Answer:
O a 2 in front of hydrochloric acid
Explanation:
the given reaction is :-
=》Zn + 2 HCL -> ZnCl2 + H2
since, mass can't be created or destroy, so number of hydrogen atoms in the reaction should be equal in product as in reaction.
so, there is 2 hydrogen in product hence there are two hydrogen in the reactants also.
it is showed in the reaction by putting a 2 in front of hydrochloric acid ( HCl ).
Answer : The concentration of 
at equilibrium is 0 M.
Solution : Given,
Concentration of = 0.0200 M
Concentration of 
= 1.00 M
The given equilibrium reaction is,
![Fe^{3+}(aq)+3C_2O_4^{2-}(aq)\rightleftharpoons [Fe(C_2O_4)_3]^{3-}(aq)](https://tex.z-dn.net/?f=Fe%5E%7B3%2B%7D%28aq%29%2B3C_2O_4%5E%7B2-%7D%28aq%29%5Crightleftharpoons%20%5BFe%28C_2O_4%29_3%5D%5E%7B3-%7D%28aq%29)
Initially conc. 0.02 1.00 0
At eqm. (0.02-x) (1.00-3x) x
The expression of 
will be,
![K_c=\frac{[[Fe(C_2O_4)_3]^{3-}]}{[C_2O_4^{2-}]^3[Fe^{3+}]}](https://tex.z-dn.net/?f=K_c%3D%5Cfrac%7B%5B%5BFe%28C_2O_4%29_3%5D%5E%7B3-%7D%5D%7D%7B%5BC_2O_4%5E%7B2-%7D%5D%5E3%5BFe%5E%7B3%2B%7D%5D%7D)
By solving the term, we get:
Concentration of at equilibrium = 0.02 - x = 0.02 - 0.02 = 0 M
Therefore, the concentration of at equilibrium is 0 M.
What are you trying to ask
Calcium has only two valence electrons in its shell. In order to agree with the octet rule it bonds with oxygen which has 6 valence electrons and with hydrogen which has 1 valence electron. Hope this answers the question. Have a nice day.
