In the reaction Mg(s) + Br2() → MgBrz(s), what should be the coefficient for Br2?

A. 2
B. 4
C. 1
D. 3

1

Explanation:

Chemical equation:

Mg + Br₂  →  MgBr₂

Balanced chemical equation:

Mg + Br₂  →  MgBr₂

Left hand side                         Right hand side

Mg = 1                                         Mg = 1            

Br = 2                                          Br = 2

There are one Mg and 2 Br atoms on both side of equation thus this equation is balanced. Thus coefficient with bromine is 1.

Mg is present in group 2 it loses two valance electrons and get +2 oxidation state. Bromine is present in group 17 have 7 valence electrons. Thus one bromine atom need only one electron to complete the octet that's why two bromine atoms will attached with one magnesium atom to cancel the charge +2 and make the compound neutral.

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !

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