FIRST LAW
To understand how energy moves during a chemical reaction, we
need to look at two important parts: the system and its surroundings.
Figure 1: System vs Surroundings
System: This is the specific part of the universe we're focused on.
For example, if we're watching a chemical reaction happen in a
beaker, the chemicals inside the beaker are the system.
Surroundings: Everything else around the system is the
surroundings. In our beaker example, this includes the air, the
table the beaker sits on, and even the room itself.
There are three kinds of systems are important:
Figure 2: Three different kinds of systems
1. Open System - Can exchange both matter and energy with its
surroundings.
2. Closed System - Can exchange energy with its surroundings but
not matter.
3. Isolated System - Does not exchange either energy or matter
with its surroundings.
, FIRST LAW
State function - Is a property that depends only on the current state
of a system, not on how the system arrived at that state. Only cares
about initial and final.
Path function - Is a property whose value depends on the path taken
to reach a particular state in a system. Path functions are associated
with the process or journey that the system undergoes from one state
to another, rather than just the initial and final states themselves.
To understand this better, let us look at this example
Figure 3: Path A using an elevator. Path B manually pushing by a
person to get to the top.
To reach at the top, you can either take path A, using an elevator or
path B by manually pushing it. Once at the top, the potential energy
remains unchanged regardless of the path chosen but the amount of
work differ greatly in path B. Therefore, work is a path function—its
magnitude depend on the path taken. In contrast, potential energy is a
state function—it is independent of the path taken whether you choose
path A or path B, it does not matter, potential energy would still be the
same.
Examples of state functions include temperature, pressure, density,
volume, Gibb's free energy, enthalpy, internal energy, and entropy.
Path functions are work and heat.
To understand how energy moves during a chemical reaction, we
need to look at two important parts: the system and its surroundings.
Figure 1: System vs Surroundings
System: This is the specific part of the universe we're focused on.
For example, if we're watching a chemical reaction happen in a
beaker, the chemicals inside the beaker are the system.
Surroundings: Everything else around the system is the
surroundings. In our beaker example, this includes the air, the
table the beaker sits on, and even the room itself.
There are three kinds of systems are important:
Figure 2: Three different kinds of systems
1. Open System - Can exchange both matter and energy with its
surroundings.
2. Closed System - Can exchange energy with its surroundings but
not matter.
3. Isolated System - Does not exchange either energy or matter
with its surroundings.
, FIRST LAW
State function - Is a property that depends only on the current state
of a system, not on how the system arrived at that state. Only cares
about initial and final.
Path function - Is a property whose value depends on the path taken
to reach a particular state in a system. Path functions are associated
with the process or journey that the system undergoes from one state
to another, rather than just the initial and final states themselves.
To understand this better, let us look at this example
Figure 3: Path A using an elevator. Path B manually pushing by a
person to get to the top.
To reach at the top, you can either take path A, using an elevator or
path B by manually pushing it. Once at the top, the potential energy
remains unchanged regardless of the path chosen but the amount of
work differ greatly in path B. Therefore, work is a path function—its
magnitude depend on the path taken. In contrast, potential energy is a
state function—it is independent of the path taken whether you choose
path A or path B, it does not matter, potential energy would still be the
same.
Examples of state functions include temperature, pressure, density,
volume, Gibb's free energy, enthalpy, internal energy, and entropy.
Path functions are work and heat.
