Find ΔH for: BaCO3 (s) → BaO (s)+ CO2 (g) given 2 Ba (s) + O2 (g) → 2 BaO (s) ΔH = – 1107.0 kJ Ba (s) + CO2 (g) + ½ O2 (g) → BaCO3 (s) ΔH = – 822.5 kJ

The answer to your question is ΔH = 269 kJ

Explanation:

Change the sense of the third reaction

           BaCO₃(s)  ⇒  Ba(s)  + CO₂(g)  + 1/2O₂(g)       ΔH = 822.5 kJ

Divide the second reaction by 2

           Ba(s)   +  1/2O₂(g)  ⇒  BaO(s)                         ΔH = -553.5 KJ

Add both reactions and cancel reactants and products

            BaCO₃(s) ⇒  BaO (s)  +  CO₂ (g)                  ΔH = 269  (822.5 - 553.5)

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.