Question

The question goes as: Determine whether each of the following isexothermic or endothermic and indicate the sign of (Delta sign) H.

a. Dry ice evaporating - I believe is endothermic?

b. a sparkler burning- I believe is exothermic?

c. the reaction that occurs in a chemical cold pack often usedto ice athletic injuries - I believe is exothermic?

Answer 1

First let me have you a general idea if heat is given by thesystem then ΔH is negative and the reaction isexothermic

if heat is absorbed by the system then ΔH is positive andthe reaction is endothermic.

a. Dry ice evaporating -

to evaporate a dry ice we need to supply heat so heat isabsorbed by the system so its endothermic

reaction and here, ΔH is having positive value.

b. a sparkler burning-

when a sparkler is burning heat is given out to the system sothe reaction is exothermic and so,

ΔH value is negative.

c. the reaction that occurs in a chemical cold pack often usedto ice athletic injuries -

the chemical cold pack is used it it absorbs heat so if weconsider it a system then it absorbs heat and so the reactionis endothermic and ΔH value is positive.