Search Results

Sublimation The process of a substance changing directly from a solid to a gaseous state at a specific temperature.

Observations for the reaction of alkali metal with water: Grade 10 SABIS  Piece of metal floats (alkali metals have low density).  Piece of metal darts around.  A hissing sound is heard due to the evolution of a gas.  If red litmus paper is dipped in the solution, the paper turns blue due to the formation of the alkali metal hydroxide.  If few drops of phenolphthalein indicator are added to the water solution turns pink due to the formation of alkali metal hydroxide.  If the gas produced is tested with a lit splint, it burns with a squeaky pop sound.

Pressure The force applied per unit area.

Evaporation The process of a substance changing from a liquid to a gaseous state at a specific temperature.

Hess's Law Definition A Level Chemistry CIE Hess’s Law states that: This means that whether the reaction takes place in one or two steps, the total enthalpy change of the reaction will still be the same

Endothermic Grade 10 SABIS SABIS

6. The process of cooling liquid paradichlorobenzene until it Grade 10 SABIS SABIS

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.

Endothermic Reaction Grade 10 SABIS SABIS Is a reaction which absorbs heat from the surrounding. As heat is absorbed, the temperature of the surrounding decreases. Decomposition reactions like electrolysis of water, heating a substance, melting, vaporization and sublimation are examples of endothermic processes

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). Grade 10 SABIS

Reaction of Alkali metals with water. Grade 10 SABIS Generally: 2M(s) + 2H2O(l) → 2M+ (aq) + 2OH- (aq) + H2(g) alkali metal + water → alkali metal hydroxide + hydrogen Observations for the reaction of alkali metal with water:  Piece of metal floats (alkali metals have low density).  Piece of metal darts around.  A hissing sound is heard due to the evolution of a gas.  If red litmus paper is dipped in the solution, the paper turns blue due to the formation of the alkali metal hydroxide.  If few drops of phenolphthalein indicator are added to the water solution turns pink due to the formation of alkali metal hydroxide.  If the gas produced is tested with a lit splint, it burns with a squeaky pop sound.

Recall the expressions for gravitational potential and kinetic energy of an object Grade 10 SABIS Gravitational Potential Energy: Gravitational potential energy is the energy possessed by an object due to its position in a gravitational field. The expression for gravitational potential energy (PE) is given by the equation: PE = mgh where m represents the mass of the object, g represents the acceleration due to gravity, and h represents the height or vertical distance of the object from a reference point. For example, if we consider a ball of mass m that is lifted to a height h above the ground, the gravitational potential energy of the ball is given by the product of its mass, the acceleration due to gravity, and the height it is lifted to. Kinetic Energy: Kinetic energy is the energy possessed by an object due to its motion. The expression for kinetic energy (KE) is given by the equation: KE = (1/2)mv^2 where m represents the mass of the object and v represents the velocity of the object. If we consider the same ball that was lifted to a height and then released, as it falls downward, its potential energy is converted into kinetic energy. The kinetic energy of the ball is given by half the product of its mass and the square of its velocity. The expression for kinetic energy shows that the kinetic energy of an object is proportional to its mass and the square of its velocity. This means that an object with a larger mass or a higher velocity will possess more kinetic energy. It's important to note that both gravitational potential energy and kinetic energy are scalar quantities, meaning they have magnitude but no specific direction. They are both measured in units of energy, such as joules (J). In summary, the expressions for gravitational potential energy and kinetic energy provide insights into the energy possessed by an object. Gravitational potential energy is determined by the mass of the object, the acceleration due to gravity, and its height from a reference point. Kinetic energy, on the other hand, depends on the mass of the object and its velocity. Understanding these expressions helps us analyze and quantify the energy changes associated with the position and motion of objects in various scenarios.