Name: gas pressure in mixtures: partial pressures
Uploaded: 2020-09-03T13:38:26.000Z
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K12 Standards

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NC K-12 Science Standard Course of Study

9-12

Chemistry

Energy

PS.Chm.7.3

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Mixtures of Gases: Dalton's Law of Partial Pressures and Mole Fractions

ضغط الغاز النقي هو مجموعه من الاصطدامات الجزيئية بين جسيماته والأسطح المحيطة. عينة غاز تحتوي على عدد أقل من الجسيمات في حجم معين،تمارس ضغطًا أقل من العينة ذات الجسيمات الأكثر في نفس الحجم. لكن ما هو ضغط خليط الغازات المختلفة؟لخليط غاز متعدد المكونات،الضغط هو مجموع الاصطدامات بين جميع جزيئات الغاز.ويفترض أن كل مكون في الخليط يمارس ضغطه المستقل عن الغازات الأخرى الموجوده. الضغط من أي مكون فردي يسمى بالضغط الجزئي. الضغط الكلي لخليط الغاز المثالي يساوي مجموع الضغوط الجزئية لمكوناته.هذه الملاحظة هي قانون دالتون للضغوط الجزئية. بتطبيق قانون الغاز المثالي،و الضغوط الجزئية يتم استبدال مكونات الغاز الفردية بمتغيرات قابلة للقياس. لأن الغازات في الخليط تشغل نفس الحجم وعند نفس درجة الحرارة،يمكن تبسيط المعادلة.مجموع مولات المكونات الفردية يساوي العدد الإجمالي للمولات لجميع مكونات الغاز،n-total. لذلك،الضغط الكلي لخليط الغاز يساوي مجموع n مضروبًا في الثابت R-T على V.عدد مولات المكون مقسومة على إجمالي عدد المولات في الخليط هو الكسر الجزيئي. إعادة ترتيب الكسر المولي لإيجاد إجمالي عدد المولات،واستبدال n-total في قانون دالتون،للضغوط الجزئية،ينتج عنه التعبير عن الضغط الكلي.بإعادة الترتيب مرة أخرى،الضغط الجزئي للغاز في الخليط،هو حاصل ضرب الكسر الجزيئي الخاص به والضغط الكلي للخليط. لذلك،في خليط الغازات،الضغط الجزئي من أي مكون،i،يساوي الكسر المولي من i،مضروبًا في الضغط الكلي. كمثال على الحساب،لنفترض أن إناء مملوء بـ غازان،الهليوم والأرجون،و يشغل الأرجون 40٪من الحجم.هذا يعني أن الكسر الجزيئي للأرجون هو 0.4. إذا كان الضغط الإجمالي 4 ضغط جوي،فما هو الضغط الجزئي للهيليوم؟باستخدام معادلة الضغط الجزئي للغاز،الضغط الجزئي للأرجون يساوي الكسر الجزيئي مضروباًفي الضغط الكلي. وهكذا،فإن 0.4 في 4 ضغط جوي يعطي الضغط الجزئي للأرجون 1.6 ضغط جوي.لأن مجموع الضغوط الجزئية يساوي الضغط الكلي،و المعادلة يمكن إعادة ترتيبها بحيث يمكن للضغط الجزئي للأرجون أن يتم طرحه من الضغط الكلي. وبالتالي،فإن الضغط الجزئي للهيليوم هو 2.4 ضغط جوي.

خليط الغازات- قانون دالتون

ما لم تتفاعل الغازات الفردية كيميائياً مع بعضها البعض، فإن الغازات الفردية الموجودة في خليط من الغازات لا تؤثر على ضغط بعضها البعض. ويمارس كل غاز في الخليط الضغط نفسه الذي سيمارسه إذا كان موجوداً بمفرده في الحاوية. ويُطلق على الضغط الذي يمارسه كل غاز على حدة في خليط بالضغط الجزئي له. وهذا يعني أنه في الخليط الذي يحتوي على ثلاثة غازات مختلفة A وB وC، إذا كان PA هو الضغط الجزئي للغاز A؛ و PB هو الضغط الجزئي للغاز B؛ و PC هو الضغط الجزئي للغاز C؛ فإن الضغط الإجمالي يمكن حسابه بالمعادلة 1:  <img alt="Eq1" src="https://www.jovecore.com/CDNSource/lessons/1038/1038_Equations-01.png" style="height: 40px;" />وهذا هو قانون دالتون’s الذي يشتمل على ضغوط جزئية: ذلك أن الضغط الإجمالي لمزيج من الغازات المثالية يعادل مجموع الضغوط الجزئية لغازات المكونات. افترضnA، nB، و nC هو عدد المولات لكل من الغازات الموجودة في الخليط. إذا أطاع كل غاز معادلة الغاز المثالي، فيمكن كتابة الضغط الجزئي كما يلي: <img alt="Eq2" src="https://www.jovecore.com/CDNSource/lessons/1038/1038_Equations-02.png" style="height: 40px;" />نظراً لأن كل الغازات في درجة الحرارة نفسها وتحتل الحجم نفسه، فإن الاستعاضة في المعادلة 1 تعطينا: <img alt="Eq3" src="https://www.jovecore.com/CDNSource/lessons/1038/1038_Equations-03.png" style="height: 40px;" />تشير المعادلة إلى أنه عند درجة الحرارة الثابتة والحجم الثابت، يتم تحديد إجمالي ضغط عينة الغاز بواسطة العدد الإجمالي لمولات الغاز الموجودة. بالنسبة لخلائط الغازات، من الملائم تقديم كمية تسمى جزء من المول، χ، وهي تكون معرّفة بأنها عدد مولات مادة معينة في خليط مقسومة على إجمالي عدد المولات لجميع المواد الموجودة. بطريقة رياضية، يتم التعبير عن الجزء من المول للمادة A في مزيج مع B وC في صورة <img alt="Eq4" src="https://www.jovecore.com/CDNSource/lessons/1038/1038_Equations-04.png" style="height: 40px;" />وبالمثل، فإن الجزء من المول لـ B وC هو؛ <img alt="Eq5" src="https://www.jovecore.com/CDNSource/lessons/1038/1038_Equations-05.png" style="height: 40px;" /><img alt="Eq6" src="https://www.jovecore.com/CDNSource/lessons/1038/1038_Equations-06.png" style="height: 40px;" />الجمع بين معادلة الجزء من المول للمادة a والمعادلة الخاصة بالضغط الجزئي يعطينا: <img alt="Eq7" src="https://www.jovecore.com/CDNSource/lessons/1038/1038_Equations-07.png" style="height: 40px;" />يرتبط الضغط الجزئي للغاز A بإجمالي ضغط خليط الغاز عن طريق الجزء من المول الخاص به. وبعبارة أخرى، فإن ضغط الغاز في خليط من الغازات هو ناتج الجزء من المول والضغط الإجمالي للخليط. هذا النص مقتبس من <a href="https://openstax.org/books/chemistry-2e/pages/9-3-stoichiometry-of-gaseous-substances-mixtures-and-reactions">Openstax, Chemistry 2e, Section 9.3: Stoichiometry of Gaseous Substances, Mixtures, and Reactions.</a>

ما لم تتفاعل الغازات الفردية كيميائيا مع بعضها البعض ، فإن الغازات الفردية في خليط من الغازات لا تؤثر على ضغط بعضها البعض. كل غاز ...

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JoVE Core

الكيمياء

واحد

Gases

الغازات

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

gas pressure in mixtures: partial pressures

Gas pressure in mixtures is described by partial pressure and mole fraction. When gases do not chemically react, each gas in the mixture acts as if it were alone in the container. The pressure from one gas is called its partial pressure.

For a mixture of three gases, A, B, and C, the total pressure equals the sum of their partial pressures: PA, PB, and PC. This is Dalton's law of partial pressures. It states that the total pressure of a mixture of ideal gases is the sum of the pressures from each gas.

If each gas follows the ideal-gas equation, its partial pressure can be written in terms of moles, temperature, and volume. Because every gas in the mixture has the same temperature and takes up the same volume, these terms can be combined. At constant temperature and constant volume, the total pressure depends on the total number of moles of gas present.

For gas mixtures, chemists also use mole fraction, x. Mole fraction is the number of moles of one substance divided by the total number of moles in the mixture. For gas A in a mixture with B and C, the mole fractions of A, B, and C are found in this way.

Mole fraction also links directly to partial pressure. The partial pressure of gas A equals its mole fraction times the total pressure of the mixture. In other words, a gas's pressure in a mixture is its share of the total pressure.

Gas Pressure in Mixtures: Partial Pressures

gas-pressure-in-mixtures-partial-pressures

definition and measurement of pressure: atmospheric pressure, barometer, and manometer

definition-measurement-pressure-atmospheric-pressure-barometer

Pressure Units and Tools for Gas Measurement

Pressure is the force applied to a given area, and gas pressure comes from gas molecules colliding with surfaces. Each collision is tiny, but many collisions over a small area can create high pressure. Pressure increases when force increases or when the area gets smaller. It decreases when force drops or when the area gets larger. Pressure is measured in pascals, or Pa, in the SI system. One pascal equals 1 newton per square meter, and a newton is a unit of force equal to 1 kg·m/s2. A pascal...

gas laws: boyle's, gay-lussac, charles', avogadro's, and ideal gas law

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How Gas Pressure, Volume, and Temperature Change

Gas pressure, volume, temperature, and amount are linked by several gas laws. Scientists found these relationships by studying how a confined gas changes when one variable is held constant and another changes. These patterns apply to an ideal gas, which is a useful model for gases under low pressure and high temperature. Gay-Lussac’s law, also called Amontons’s law, connects pressure and temperature. If gas is trapped in a rigid container, the volume and number of moles stay constant. When the...

applications of the ideal gas law: molar mass, density, and volume

applications-of-the-ideal-gas-law-molar-mass-density-and-volume

Ideal Gas Law at STP and Gas Density

The ideal gas law links pressure, volume, number of moles, and temperature. It helps explain how gas volume changes when pressure or temperature changes. At standard temperature and pressure, or STP, the values are 273.15 K and 1 atm. At STP, one mole of an ideal gas occupies about 22.4 L. This is called the standard molar volume. The gas can be hydrogen, oxygen, argon, or carbon dioxide, and the volume is still about 22.4 liters. Half a mole occupies 11.2 L, and 2 moles occupy 44.8 L. The...

mixtures of gases: dalton's law of partial pressures and mole fractions

Gas pressure in mixtures is described by partial pressure and mole fraction. When gases do not chemically react, each gas in the mixture acts as if it were alone in the container. The pressure from one gas is called its partial pressure. For a mixture of three gases, A, B, and C, the total pressure equals the sum of their partial pressures: PA, PB, and PC. This is Dalton's law of partial pressures. It states that the total pressure of a mixture of ideal gases is the sum of the pressures from...

chemical stoichiometry and gases: using ideal gas law to determine moles

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Stoichiometry of Gases with the Ideal Gas Law

Chemical stoichiometry links the amounts of reactants and products in a chemical reaction. For gases, those amounts can also be measured by volume. If a gas’s volume, pressure, and temperature are known, the ideal gas equation can be used to find the number of moles present. The same idea works in reverse. If the moles of a gas are known, its volume can be found at any temperature and pressure. The transcript gives an example using 8.88 g of gallium reacting with excess hydrochloric acid.

basic postulates of kinetic molecular theory: particle size, energy, and collision

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Kinetic Molecular Theory and Gas Behavior

Kinetic molecular theory explains gas behavior at the particle level. It gives a microscopic model for what happens when pressure or temperature changes. Gas laws describe how macroscopic properties change, but they do not explain why those changes happen. The theory was put into a complete form by Rudolf Clausius in 1857. It was built from hundreds of experimental observations about gases. Those observations helped explain the different gas laws through a few basic postulates. One key idea...

kinetic molecular theory and gas laws explain properties of gas molecules

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Gas Pressure Patterns in Kinetic Molecular Theory

Kinetic molecular theory explains gas pressure by linking it to the motion of gas molecules. Gas pressure comes from rapidly moving molecules hitting the walls of a container. It depends on how many molecules strike a unit area in a given time. The theory also helps explain the main gas laws. In Gay-Lussac’s law, also called Amontons’s law, raising temperature increases the average speed and kinetic energy of gas molecules. If volume stays constant, the molecules collide with the walls more...

kinetic molecular theory: molecular velocities, temperature, and kinetic energy

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Gas Particle Speed Distributions and Temperature

Gas particle speed distributions and temperature are key ideas in the kinetic molecular theory. This theory explains the gas laws by describing how gas molecules move, collide, and share energy. Gas molecules do not all move at the same speed. A gas sample has an average speed and an average kinetic energy, but individual molecules move at different speeds. Their collisions are elastic, which means momentum is conserved. Because so many molecules collide, the overall speed distribution stays...

behavior of gas molecules: molecular diffusion, mean free path, and effusion

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Gas Particle Motion, Diffusion, and Effusion

Gas particle motion, diffusion, and effusion explain how gases spread and escape in everyday settings. Gas molecules move at very high speeds, but they collide with other gas molecules and change direction many times before reaching a target. At room temperature, a gas molecule can experience billions of collisions each second. The mean free path is the average distance a molecule travels between collisions. This distance becomes larger when pressure decreases. In general, the mean free path...

real gases: effects of intermolecular forces and molecular volume deriving van der waals equation

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Real Gases: When the Ideal Gas Law Breaks Down

Real gases are gases that do not always follow the ideal gas law, PV = nRT, especially when pressure is high or temperature is low. The ideal gas model assumes gas particles have no attractive or repulsive forces and take up negligible space compared with the container. At room temperature and 1 atm or less, many gases behave close to ideally. When conditions change, the measured relationships between pressure, volume, and temperature can drift away from the ideal prediction. One way to see...

key terms and concepts

Learn how partial pressure and mole fraction describe gas mixtures, and how Dalton's law connects each gas to the total pressure.

Gas Pressure in Mixtures: Partial Pressures | JoVE K12

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Ohio’s Learning Standards and Model Curriculum

Interactions Of Matter

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CHEM.10

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New York State Science Learning Standards

Physical Science

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Classifying Matter by State

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Matter: Pure Substances and Mixtures
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Physical and Chemical Properties of Matter

The characteristics that enable us to distinguish one substance from another are called properties.

Physical Properties of Matter

A physical property is ...

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Molecular Comparison of Gases, Liquids, and Solids

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Intermolecular vs Intramolecular Forces

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Intermolecular Forces

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Comparing Intermolecular Forces: Melting Point, Boiling Point, and Miscibility

Intermolecular forces are attractive forces that exist between molecules. They dictate several bulk properties, such as melting points, boiling points, ...

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Surface Tension, Capillary Action, and Viscosity

Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded ...

States of Matter and Phase Changes

The internal energy of a substance&#8212;the total kinetic energy of all its molecules and the potential energy of their associated forces&#8212;depends ...

Phase Transitions

Whether solid, liquid, or gas, a substance&#39;s state depends on the order and arrangement of its particles (atoms, molecules, or ions). Particles in the ...

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Phase Transitions: Vaporization and Condensation

The physical form of a substance changes on changing its temperature. For example, raising the temperature of a liquid causes the liquid to vaporize ...

Vapor Pressure

When a liquid vaporizes in a closed container, gas molecules cannot escape. As these gas phase molecules move randomly about, they will occasionally ...

Clausius-Clapeyron Equation

The equilibrium between a liquid and its vapor depends on the temperature of the system; a rise in temperature causes a corresponding rise in the vapor ...

Phase Transitions: Melting and Freezing

Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy ...

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Phase Transitions: Sublimation and Deposition

Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and ...

Heating and Cooling Curves

When a substance&#8212;isolated from its environment&#8212;is subjected to heat changes, corresponding changes in temperature and phase of the substance ...

Phase Diagrams

A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. ...

Use models to explain how changes in energy affect the arrangement and movement of the particles in solids, liquids, and gases, as well as the relative strengths of their intermolecular forces.

PS.Chm.7.1

Energy Basics

Chemical reactions, such as those that occur when you light a match, involve changes in energy as well as matter.

Chemical changes and their accompanying ...

First Law of Thermodynamics

Energy Conservation

Energy can be converted from one form into another, but all of the energy present before a change occurs always exists in some form ...

Internal Energy

The total of all possible kinds of energy present in a substance is called the internal energy (U), sometimes symbolized as E. Suppose a system with ...

Quantifying Heat

Thermal Energy&#160;

Microscopically, thermal energy is the kinetic energy associated with the random motion of atoms and molecules. Temperature is a ...

Quantifying Work

As a system undergoes a change, its internal energy can change, and energy can be transferred from the system to the surroundings, or from the ...

Enthalpy

Chemists ordinarily use a property known as enthalpy (H) to describe the thermodynamics of chemical and physical processes. Enthalpy is defined as the sum ...

Thermochemical Equations

For a chemical reaction (the system) carried out at constant pressure &ndash; with the only work done caused by expansion or contraction &ndash; the ...

Constant Pressure Calorimetry

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Constant Volume Calorimetry

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Using Differential Scanning Calorimetry to Measure Changes in Enthalpy

Source: Laboratory of Dr. Terry Tritt &#8212; Clemson University
Differential Scanning Calorimetry (DSC) is a method of thermodynamic analysis based on ...

Hess's Law

There are two ways to determine the amount of heat involved in a chemical change: measure it experimentally, or calculate it from other experimentally ...

Standard Enthalpy of Formation

Enthalpy changes are typically tabulated for reactions in which both the reactants and products are at the same conditions. A standard state is a commonly ...

Enthalpies of Reaction

Hess&rsquo;s law can be used to determine the enthalpy change of any reaction if the corresponding enthalpies of formation of the reactants and products ...

Use mathematics and computational thinking to execute simple calorimetric calculations based on the Law of Conservation of Energy.

PS.Chm.7.2

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Unless individual gases chemically react with each other, the individual gases in a mixture of gases do not affect each other&rsquo;s pressure. Each gas ...

Chemical Stoichiometry and Gases: Using Ideal Gas Law to Determine Moles

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In addition to measuring quantities ...

Basic Postulates of Kinetic Molecular Theory: Particle Size, Energy, and Collision

The ideal-gas equation, which is empirical, describes the behavior of gases by establishing relationships between their macroscopic properties. For ...

Kinetic Molecular Theory and Gas Laws Explain Properties of Gas Molecules

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Kinetic Molecular Theory: Molecular Velocities, Temperature, and Kinetic Energy

The kinetic molecular theory qualitatively explains the behaviors described by the various gas laws. The postulates of this theory may be applied in a ...

Behavior of Gas Molecules: Molecular Diffusion, Mean Free Path, and Effusion

Although gaseous molecules travel at tremendous speeds (hundreds of meters per second), they collide with other gaseous molecules and travel in many ...

Real Gases: Effects of Intermolecular Forces and Molecular Volume Deriving Van der Waals Equation

Thus far, the ideal gas law, PV = nRT, has been applied to a variety of different types of problems, ranging from reaction stoichiometry and empirical and ...

Ideal Gas Law

Source: Laboratory of Dr. Andreas Z&#252;ttel - Swiss Federal Laboratories for Materials Science and Technology
The ideal gas law describes the behavior ...

Derivation of the Ideal Gas Law
Gases are a fundamental state of matter. A gas is a collection of molecules that have a significant distance between their ...

Source: Smaa Koraym at Johns Hopkins University, MD, USA

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	Determining the Mass of the Unknown LiquidExpand
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Use mathematics and computational thinking to explain the relationships among pressure, temperature, volume, and quantity of gas, both qualitatively and quantitatively.

Understand the relationship among pressure, temperature, volume, and phase.

Gas Pressure in Mixtures: Partial Pressures

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