Chapter 14: Expansion and Temperature Pg 303 - 322

Linear Thermal Expansion of Solids Most solids get bigger when heated and smaller when cooled. Water is the exception, getting largest when at 4 degrees Celsius. That’s why fish don’t freeze.

Cont We can measure the expansion (growing) of solids by using a length-temperature graph. We can also measure mathematically, using an equation similar to y = mx +b

Cont The change of the length of the wire is equal to the constant times the original length of the wire times the temperature. Constant will be different for each solid and is determined by a chart. Coefficient of linear expansion is fish

Linear expansion Useful in thermostats – the bimetallic strip of copper and iron expands at different rates in different temperatures, causing the curling of the metal in specific ways, controlling what you read as the temperature (see video)

Thermal Volume Expansion of Solids Volume of a solid after it is heated. Used for solids with shape that do not expand in a linear fashion

Thermal expansion of liquids and gasses Liquids are more sensitive to temperature than solids Use the same formula as solids for liquids Gases tend to expand as far as their containers will allow, so the temperature must be raised substantially before any change will be noticed

Conversion of Temperatures

Charles’s Law Use to show the relationship between volume and temperature (use Kelvin temperature)

Boyle’s Law Use to show the relationship between volume and pressure (can use atm or torr or mm Hg for pressure)

Gay-Lussac’s Law Used to show relationship between pressure and temperature

Combined Gas Law Used to show the relationship between volume, temperature, and pressure. Can be used as long quantity of gas is known

Ideal Gas Law Ideal gas law used when nothing is known or constant – used for real-world situations R is universal gas constant (8.315 J/(K times mol)

STP Standard Temperature and Pressure (STP) Temperature: 273.15 K Pressure: 101.3 kPa or 1 atm

Van der Waals gases Van der Waals made an equation that can be used when volume and pressure do not interact as they should according to the ideal gas laws Laws that follow van der Waal’s law are called van der Waals gases See next slide

Van der Waals formula

Homework Page 323 Q1,2,5,12-16, 26-33