Question

Butane combusts in the atmosphere and releases heat:2C4H10(g) + 13 O2(g) ---> 8 CO2(g) + 10 H2O(g)The signs of the values for ΔG, ΔH, and ΔS for this reaction would be+, +, -+, -, --, -, +-, +, +

Answer 1

Answer:$\Delta G$: -ve

$\Delta H$ : -ve,

$\Delta S$ : +ve

Explanation:

Endothermic reactions are those in which heat is absorbed by the system and exothermic reactions are those in which heat is released by the system.

$\Delta H$ for Endothermic reaction is positive and  $\Delta H$ for Exothermic reaction is negative.

Entropy is the measure of randomness or disorder of a system. If a system moves from  an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

$\Delta S$ is positive when randomness increases and $\Delta S$ is negative when randomness decreases.

$2C_4H_{10}(g)+13O_2(g)\rightarrow 8CO_2(g)+10H_2O(g)$

As 15 moles of gaseous reactants are changing into 18 moles of gaseous products, randomness is increasing and thus $\Delta S$ is positive.

Using Gibbs Helmholtz equation:

$\Delta G=\Delta H-T\Delta S$

$\Delta G=(-ve)-T(+ve)$

$\Delta G=(-ve)(-ve)=-ve$

Thus $\Delta H$ is negative , $\Delta S$ is positive and $\Delta G$ is negative.