Gases -
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Transcript of Gases -
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GASES - UNIT WRAP-UP
Review Practice
Stoichiometry
Vapor Pressure
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Agenda: 4/27 • Warm-up: Ideal gas law video• Choosing the right gas law formula
• Practice Problems
• Gas Stoichiometry • You Tube Video • Practice problems
• Dalton’s Law of Partial Pressure
• States of Matter - Changes • How do the states of matter change? Why? • Sorting Terms• Read States of Change & write a graphic organizer
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Ideal Gas Law: Discovery Ed video
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Which formula to use?
• Combined Gas Law • Ideal Gas Law
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Practice: Ideal & Combined Gas Laws1. If four moles of a gas at a pressure of 5.4 atmospheres
have a volume of 120 liters, what is the temperature?
2. If I initially have a gas with a pressure of 84 kPa and a temperature of 35 and then I heat it to an additional ℃230 , what will be the new pressure? (Assume the ℃volume of the container is constant.)
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• 3. My car has an internal volume of 2600 liters. If the sun heats the care from a temperature of 20 to a temperature ℃of 55 , what will the pressure inside my car be? (Assume ℃that the initial pressure was 760 mm Hg.)
• 4. How many moles of gas (air) are in my car in problem #3?
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• 5. A toy balloon which is filled with air has an internal pressure of 1.25 atm and a volume of 2.5 L. If I take the balloon to the bottom of the ocean where the pressure is 95 atm, what will be the new volume?
• 6. How many moles of gas does the toy balloon hold at 1.25 atm, 2.5 L, and 285 K?
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Stoichiometry – with gases• You Tube Video
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Gas Stoichiometry• N₂ +3H₂→ 2NH₃What is the volume of NH₃ at STP if produced if 25.0 g of N₂ is reacted with an excess of H₂?
2KClO₃→ 2KCl + 3O₂If 5.0 g of KClO₃ is decomposed, what volume of O₂ will be produced at STP?
How many grams of KCl are produced in the above problem?
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• Zn + 2HCl → ZnCl₂ + H₂• What volume of hydrogen at STP is produced when 2.5 g of zinc react with an excess of hydrochloric acid?
• 2AlCl₃→ 2Al + 3Cl₂• If 10.0 g of aluminum chloride are decomposed, how many molecules of chloride are produced?
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Dalton’s Law of Partial Pressures
V and T are
constant
P1 P2 Ptotal = P1 + P2
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Dalton’s Law of Partial Pressure
• Mixture of gases (no reaction takes place)
• What is the total blood gas pressure for a person having CO₂ partial pressure of 60.1 mm Hg and an O₂ partial pressure of 39.2 mm Hg?
Ptotal = P₁+P₂+P₃+Petc.
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Avogadro’s Law
V a number of moles (n)
V = constant x n
V1/n1 = V2/n2
Constant temperatureConstant pressure
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How are gases related to solids and liquids?
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Characteristics of Solids, Liquids & Gases
• Sort the terms into 3 columns: S, L, G• (Hint: Look for 3 cards with similar wording and determine which
best fits solid, liquid or gas)
• Solid Liquid Gas
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Gases vs. Liquids & Solids• Read Study Guide pp. 2 - Changes of State• Prepare a graphic organizer to show the changes of state
and why they happen• Include terms: solid, liquid, gas, heat, heat energy, melting,
boiling, evaporation, forces of attraction, bonds, cool
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Most substances, like water, can exist in all three states.
A cloud is made of water vapor, a type of gas.
An iceberg is made of water in solid form.
This glass contains liquid water.
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How do solids and liquids differ from gases?
HOW DOES A SUBSTANCE BECOME A GAS?
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Changing States (Phase changes)
Solid GasLiquid
Increase Thermal Energy (Heat up)
Decrease Thermal Energy (Cool off)
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Melting point
• Melting - change from solid to liquid• Melting point - SPECIFIC temperature when melting occurs.
• Each pure substance has a SPECIFIC melting point.• Examples:• M.P. of Water = 0°C (32°F) • M.P. of Nitrogen = -209.9 °C (-345.81998 °F)• M.P. of Silver = 961.93 °C (1763.474 °F) • M.P. of Carbon = 3500.0 °C (6332.0 °F)
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Melting Point
• Particles of a solid vibrate so fast that they break free from their fixed positions.
Solid Liquid
Increasing Thermal Energy
Melting point
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Vaporization
• Vaporization – change from liquid to gas• Vaporization happens when particles in a liquid gain
enough energy to form a gas.
GasLiquid
Increasing Thermal Energy
Boiling point
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Two Kinds of Vaporization
• Evaporation – vaporization that takes place only on the surface of the liquid
• Boiling – when a liquid changes to a gas BELOW its surface as well as above.
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Boiling Point
• Boiling Point – temperature at which a liquid boils• Each pure substance has a SPECIFIC boiling point.
• Examples:• B.P. of Water = 100°C (212°F) • B.P. of Nitrogen = -195.79 °C (-320.42 °F)• B.P. of Silver = 2162 °C (3924 °F) • B.P. of Carbon = 4027 °C (7281 °F)
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Boiling Point and Melting Point
-150
-100
-50
0
50
100
150
200WATER – H20
time
Tem
per
atu
re Melting point
Boiling point
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As heat increases,
Thermal Energy Added
Tem
pera
ture
Standard Curve for all Substances
• As heat decreases,
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WHAT ARE THE CHANGES OF STATE?
GAS
SOLID LIQUID
Deposition
Sublimatio
n
Boiling / Evaporation
Condensation
Freezing
Melting
Which are endothermic?
Which are exothermic?
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Energy and change of state (phase changes)
Energy levelEnergy changePhase changesMP/BP
Entropy= degree of disorder
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Vapor Pressure
The vapor pressure is the pressure measured when there is an equilibrium between the gas and liquid phases. The rates of condensation and vaporization
are equal.
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Vapor pressure • http://www.chem.purdue.edu/gchelp/liquids/vpress.html
• Discovery Ed video
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Resources for S, L, G• http://www.kentchemistry.com/links/Matter/
HeatingCurve.htm