Boyle's Law PDF

**BOYLE'S LAW** **Pressure-Volume Relationship of Gases** **Macroscopic Properties of Gases** **Pressure** - is the force applied per unit area by the gas molecules as they hit the walls of the container. **Volume** - is the space occupied by the gas molecules. The volume of a gas...

**BOYLE'S LAW** **Pressure-Volume Relationship of Gases** **Macroscopic Properties of Gases** **Pressure** - is the force applied per unit area by the gas molecules as they hit the walls of the container. **Volume** - is the space occupied by the gas molecules. The volume of a gas depends on the container. **Boyle's Law** Shows pressure-volume relationship at constant temperature and moles of gas: For a given initial and final pressure and volume, the relationship is given by  **P-V diagrams** - Represent the changes in pressure of a gas with respect to its volume provided that temperature and amount of gas remain constant EXAMPLE: A tank of argon gas has a pressure of 5.00 atm and a volume of 10.00 L. What would be its pressure (in atm) if it was transferred to another tank with a volume of 20.00 L? A tank of oxygen gas has a pressure of 621 torr and a volume of 0.324 L. What would be its pressure (in torr) if it was transferred to another tank with a volume of 2.00 L?  A gas with an unknown composition was contained in a 500mL container and gave a pressure of 0.75 bar. What will be its final pressure (in bar) if it was moved to a 2.00 L tank?  A nitrogen gas contained in a 5000.00 mL chamber has a pressure of 1000 torr. Calculate the final pressure (in torr) when it is moved to a 20.00 L tank. A gas with an unknown composition was contained in a 500mL container and gave a pressure of 0.75 bar. What will be its final pressure in atm if it was moved to a 2.00 L tank?  Boyle's law states that the pressure of a gas at constant temperature is inversely proportional to its volume. It can also be stated in one of two ways: - As the pressure of a gas increases at constant temperature, its volume decreases. - As the pressure of a gas decreases at a constant temperature, its pressure increases.  **CHEMICAL REACTIONS** **Chemical Reactions** - processes by which chemicals interact with one another to form a new compound (when chemical bonds between atoms are formed and broken) - processes where reactants, the starting materials, are transformed into new materials or substances referred to as products **Change in Color** **Change in Temperature** - heat is released or absorbed when atoms are being broken or formed in a chemical reaction example: combustion (The combustion of wood releases high amounts of heat.) **Formation of Gas** - **effervescence** - evolution of a gas - mixing acetic acid in vinegar and baking soda, creates effervescence the form of carbon dioxide, the gas that readily escapes the mixture.  - Yeast is added to break down the sugars in the flour. As a result, the dough rises because of the formation of carbon dioxide gas. - The rising of dough is caused by the production of CO2 gas. **Formation of Precipitate** **Precipitation** - results when two aqueous solutions upon mixing form an insoluble solid known as a precipitate - Mixing of silver nitrate solution and sodium chloride solution in a test tube forms AgCl. **REMEMBER!** In a chemical reaction, there are different indicators that can be observed: 1. color change; 2. temperature change; 3. formation of gas; and 4. formation of precipitates. **FORMATION OF CHEMICAL BONDS** **Chemical Bonding** - Almost all the elements on the periodic table are found in combination with other atoms in nature. Exception: noble gases - When atoms combine, compounds are formed. **Compound** - composed of two or more elements that are combined in definite proportions - possesses certain physical and chemical properties that make them unique. - a force of attraction that holds atoms of different elements in a compound - relates to other concepts such as molecule formation and chemical reactions - explains how substances are formed and why they behave in a certain way - to fully grasp the concept of bonding → **atomic structure** - subatomic particles: - protons (positively-charged) - subatomic particles: - neutrons (neutral) - nucleus → where protons and neutrons are found - subatomic particles: - electrons (negatively-charged) - electrons surround the nucleus and are located at various energy levels - Protons and electrons having opposite charges attract one another through a simple electromagnetic force. - The negatively charged electrons that are moving around the nucleus are attracted to the positively charged protons in it. - Electrons that are positioned between two nuclei are attracted to both of them. - This attraction holds two particles together, eventually forming a chemical bond.  Properties of an atom rely on the strength of attractions and repulsions among the nucleus and electrons The nature of the **electron cloud** - the area where electrons move around its nucleus - what makes atoms distinguishable from one another - The distinct electron cloud of each element - chemical properties - extent of reactivity - Only valence electrons or electrons found in the outermost shell of an element are involved in the chemical bonding. - Atoms form chemical bonds to gain stability. - An atom is at its most stable state when its outermost shell is either empty of electrons or is filled with a certain number of electrons. - Atoms tend to **transfer** or **share electrons.** - The strength of a chemical bond is associated with the sharing or transferring of electrons. **TYPES OF CHEMICAL BONDING** Categorized based on how metals and nonmetals combine - ionic bonding - covalent bonding - metallic bonding  **IONIC BONDING** - the chemical bond that exists between a metal and a nonmetal - **electron transfer** - occurs when the valence electrons of a metallic element are transferred to the atom of nonmetals - often observed between atoms with large differences in their tendencies to lose or gain electrons. When electrons transfer from metal to nonmetal, each atom forms an ion (charged particle) with a noble gas electron configuration. **Types of Ions** 1. cations (positively charged ions) 2. anions (negatively charged ions) - Na atom transfers an electron to Cl atoms - Since Na atom lost an electron it becomes a **cation**. - On the other hand, Cl atom accepted an electron which turned it into an **anion**. - These oppositely charged atoms attract one another in an **ionic compound.** - exists between nonmetals - electron sharing - occurs when there is a little difference in the tendencies of atoms to gain or lose electrons. - nonmetals: high ionization energy and highly negative electron affinity Example: methane (CH4) - C atom = 8 e-s in its outer shell (maximum number of valence e-s that C atom can hold) - H atom = two valence e-s (maximum number of valence e-s that H can hold) - The valence electrons of these elements are attracted to each atom\'s nucleus. - The shared electron pairs are typically localized between the two atoms, linking them in a covalent bond of a particular length and strength. **REMEMBER!** **METALLIC BONDING** - exists between metallic elements - metallic atoms pool their valence electrons into a "sea" of electrons that "flows" between and around each metal-ion core - a strong, attractive force between atoms of a metallic element - **metals:** relatively large atoms with few outer electrons that are well shielded by their core electrons. - low ionization energy - slightly positive or negative electron affinity - metal atoms share electrons but not in the same manner as how electrons are shared in covalent bonds. - Exhibit the delocalization of electrons - These negatively-charged particles move freely throughout the metal - Many physical and chemical properties of metals are attributed to its delocalized valence electrons **REMEMBER!** Metallic bonding can be regarded as electron sharing between metallic atoms. Unlike the localized electrons in covalent bonds, metallic bonds exhibit the delocalization of electrons. **MACROSCOPIC PROPERTIES OF GASES** **Temperature** - measure of the average kinetic energy of gas particles - higher temperature = higher average kinetic energy of gas particles **Volume** - measure of the space occupied by the gas particles - For gases, this depends on the volume of the container. **Pressure** - defined as force applied per unit area - SI unit is Pascals (Pa) - For gases, this refers to the force applied by the gas molecules per unit area of the container wall. - Other units: atm, bar, Torr, mmHg  **Pressure** - measured using manometers and barometers. - A simple barometer setup is shown in the figure here. **REMEMBER!**  Convert 1.33 atm to bar.  **THE ATOMIC THEORY** **The Concept of Atomos** **Democritus (470-380 BC )** - The beginning of the ancient concept of an atom started when Democritus stated that all matter consists of tiny particles that were so tiny that they could not be further broken down into any smaller pieces. - He called these tiny particles as atomos which literally means indivisible. - This concept is also known as atomism, overall it describes an **atom as both indivisible and an indestructible particle.** **The Primal Matter: What Is the Basic Element?** - **Thales** (640-540 BC) thought it was water. - **Anaximenes** (611-546 BC) thought it was air. - **Heraclitus** (540-475 BC) thought it was fire. - **Empedocles** (430-540 BC) though it was Earth (land). **Dalton's Elements**  - In 1803, John Dalton, developed the first atomic theory and introduced the use of symbols to represent the elements. - These elements can combine to form compounds. **Dalton's Compounds**  **Dalton's Atomic Theory** The postulates about the nature of matter on which Dalton's atomic tsheory is based are summarized as follows: **Postulate 1** - Elements are composed of extremely small particles, called atoms. **Postulate 2** - All atoms of a given element are identical, having the same size, mass, and chemical properties. The atoms of one element are different from the atoms of all other elements. **Postulate 3** - Compounds are composed of atoms of more than one element. In any compound, the ratio of the numbers of atoms of any two of the element present is either an integer or a simple fraction.  **Postulate 4** - A chemical reaction involves only the separation, combination, or rearrangement of atoms; it does not result in their creation or destruction. **Dalton's Atomic Model** - Dalton's atomic model is represented as solid, hard spheres, like billiard (pool) ball as he thought that atoms were the smallest particles of matter. - Dalton's billiard model of an atom **Dalton's Atomic Theory** **Postulates 1 and 2** explain that, an element, regardless of size and source, have the same properties. No two elements have the same set of properties although they may be similar in some aspects. For example, as a hypothetical representation of a unique atom as shown below, element X is different from element Y, so as element Z. **Atoms Combine in a Certain Ratio** **Postulate 3** only explains that when atoms combine, the ratio of the atoms involved must be a whole number, the ratio also plays a key role in the nature of the compound formed.  **Atoms Are Indestructible** - According to the **fourth postulate** of Dalton, when atoms are combined, they are only separated, combined, or rearranged to form a new compound. The identity of the atoms involved are neither altered nor changed. **TYPES OF CHEMICAL REACTIONS** - Types can be generalized into five categories. - For a chemical reaction, a new substance must be formed. **Synthesis Reactions** - **Combination reactions** - Reactions where two or more simple substances (generally elements) combine to form new compounds **Decomposition Reactions** - A compound is broken down into simpler compounds or even its starting elements - Can be regarded as the opposite of synthesis reactions  - Decomposition of a compound is possible through the application of either heat, energy, a catalyst, or a combination of these. - In this reaction, when electricity is passed through water, it decomposes to its elemental composition, hydrogen gas and oxygen gas. - Compounds can also form after a decomposition reaction. For example, the decomposition of metal carbonate into a metal oxide and carbon dioxide gas.  **Single Displacement Reactions** - One element replaces a similar element in the compound C replaces B from the compound AB to make a compound AC and an elemental B (a type of redox reaction) **An example is a Daniell cell**  Zinc can substitute for copper in a solution of copper sulfate **Activity Series** - Predicts whether single displacement reactions proceed or not **Single Displacement Reactions** - Many metals react with acids, and when they react, they form hydrogen as one of the products.  **Double Displacement Reactions** - occurs when two ionic substances react and exchange ions with one another where A and C are cations (positively charged ions), and B and D are anions (negatively charged ions) **Double Displacement Reactions** Typically happens in an aqueous medium Two types of double displacement reactions 1. acid-base reactions 2. precipitation reactions **Acid-base reactions or neutralization reactions** Combinations of an acid and a base forming a salt and water  **Precipitation Reactions** - Happen when the cation of one compound combines with the anions of another compound, forming an insoluble solid known as a **precipitate** **REMEMBER!** There are two types of double displacement reactions---neutralization reaction and precipitate formation. In a double displacement reaction, one of the products is usually a solid precipitate, a gas, or a molecular compound such as water. **Combustion Reactions** - Substance reacts with oxygen gas, releasing a large amount of energy in the form of light and heat Example: combustion of organic compounds (e.g. hydrocarbons) results in the formation of carbon dioxide and water The combustion of methane, for example:  There are five main categories of chemical reactions: - synthesis reaction; - decomposition reaction; - single displacement reaction; - double displacement reaction; and - combustion reaction