By using the following reactions, calculate the heat of combustion of pentane: C5H12 (g) + 8O2 (g) → 5CO2 (g) + 6H2O (l).

C (s) + O2 (g) → CO2 (g), ΔH = –395 kJ
H2 (g) + 1/2O2 (g) → H2O (l), ΔH = –285 kJ
5C (s) + 6H2 (g) → C5H12 (g), ΔH = –147 kJ

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

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

answer:

the reaction is type of combination reaction.

explanation:

on the product side, there are 2 molecules of bonded to fe   which means one atom of fe are combined two molecules of . so, balanced chemical equation becomes :

this reaction follows the reaction type of combination reaction. a combination reaction is defined as chemical reaction in which reactants combines together to form a single product.

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