__Tutorial – Charles’ Law__** (Std 4c)**

Read through this tutorial
very carefully. It has almost everything
that needs to be done in the most difficult of Charles’ Law problems, and goes
through the logic of why each step is required.
I hope

this helps!!!!

With
__Boyle’s Law__**pressure** and **volume** were ** inversely**
proportional. That means that as one

increases
the other decreases.

**PV
= k** **k** is a constant

With
__Charles’ Law__**temperature** and **volume **are ** directly** proportional. That means that as

temperature
increase, volume must increase also.

**V **

** ---- =
b b is** a constant

** T**

**Using Charles’ Law:**

**V _{1}**

** --- =
--- **V_{2} – ending volume

** T**_{1}**T**** _{2}** T

** **T_{2} – ending temperature in __Kelvins____ only__

As with Boyle’s law, the **unit of measure** for **Volume**
** must be the same for both V_{1} and V_{2}.** Another important thing to remember is that

**Example:**

We start with
temperature at 25 °C and an end with a temperature of 58 °C. The

volume
starts at 75 ml. What is the final
volume?

**Solution:**

T_{1} = 25 °C T_{2}
= 58 °C V_{1}
= 75 ml and V_{2} = unknown

We cannot use Charles’ Law until the temperatures are
in Kelvins.
Remember that:

**°****C + 273 = K** which also
means that **K = ****°****C - 273**

25 °C + 273 °C = 298 K = T_{1}

58 °C + 273 °C = 331 K = T_{2}

Now we can use these
temperatures in Charles’ Law as follows:

75 ml T_{2}

-------- =
---------

298 K 331 K

The unit of measure K crosses out on both sides of the = sign. The unit of measure

left
is ml. To finish off the math,
multiply 75 ml x 331 and then divide your answer

by
298:
**Answer 83.3 ml = T**_{2}