219 g
Number of atoms of
= ![7.179\times 10^{23}](https://tex.z-dn.net/?f=7.179%5Ctimes%2010%5E%7B23%7D)
Molar mass of
= 98 g/mol
First we have to calculate the moles of
and
.
![\text{Moles of }H_3PO_4=\frac{\text{Given mass }H_3PO_4}{\text{Molar mass }H_3PO_4}](https://tex.z-dn.net/?f=%5Ctext%7BMoles%20of%20%7DH_3PO_4%3D%5Cfrac%7B%5Ctext%7BGiven%20mass%20%7DH_3PO_4%7D%7B%5Ctext%7BMolar%20mass%20%7DH_3PO_4%7D)
![\text{Moles of }H_3PO_4=\frac{54.219g}{98g/mol}=0.553mol](https://tex.z-dn.net/?f=%5Ctext%7BMoles%20of%20%7DH_3PO_4%3D%5Cfrac%7B54.219g%7D%7B98g%2Fmol%7D%3D0.553mol)
and,
![\text{Moles of }Mg=\frac{7.179\times 10^{23}}{6.022\times 10^{23}}=1.19mol](https://tex.z-dn.net/?f=%5Ctext%7BMoles%20of%20%7DMg%3D%5Cfrac%7B7.179%5Ctimes%2010%5E%7B23%7D%7D%7B6.022%5Ctimes%2010%5E%7B23%7D%7D%3D1.19mol)
Now we have to calculate the limiting and excess reagent.
The balanced chemical equation is:
![3Mg+2H_3PO_4\rightarrow Mg(PO_4)_2+3H_2](https://tex.z-dn.net/?f=3Mg%2B2H_3PO_4%5Crightarrow%20Mg%28PO_4%29_2%2B3H_2)
From the balanced reaction we conclude that
As, 3 mole of
react with 2 mole of ![H_3PO_4](https://tex.z-dn.net/?f=H_3PO_4)
So, 0.553 moles of
react with
moles of ![H_3PO_4](https://tex.z-dn.net/?f=H_3PO_4)
From this we conclude that,
is an excess reagent because the given moles are greater than the required moles and
is a limiting reagent and it limits the formation of product.
Now we have to calculate the moles of ![H_2](https://tex.z-dn.net/?f=H_2)
From the reaction, we conclude that
As, 3 mole of
react to give 3 mole of ![H_2](https://tex.z-dn.net/?f=H_2)
So, 0.553 mole of
react to give 0.553 mole of ![H_2](https://tex.z-dn.net/?f=H_2)
Now we have to calculate the volume of
gas at STP.
As we know that, 1 mole of substance occupies 22.4 L volume of gas.
As, 1 mole of hydrogen gas occupies 22.4 L volume of hydrogen gas
So, 0.553 mole of hydrogen gas occupies
volume of hydrogen gas
Therefore, the volume of hydrogen gas produced will be, 12.4 L