This equation is not balanced. Click on the coefficient we should change first.
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 The coefficient we should change first is for .

Explanation:

The given reaction equation is as follows.

Here, number of atoms present on reactant side are as follows.

Number of atoms present on the product side are as follows.

To balance this equation, multiply Al by 2 and by 3 on reactant side. Also, multiply by 2 and Ni by 3 on the product side.

Hence, the equation can be rewritten as follows.

Now, number of atoms present on reactant side are as follows.

Number of atoms present on product side are as follows.

Since, the atoms on both reactant and product side are same. Hence, it is now a balanced chemical equation.

Thus, we can conclude that the coefficient we should change first is for .

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.

the answer is barium and copper bromide