The energy that is
essential to break one C-H bond is 414 kJ/mol. Since, there are four C-H bonds
in CH4, the energy Δ HCH4 for
breaking all the bonds is calculated as Δ HCH4 = 4 x bond energy of C-H bond. By
multiplying the 4 with the 414 kJ/mol you can get the answer of 1656 kJ/mol CH4
molecules.
The question is incomplete. The complete question is:
Calcium Carbide (CaC₂) is an unusual substance that contains a carbon anion (C₂²⁻). The reaction with water involves several steps that occur in rapid succession. CaC2 is a salt (notice that its name is similar to sodium chloride). When a salt dissolves in water, ions leave the crystal lattice and enter the aqueous (aq) solution. Write the relevant balanced chemical equation for the dissolution of CaC₂, in water.
Answer:
CaC₂(s) + 2H₂O(l) → Ca(OH)₂(aq) + C₂H₂(aq)
Explanation:
When a salt dissolves in water, it dissociates in its ions. In the Calcium Carbide, the cation is Ca⁺² and the anion is C₂²⁻, so the reaction is:
CaC₂(s) + 2H₂O(l) → Ca(OH)₂(aq) + C₂H₂(aq)
The base Ca(OH)₂ is soluble, so it will dissociate at Ca⁺ and OH⁻, but the C₂H₂ is stable and doesn't dissociate in the solution.
