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Melting/Fusion ​ ​ The change of a substance from a solid to a liquid state at a specific temperature.

Air Composition Grade 10 SABIS SABIS

RTP (Room Temperature and Pressure) Grade 10 SABIS SABIS A set of conditions close to room temperature (25°C) and atmospheric pressure used for experimental measurements.

< Back Hydrogen gas​ Part 1 Physical properties of hydrogen 1. Colorless odorless gas 2. Neutral to litmus 3. Less dense than air (so collected by upward delivery) 4. Insoluble in water (can be collected over water) 5. Highly flammable Reaction of Hydrogen Gas with Air Reacts with air violently (oxygen) when in contact with a flame. So it makes a squeaky pop with a lit splint 2H2(g) + O2 --> 2H2O Isotopes of Hydrogen Isotopes are atoms of the same element which have the same number of protons (atomic number) but different number of neutrons (mass number). Preparation of Hydrogen gas First : in Laboratory ​ 1-Preparing hydrogen from water or steam​ Addition of Very reactive metals (example potassium , Sodium , Lithium , Calcium) + liquid water gives hydrogen gas and metal hydroxide. or Addition of metals to steam to produce metal oxide and hydrogen gas 2- Preparing Hydrogen from acids​ Addition of moderately reactive metals like magnesium aluminum zinc or iron to dilute hydrochloric acid or sulfuric acid Note that less reactive metals can not be used to prepare the hydrogen with dilute acids generally metals which are less reactive than hydrogen can not be used Second : Industrially​ 1-Using hydrocarbons​ example by heating a hydrocarbon like methane with steam using a catalyst like nickel , the product is Carbon monoxide and hydrogen gas The carbon monoxide produced can be reheated with more steam using an iron oxide catalyst to produce Carbon dioxide and hydrogen gas 2-Using coke​ Coke is a fuel made of coal The coke is reacted with steam at high temperature (around 1000) degrees celsius to produce carbon monoxide gas and hydrogen gas 3-Using Electrolysis​ Electrolysis is the breakdown of a substance using electric current the water is broken down by electrolysis into hydrogen and oxygen Or the NaCl solution (brine) is broken down into chlorine and Hydrogen gases Previous Next

Heat Content (H) Grade 10 SABIS ​ The amount of potential energy stored in 1 mole of any substance. Heat content, also known as enthalpy, is a concept in thermochemistry that relates to the total energy contained within a substance. Think of heat content as the energy stored in your phone's battery. When the battery is fully charged, it contains a certain amount of energy, similar to the heat content of a substance. Imagine you have a cup of hot coffee. The heat content of the coffee represents the total energy stored in the liquid, which determines how hot it is. If you let the coffee sit for a while, it gradually cools down as it loses heat content to the surroundings. Now, consider a chemical reaction like burning a piece of paper. The heat content of the reactants (paper and oxygen) is different from the heat content of the products (ashes and carbon dioxide). The difference in heat content indicates how much energy is released or absorbed during the reaction . In everyday life, you can observe heat content changes when you cook food. As you apply heat to raw ingredients, their heat content increases, causing them to undergo chemical and physical changes. When you bake a cake, the heat content of the batter transforms it into a delicious dessert. Similarly, when you feel cold after getting out of a swimming pool, it's because the water on your body has a higher heat content than the surrounding air. As heat transfers from your body to the air, you feel a chill. The concept of heat content is essential in designing energy-efficient systems. For example, engineers consider the heat content of fuels when developing engines or power plants to maximize energy conversion. In summary, heat content is like the stored energy within a substance or system. It affects everyday situations like cooking, feeling cold after swimming, and energy conversions in engines. Understanding heat content helps us comprehend the energy changes that occur during chemical reactions and other processes in our daily lives.

Identify diagram of atoms and ions from a given list. Grade 10 SABIS ​

Inert elements: are helium, neon, argon, krypton and xenon. Grade 10 SABIS ​

6 understand that some bond energies are exact and some bond energies are averages A Level Chemistry CIE When discussing bond energies, it is important to recognize that not all bond energies are exact values. Some bond energies are known precisely, while others are represented as average values. Understanding the distinction between exact and average bond energies is essential for accurate calculations and interpretations in chemical reactions. Exact bond energies refer to situations where the energy required to break a specific bond in a particular molecule is precisely known. These values are obtained from experimental measurements or highly accurate theoretical calculations. Exact bond energies are typically available for simple diatomic molecules or stable compounds with well-defined structures. For example, the bond energy of the O-H bond in a water molecule (H2O) is an exact value because it can be directly determined experimentally. The energy required to break this specific bond in water is known with high precision. On the other hand, average bond energies represent the average energy required to break a particular type of bond in a variety of compounds. These values are obtained by considering a range of molecules that contain the same bond and calculating the average energy required to break that bond across those molecules. Average bond energies are useful when exact bond energies are not available or when dealing with more complex molecules where the specific environments and neighboring atoms can influence bond strengths. These values provide an estimation of bond energies that can be used for calculations and predictions. For example, the average bond energy of the C-C bond in organic compounds is an average value obtained from considering a variety of carbon-carbon bonds in different molecules. It represents the typical energy required to break a carbon-carbon bond in various contexts. It's important to note that average bond energies can vary to some extent depending on factors such as molecular structure, neighboring atoms, and the presence of functional groups. Therefore, they are approximate values that provide a general indication of bond strengths. In practical applications, average bond energies are often more commonly used due to the wide range of compounds encountered in chemical reactions. These values serve as valuable tools for estimating energy changes and making predictions about reaction outcomes. In summary, the distinction between exact and average bond energies is crucial in understanding the nature of bond strength. Exact bond energies are precise values obtained for specific bonds in individual molecules, while average bond energies represent the average energy required to break a particular type of bond across various compounds. Recognizing the difference allows for accurate calculations and interpretations of bond strengths in chemical reactions.

Reaction of Alkali metals with chlorine. Grade 10 SABIS ​ Generally: 2M (s) + Cl2(g) → 2MCl(s) alkali metal + chlorine → alkali metal chloride

Reaction of Alkali metals with hydrogen. Grade 10 SABIS ​ Generally: 2M(s) + 2H2(g) → 2MH(s) alkali metal + hydrogen → alkali metal hydride

when to use q=mc ΔT and when to use q=CΔT Grade 10 SABIS ​ The equation q=mcΔT is used to calculate the heat energy (q) transferred during a process where the temperature change (ΔT) occurs in a system with a constant mass (m) and specific heat capacity (c). This equation is applicable when we have a system with a known mass and want to determine the amount of heat energy gained or lost due to a temperature change. The specific heat capacity (c) represents the amount of heat energy required to raise the temperature of one unit mass of a substance by one degree Celsius (or Kelvin). For example, let's consider heating a sample of water. The equation q=mcΔT can be used to calculate the amount of heat energy required to raise the temperature of the water by a certain amount. Here, m represents the mass of the water, c represents the specific heat capacity of water (4.18 J/g·°C), and ΔT represents the change in temperature. On the other hand, the equation q=CΔT is used to calculate the heat energy (q) transferred during a process where the temperature change (ΔT) occurs in a system with a constant heat capacity (C). Heat capacity (C) is an extensive property that represents the amount of heat energy required to raise the temperature of an entire system by one degree Celsius (or Kelvin). It depends on the mass and specific heat capacity of the substance or substances in the system. When we want to calculate the amount of heat energy gained or lost by a system as a whole, regardless of the individual masses or specific heat capacities of the components, we can use the equation q=CΔT. This equation considers the total heat capacity of the system. For instance, in a calorimetry experiment, where the heat exchange occurs between two substances in a calorimeter, we use the equation q=CΔT to determine the amount of heat gained or lost by the combined system. The heat capacity (C) in this case represents the sum of the individual heat capacities of the substances involved. It's important to note that the specific heat capacity (c) is a property specific to a substance, while the heat capacity (C) is a property of a system. The specific heat capacity is typically used when dealing with individual components, while the heat capacity is used when considering the entire system. In summary, we use the equation q=mcΔT when calculating the heat energy transferred in a process with a constant mass and specific heat capacity. On the other hand, we use the equation q=CΔT when calculating the heat energy transferred in a process with a constant heat capacity, considering the entire system. The choice between the two equations depends on whether we are focusing on individual components with known masses and specific heat capacities or the system as a whole.

Mass of a Nucleus Grade 10 SABIS ​ 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.