Explanation:
The given chemical equation is as follows.
[tex]H_{2}SO_{4} + NaCN \rightarrow HCN + Na_{2}SO_{4}[/tex]
Number of reactant atoms are as follows.
Number of product atoms are as follows.
Thus, in order to balance the equation, multiply NaCN by 2 on the reactant side and multiply HCN by 2 on the product side. Therefore, the balanced chemical equation will be as follows.
[tex]H_{2}SO_{4} +2NaCN \rightarrow 2HCN + Na_{2}SO_{4}[/tex]
Hence, we need [tex]2 \times 3.6[/tex] = 7.2 moles of NaCN to react completely with 3.6 moles of [tex]H_{2}SO_{4}[/tex].