Entropy, Enthalpy, and Free Energy

Delta H is negative indicates

• reaction is exothermic

• reaction is endothermic

• reaction is spontaneous

• reaction is not spontaneous

Tags

NGSS.HS-PS3-1

Delta S is negative indicates

• enthalpy increases

• enthalpy decreases

• entropy decreases

• entropy increases

Delta G is negative indicates

• reaction is exothermic

• reaction is endothermic

• reaction is spontaneous

• reaction is not spontaneous

A phase change from solid --> liquid

• shows a decrease in entropy

• shows an increase in entropy

• is exothermic

• is endothermic

A phase change from gas --> liquid

• shows a decrease in entropy

• shows an increase in entropy

• is exothermic

• is endothermic

Which of these would ALWAYS indicate a process is spontaneous?

•  $\Delta H\ is\ +\ \Delta S\ is\ +$  

•  $\Delta H\ is\ -\ \Delta S\ is\ -$  

•  $\Delta H\ is\ +\ \Delta S\ is\ -$  

•  $\Delta H\ is\ -\ \Delta S\ is\ +$  

If the enthalpy of the products > reactants then this reaction is said to be

• spontaneous

• endothermic

• exothermic

• unlikely

Tags

NGSS.HS-PS1-4

The reaction $2\ H_{2\left(g\right)}+O_{2\left(g\right)}\rightarrow\ 2\ H_2O_{\left(g\right)}$  shows 

• no change in entropy

• an increase in entropy

• a decrease in entropy

According to Hess' law, if you reverse a reaction

• the sign of delta H must flip

• you do not change the delta H sign

• you must multiply the delta H value by 2

• you must divide the value of delta H by 2

According to Hess' law the reaction pathway's effect on reaction enthalpy is that it

• doesn't matter

• affects the overall enthalpy change

• can only have one step

• can't have more steps than reactants