Module 3.2- Enthalpy Change Flashcards
What is enthalpy??
The heat content stored in a chemical system
What is the law of conservation of energy??
Energy can’t be created or destroyed, but can be converted from one form to another
What is the sign for enthalpy change??
🔼H = change in H(enthalpy)
What sign do exothermic and endothermic enthalpy changes have??
Exothermic= negative enthalpy change, energy is lost from the system
Endothermic= positive enthalpy change, energy is gained
How do you work out enthalpy change?
Enthalpy of products - enthalpy of reactants
Where do reacts and products go on an exothermic reaction diagram with energy on the Y axis??
The reactants go above the products because when they react, energy is lost and the products have less energy than the reactants
Why doesn’t a gas tap just explode when opened in a room??
There is not enough energy for the gas particles to react- it needs activation energy
What is activation energy??
The minimum energy required for colliding particles to react
Why do reactions needs activation energy??
So there’s enough energy to break old bonds, allowing new ones to form
How do you show activation energy on an exothermic reaction diagram?
Draw the reactions, then draw a hump that goes above it then drops back down to the products. The reaction gives out heat, but heat is put in to provide the activation energy
