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37826294-3bce-4e63-98ad-5e0f89c2dfca Conservation of Mass Summary In chemical reactions, the total mass of the reactants is equal to the total mass of the products. This principle states that matter cannot be created or destroyed.

9f61eea9-b517-46ae-a62d-2d02c62243b5 Know that in for endothermic reactions H products > H reactants, ∆ H> 0 and reaction absorbs energy Summary In chemical reactions, an endothermic reaction is one that absorbs energy from the surroundings. It is characterized by the fact that the enthalpy (H) of the products is greater than the enthalpy of the reactants. This change in enthalpy (∆H) is positive, indicating that energy is absorbed during the reaction. To understand endothermic reactions, let's consider an everyday example: the process of cooking pasta. When you boil water and add pasta to it, the reaction between the pasta and the hot water is endothermic. The energy from the heat source is absorbed by the pasta, causing it to cook and increase in temperature. In an endothermic reaction, the potential energy of the products is higher than that of the reactants. This means that the reactants have a lower energy level compared to the products. As the reaction progresses, energy is absorbed from the surroundings, leading to an increase in potential energy. On a potential energy diagram for an endothermic reaction, the reactants are represented at a lower energy level compared to the products. The curve starts at a lower point (representing the energy of the reactants) and gradually increases (representing the increase in potential energy) as the reaction proceeds towards the products. The difference in potential energy between the reactants and products is the amount of energy absorbed from the surroundings. The positive value of ∆H indicates that the reaction absorbs energy. This energy can be in the form of heat, light, or any other form of energy. In the case of the cooking pasta example, the absorbed energy is in the form of heat from the boiling water. Endothermic reactions are essential in various processes. For instance, in photosynthesis, plants absorb energy from sunlight to convert carbon dioxide and water into glucose and oxygen. This process requires energy input to drive the reaction. Another example is the process of evaporation. When a liquid evaporates, it absorbs energy from the surroundings, causing a cooling effect. This is because the liquid particles need to gain energy to break the intermolecular forces and transform into a gas state. Endothermic reactions are also prevalent in chemical reactions used for cooling, such as instant cold packs or ice packs. These packs contain chemicals that undergo an endothermic reaction when activated, absorbing heat from the surroundings and providing a cooling sensation. In summary, endothermic reactions are characterized by the absorption of energy from the surroundings. The enthalpy of the products is greater than that of the reactants, resulting in a positive change in enthalpy (∆H). On a potential energy diagram, the potential energy increases from the reactants to the products, indicating the energy absorbed during the reaction. Understanding endothermic reactions helps us comprehend processes that require energy input and have a cooling effect, such as cooking, photosynthesis, evaporation, and cooling packs.

fde85c58-101d-46eb-9a7c-0451dd29502c understand that chemical reactions are accompanied by enthalpy changes and these changes can be exothermic (ΔH is negative) or endothermic (ΔH is positive) Summary Chemical reactions are accompanied by enthalpy changes, which refer to the heat energy exchanged during the reaction. Enthalpy (H) represents the total energy content of a system, including both internal energy and the energy associated with pressure and volume. By studying enthalpy changes, we gain insights into the energy flow and transformations occurring in chemical reactions. Enthalpy changes can be classified as exothermic or endothermic based on the sign of ΔH, which represents the change in enthalpy. In exothermic reactions, the products have lower enthalpy than the reactants, resulting in a negative ΔH value. This negative ΔH indicates that the reaction releases heat energy to the surroundings. For example, when wood burns, it undergoes an exothermic reaction. The reactants (wood and oxygen) have a higher enthalpy than the products (carbon dioxide, water, and heat), leading to a negative ΔH. The heat released during this reaction warms up the surroundings, making it feel warm and giving off light. On the other hand, endothermic reactions have products with higher enthalpy than the reactants, resulting in a positive ΔH value. This positive ΔH indicates that the reaction absorbs heat energy from the surroundings to proceed. An example of an endothermic reaction is the process of photosynthesis in plants. During photosynthesis, plants convert carbon dioxide and water into glucose and oxygen using energy from sunlight. This reaction requires energy input, which is absorbed from the surroundings, resulting in a positive ΔH. Understanding whether a reaction is exothermic or endothermic is crucial for various applications. It helps us predict the energy changes associated with reactions and understand their impact on the surroundings. Exothermic reactions often have practical applications such as combustion for energy generation, while endothermic reactions are commonly utilized in processes like thermal decomposition or cooling systems. In summary, enthalpy changes in chemical reactions can be exothermic (ΔH is negative) or endothermic (ΔH is positive). Exothermic reactions release heat energy to the surroundings, while endothermic reactions absorb heat energy from the surroundings. By recognizing and understanding these enthalpy changes, we gain insights into the energy dynamics of chemical reactions and their significance in various real-world processes.

6de5efa8-0086-4f23-9235-a10af8abad04 Melting/Fusion Summary The change of a substance from a solid to a liquid state at a specific temperature.

4a86fc54-4e19-4320-82f5-aec48e238da7 Heating Curve Summary A graphical representation of the relationship between temperature and time as a substance is heated.

99b6bec9-583e-4c2a-b3b9-b602a1fb52c9 Balancing Chemical Equations Summary -

249e4b5d-153c-4db5-b7ef-4e42d4ea12fe Types of Chemical Reactions and Solution Stoichiometry Balancing Redox Reactions Summary

c89eee7b-ead0-40a3-aa04-17f258e326d7 Writing Equations Summary Including the energy required or released

5a382f68-41fb-4947-8b4e-e83ad9699709 Transition metals: they fall between groups 2 and 3. They form more than one charged ion (iron forms iron (II), Fe2+, and iron (III), Fe3+, ions). They form colored compounds (copper compounds are blue or green, iron (II) compounds are pale green while iron (III) compounds are brown). Summary

56daf7db-50c2-4b6a-9429-151f75319d8d The boiling and melting points of alkali metals decreases as their atomic # increases. Summary

0680d4fb-a194-4c18-b4f1-2e7387586c8d Exothermic Reaction Summary Is a reaction which releases heat to the surrounding. As heat is released, the temperature of the surrounding increases. Cooling a substance, freezing, condensation are examples of exothermic processes

e813ddb8-83c8-4092-a77b-068374b615c1 Mass of a Nucleus Summary The mass of a nucleus refers to the total mass of protons and neutrons present within the nucleus of an atom. It is a fundamental property that determines the overall mass of an atom. To understand the mass of a nucleus, let's consider an everyday example: a fruit bowl. Imagine each fruit in the bowl represents a proton or a neutron. The combined mass of all the fruits in the bowl would be analogous to the mass of the nucleus, which is composed of protons and neutrons. The mass of a nucleus is measured in atomic mass units (amu), with 1 amu being approximately equal to the mass of a proton or a neutron. The number of protons, known as the atomic number, determines the element, while the sum of protons and neutrons gives the mass number of an atom. For instance, let's take the element carbon. A carbon nucleus contains 6 protons and usually 6 neutrons, resulting in a total mass of approximately 12 atomic mass units. In a similar manner, let's consider a bag of marbles. Each marble can represent a proton or a neutron. The total weight of all the marbles in the bag would correspond to the mass of the nucleus, which is determined by the combined mass of protons and neutrons. The mass of a nucleus is crucial in understanding the stability and behavior of atoms. Isotopes, which are atoms of the same element with different numbers of neutrons, have different masses due to the varying number of neutrons in their nuclei. Mass defects are also observed in nuclei. The mass of a nucleus is slightly less than the combined mass of its individual protons and neutrons. This difference in mass is known as the mass defect and is a consequence of Einstein's famous equation, E=mc². To illustrate, think of a jar filled with marbles representing protons and neutrons. If you were to calculate the combined mass of all the marbles, it would be slightly greater than the actual mass of the filled jar due to the mass defect. The mass defect occurs because some of the mass of the nucleus is converted into binding energy, which holds the nucleus together. This binding energy is released during nuclear reactions, such as fusion or fission, where the total mass of the products differs from the mass of the original nucleus. An everyday example of mass defect and binding energy can be observed in the energy released from a nuclear power plant. The difference in mass between the reactant nuclei (such as uranium) and the product nuclei (after fission) is converted into a large amount of energy. In summary, the mass of a nucleus refers to the combined mass of protons and neutrons within an atom's nucleus. It is a fundamental property that influences the stability and behavior of atoms. Examples like a fruit bowl or a bag of marbles help illustrate the concept of the mass of a nucleus, as well as mass defects and binding energy associated with nuclear reactions. Understanding the mass of a nucleus is essential for comprehending atomic structure, isotopes, and the energy transformations that occur in nuclear processes.