Mrs. Howland Chemistry 10 Rev. April 2016

Learners will be able to … Describe atmospheric pressure and explain how a barometer works Describe Dalton’s Law of Partial Pressures Determine partial pressure of gases from data List properties of gases Differentiate among the behavior of particles in solids, liquids, and gases Explain the effects of temperature, pressure, and volume changes on the behavior of gas particles Define kinetic energy in terms of velocity and mass of particles Relate molecular motion to temperature and molecular collisions to pressure Define standard temperature and pressure Identify and convert between units of temperature and pressure Define molar volume State the written and mathematical expression of two gas laws, Boyle’s Law and Charles Law Provide detailed real-life or laboratory examples of Boyle’s Law and Charles’ Law Use the Common Gas Law to solve problems involving temperature, pressure, and volume

ALL MATTER is made up of tiny particles (ATOMS) that are constantly moving 3 MAIN STATES OF MATTER: Solid Liquid Gas (plasma)

Particles move at different speeds in each state of matter Increased energy (often in form of heat) will increase movement of particles

No fixed shape; no fixed volume Lots of empty space between particles High kinetic energy Expand to fit the size of their container Particles diffuse to spread out evenly in container Easily compressed Weak attractions

Particles in constant, random motion Move in straight line until collisions with other particles or side of container Particles much smaller than space between particles (most gas volume is empty space and therefore negligible)

No forces of attraction between particles or particles and container Collisions are elastic (energy is not lost) Average kinetic energy depends on temperature

Temperature Pressure Volume Amount (moles)

Temperature = Measurement of heat…or how fast the particles are moving Pressure = Force per unit area (exerted by gas particles’ collisions with walls of container) Amount = Moles (amount of particles), abbreviated ‘n’ Volume = Three-dimensional space inside the container holding the gas. ~ How much space does the gas take up?

°F (Fahrenheit) °C (Celsius) K (Kelvin)  We will ALWAYS use KELVIN for gas laws!! To convert between Celsius and Kelvin:

atm = atmosphere mmHg = millimeters of mercury Torr = another name for mmHg Pa = Pascal andkPa = kilopascal

How? See the example below: Pressure is measured as758.7 mm Hg. What is this pressure in atm? mm Hg x 1 atm = 0.99 atm 760 mm Hg

1)1820 mmHg = ? atm 1)6.2 atm = ? torr 1)1159 torr = ? mmHg

Torricelli Barometer = Instrument that uses mercury (Hg) to measure atmospheric pressure (like liquid in a drinking straw!) Pressure of Hg pushes down until it balances the force of atmosphere (pushes up)

Aneroid barometer uses a cell with small amount of air, lever, and pointer Face of instrument gives pressure measurement Pressure inside cell raises or lowers lever, which moves the dial VIDEO:

Dalton’s Law of Partial Pressure States that the total pressure in a MIXTURE of gases is the SUM of the partial pressure of each gas

A container holds three gases: oxygen, carbon dioxide, and helium. The partial pressures of the three gases are 2.00 atm, 3.00 atm, and 4.00 atm, respectively. What is the total pressure inside the container?

In gases, the measureable properties have relationships among each other Some properties (variables) will change other properties (variables) For example, THINK ABOUT IT … what happens if you leave your basketball outside in the winter? VIDEO:

Same # of gas atoms! This means the moles of gas remains constant

Charles Boyle studied the relationship between pressure, p, and volume, V, in the mid-1600s Boyle determined that for the same amount of a gas at constant temperature, there is an inverse relationship between volume and pressure:  when one INCREASES, the other DECREASES pressure volume

Jacques Charles studied the relationship volume, V, and temperature, T, around the turn of the 19 th century DIRECT RELATIONSHIP between V and T With the same amount of gas, as the volume INCRASES the temperature also INCREASES. If the temperature decreases than the volume also decreases. volume temperature

Joseph Gay-Lussac studied the temperature, T, and pressure, P, in the early 19 th century DIRECT RELATIONSHIP between P and T With the same amount of gas and CONSTANT VOLUME, as the temperature INCRASES, the pressure also INCREASES If the temperature decreases than the volume also decreases. Pressure temperature

With increasing temperature, particles move faster (increased kinetic energy) Faster movement results in more collisions with wall of container, increasing the pressure MUST HAVE CONSTANT VOLUME!!

When temperature and moles are constant, we can use the formula to solve for one of the variables V or P

These formulas are used to PREDICT or DETERMINE how gases have changed. ‘BEFORE’‘AFTER’

When pressure and moles are constant, we can use the formula to solve for one of the variables V or T CROSS-MULTIPLY to solve, OR…

When and moles and volume are constant, we can use the formula to solve for one of the variables P or T

twice as many molecules Equal volumes of gases at the same T and P have the same number of molecules. V and n are directly related (‘n’ represents moles!)

You don’t HAVE to remember all 3 laws to do gas law problems! (yayyy!! ) All are related, so they can be combined in a SINGLE FORMULA: REMEMBER: T is in Kelvin!!

Cover up the variable that is CONSTANT and you automatically get the gas law you need! REMEMBER: T is in Kelvin!! Need help? Try this video:

Occasionally, you will come across a problem that states “standard temperature and pressure”, or “STP” What does this mean?

Remember the mole map? At STP, there are 22.4 L of gas and 1 mole of particles