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Stoichiometric Calculations with Limiting Reagent Grade 10 SABIS SABIS Solve stoichiometric calculation questions involving a limiting reagent

Hess’s Law Definition Grade 10 SABIS ​ Hess's Law states that the total energy change in a chemical reaction is independent of the pathway taken. In simpler terms, the total energy difference between the reactants and products remains the same, regardless of the intermediate steps involved. I t's like walking from point A to point B using different routes but ending up at the same destination. To illustrate this concept, imagine you want to climb a hill. You can take a direct path or go around the hill through a longer route. Regardless of the path you choose, the total energy change of reaching the top remains the same. Similarly, let's consider the process of cooking a pizza. You can either directly bake it in the oven or prepare the dough and toppings separately before assembling and baking. The total energy change, which is the difference between the raw ingredients and the cooked pizza, remains constant. Hess's Law is based on the principle of energy conservation. It's similar to the idea that you can't create or destroy energy; you can only convert or transfer it. This law applies to all chemical reactions, allowing us to understand and calculate energy changes in a more straightforward manner. An everyday example of Hess's Law can be observed when you prepare a cup of tea. If you add sugar to hot water or separately dissolve sugar in cold water and then heat it, the total energy change due to the sugar dissolving remains the same. Another example is the construction of a Lego house. You can either build it directly from scratch or create separate sections and then assemble them. Regardless of the approach, the total energy change in constructing the complete Lego house remains constant. Hess's Law is particularly useful in cases where it's challenging to measure the energy change directly. By combining multiple reactions with known energy changes, we can calculate the energy change of the desired reaction. To further illustrate Hess's Law, let's consider the process of charging a rechargeable battery. Whether you charge it all at once or in multiple smaller sessions, the total energy change required to fully charge the battery remains the same. Similarly, think about a journey from home to a park. You might take a direct route or make detours along the way, but the total energy change of the journey, such as the fuel consumption in a car, is the same regardless of the route taken. Hess's Law allows scientists to predict and analyze energy changes in complex reactions. It simplifies calculations and provides a fundamental understanding of energy conservation in chemical systems. For instance, if we want to determine the energy change of a reaction that's difficult to measure directly, we can design a series of reactions with known energy changes. By applying Hess's Law, we can add or subtract these reactions to obtain the desired energy change. In summary, Hess's Law states that the total energy change in a chemical reaction remains constant, regardless of the specific pathway taken. This principle is similar to reaching a destination via different routes. It simplifies calculations and allows us to understand and predict energy changes in chemical reactions. Everyday examples, such as preparing tea, building Lego structures, or charging a battery, help illustrate this law in practical terms.

Plateau ​ ​ The flat horizontal section on a heating or cooling curve that represents a phase change occurring at a constant temperature.

Filtrate ​ ​ The liquid that passes through the filter paper during the filtration process.

< Back Atomic Structure Lesson 4 ⚛️ Lesson 4 ⚛️ Explore the world of atomic and ionic radii in this visually enhanced quiz. Discover the patterns of atomic size across the Periodic Table and the changes in ionic radius when atoms gain or lose electrons. Unveil the secrets of the microcosm, one atom at a time! Previous Next ⚛️ 1.1.4 Atomic & Ionic Radius ⚛️ 💥🔬 Navigating the Universe of Atoms: Atomic & Ionic Radii 🔬💥 🌌 Measuring Atomic Size: Atomic Radius 🌌 When we think of the atomic radius, we're actually measuring the size of an atom. 📏 But how? Imagine taking two atoms of the same type, say two hydrogen atoms, bonding them together, and then measuring the distance between their nuclei. 📍📍 The atomic radius is half of this distance. 🧪 But atoms are not all the same size! Just like cities across a country, they show trends across the Periodic Table. 🗺️💡 📉 As you travel across each Period (left to right), atomic radii generally decrease. Why? Well, as you move across, the atomic number increases—meaning more protons. More protons = stronger pull on electrons = smaller atoms. 🔄 📈 On the other hand, as you journey down each Group (top to bottom), atomic radii generally increase. Here, we have more electron shells, which "shield" outermost electrons from the pull of the nucleus—leading to bigger atoms! 🔄 And what about that big jump in size between a noble gas at the end of a period and the alkali metal at the beginning of the next? It's all about the extra shell! More shells = more shielding = larger atomic radius! 💥 🌠 Examining Ion Sizes: Ionic Radius 🌠 The ionic radius, on the other hand, measures the size of an ion—a charged atom. Just like atomic radius, ionic radius also follows certain patterns! 🧩🔍 🔽 If an atom gains extra electrons to become a negatively charged ion (anion), its ionic radius increases. Why? The extra electrons are further from the nucleus and are loosely held, which increases the size. 🔄 🔼 If an atom loses electrons to become a positively charged ion (cation), its ionic radius decreases. Here, the remaining electrons are pulled in tighter by the nucleus, resulting in a smaller ion. 🔄 So, atomic and ionic radii offer a sort of "map" to the universe of atoms and ions. By understanding these trends, you're not just studying chemistry—you're discovering the unseen landscape of the microcosm, one atom (or ion) at a time! 💥🌌

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neutralization reaction Grade 10 SABIS SABIS Exothermic Reaction

Burning magnesium ribbon in air Grade 10 SABIS SABIS Chemical

understand that chemical reactions are accompanied by enthalpy changes and these changes can be exothermic (ΔH is negative) or endothermic (ΔH is positive) A Level Chemistry CIE 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.

< Back Atoms, molecules and stoichiometry This is placeholder text. To change this content, double-click on the element and click Change Content. Chapter Summary Previous Next Learning Outcomes 🎯: Define and use terms such as relative atomic mass, isotopic mass, empirical formula, molecular formula, and the mole in terms of the Avogadro constant. Analyze and use mass spectra to calculate the relative atomic mass of an element. Calculate empirical and molecular formulas using combustion data or composition by mass. Write and construct balanced equations. Perform calculations involving the mole concept, reacting masses, volumes of gases, and volumes and concentrations of solutions. Deduce stoichiometric relationships from calculations involving reacting masses, volumes of gases, and volumes and concentrations of solutions. Relative Atomic Mass and the Mole 🧮: Relative atomic mass is the weighted average mass of naturally occurring atoms of an element on a scale where an atom of carbon-12 has a mass of exactly 12 units. The mole is a unit used to count the number of particles in a substance and is based on the Avogadro constant. Empirical and Molecular Formulas 📝: Empirical formulas show the simplest whole-number ratio of atoms in a compound. Molecular formulas show the total number of atoms of each element present in one molecule or one formula unit of the compound. Balancing Chemical Equations ⚖️: Chemical equations must be balanced to ensure that the number of atoms of each element on the reactants side is equal to the number on the products side.

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