is this true or false? i think its false because isnt it spontaneous if its positive
When (triangle i think its called delta) H for a reaction is large and positive, the reaction is not expected to be spontaneous.
change of heat, yeah then it requires heat which means it should be non-spontaneous . ..
Delta H is positive, the reaction is endothermic therefore not spontaneous.
delta G = delta H -TdeltaS.
Generally, but not always, if delta H is negative, then delta G is more likely to be negative, and the reaction will be spontaneous. But delta H can be + and the temperature can be high enough to make the TdeltaS term override the + delta H and delta G can be negative and the reaction spontaneous.
To determine whether a reaction is expected to be spontaneous or not, you can look at the sign of ΔH (enthalpy change) and ΔS (entropy change).
If ΔH is large and positive, it means that the reaction is endothermic, i.e., it absorbs heat from its surroundings. In this case, the reactants have lower energy than the products. Generally, an endothermic reaction would not be expected to be spontaneous because it requires an input of energy to proceed.
On the other hand, if ΔH is large and negative (exothermic reaction), it means that the reaction releases heat to its surroundings. In this case, the reactants have higher energy than the products. An exothermic reaction with a large and negative ΔH is more likely to be spontaneous because it releases energy and can occur without an external energy source.
However, it's important to consider ΔS as well. ΔS represents the change in entropy (disorder) of the system. Generally, an increase in entropy favors spontaneity. So, even if ΔH is positive, if ΔS is large and positive, the reaction may still be spontaneous because the increase in entropy can overcome the endothermic nature of the reaction.
In summary, a reaction with a large and positive ΔH is not expected to be spontaneous, but other factors like ΔS can influence the spontaneity of the reaction.