Enthalpy chnge

- for now summary notes but to edit after exams

The following reaction is taking place in a beaker, without a lid:

Which of the following are a part of the SYSTEM or SURROUNDINGS?

• aqueous solution

• beaker

• gas phase

• products

• reactants

  • air containing O2

System:

• gas phase→ tells us the state that oxygen is in therfore how they react

• products

• reactants

Surroundings

• aqueous solution → water is not created or use and is just a ‘medium’ for the reactants to dissolve in

• beaker

  • air containing O2

When a reaction happens at a constant pressure, it means that the pressure…

the surroundings exert on the system doesn’t change (pressure inside the container is the same as pressure exerted onto the container from outissed ad the reaction is in a closed system and has the same amount of molecules/pressure beofre and after the reaction )

As a reaction progresses……flows between the system and the surroundings.

If heat energy flows from the system to the surroundings, the reaction system ………..heat energy.

If heat energy flows from the surroundings to the system, the reaction system …….heat energy.

• heat energy

• gives out→ making surrousings hotter

• takes in → making suroundings colder

A strip of magnesium is held in the flame of a Bunsen burner. It burns brightly to produce magnesium oxide, according to the equation:

2Mg (s)+O2(g)→2MgO (s)2Mg (s)+O2​ (g)→2MgO (s)

Identify the components of the system and the surroundings in this reaction.

- Bunsen burner flame, tongs,magnesium,magnesium oxide, oxygen in the air, nitrogen in the air

SYSTEM

• Mg

• MgO

SURROUNDINGS

• Tongs

• N₂

BOTH

• Bunsen burner flame

• Oxygen in the air ( O