Grade 8 Q2 Chem Reviewer PDF

GRADE 8 Q2 CHEM REVIEWER Made by: Kyra Tabitha D. Papa (with the help of Akisha Senrin O. Galang) Definitions Word Definition Examples Homogeneous A type of mixture that has a Seawater/Saltwate...

GRADE 8 Q2 CHEM REVIEWER Made by: Kyra Tabitha D. Papa (with the help of Akisha Senrin O. Galang) Definitions Word Definition Examples Homogeneous A type of mixture that has a Seawater/Saltwater uniform distribution; particles aren’t distinguishable, only has one phase Heterogeneous A type of mixture that does NOT Chocolate chip have a uniform distribution; cookies particles are distinguishable, has Mixed nuts two or more phases Colloid A mixture in which small insoluble Milk particles are dispersed Orange Juice throughout another substance. Suspension A mixture of relatively large Sand in water particles in which the particles are visible to the naked eye and are large enough for sedimentation. Solutions ❖ Solutions are homogeneous mixtures with two (2) or more substances: the solute (the substance that is being dissolved) and the solvent (the substance that does the dissolving). ❖ The solvent always has the largest quantity, no matter what kind of solution it is. Properties of Solutions ❖ Homogeneous mixture with two (2) or more substances ❖ Solute and solvent ❖ Transparent in nature ❖ Variable composition in terms of the ratio of solute to solvent ❖ Particles are uniformly distributed and will not change or separate with time. Classification based on State of Matter Type of Solution Solute Solvent Examples Solid Solid Solid Alloys (two or more kinds of metal combined) Copper (solvent) + Tin (solute) = Bronze Copper (solvent) + Zinc (solute) = Brass Copper (solute) + Silver (solvent) = Sterling Silver Nickel (solvent) + Chromium (solute) = Nichrome Liquid Solid Mercury (solute) + Silver (solvent) = Dentist’s Amalgam Liquid Solid Liquid Water (Liquid) + Coffee Powder (Solid) Liquid Liquid Alcoholic Beverages Alcohol in water (Antifreeze) Gas Liquid Water (Liquid) + Carbon Dioxide (Gas) = Carbonated Beverages Gas Gas Gas Air (78% Nitrogen, 21% Oxygen, 1% Other gasses) Water vapor + Air = Humid Air Classification based on Nature of Solvent ❖ Aqueous - solutions that use water as the solvent ❖ Non-aqueous - solutions that DON’T use water as the solvent Tincture - non-aqueous solution that uses alcohol as the solvent Solubility  ❖ Ability of a solid solute to dissolve in a liquid solvent ❖ Soluble - easily dissolved ❖ Insoluble - NOT easily dissolved Miscibility ❖ Ability of liquid substances to mix uniformly ❖ Miscible - mix uniformly ❖ Immiscible - DON’T mix uniformly and forms separate layers Polarity ❖ Polar - has both positive and negative charges ❖ Non-polar - NOT have both positive and negative charges “Like dissolves like” Substance 1 Substance 2 Soluble/Miscible Immiscible Polar Polar ✔️ Non-Polar Non-Polar ✔️ Polar Non-Polar ✔️ Electrolyte vs Nonelectrolyte (Liquid solutions) ❖ Electrolyte - liquid solutions capable of conducting electricity produces ions ❖ Nonelectrolyte - liquid solutions NOT capable of conducting electricity Factors that affect solubility ❖ Nature of solute and solvent - two substances that are similar in structure have a tendency to dissolve in each other. ex. : NaCl and water, the polar molecules of water immediately attach themselves to the salt crystals, which results in weakening the attraction between the sodium and chloride ions. ❖ Pressure - a factor that has no significant effect on the solubility of liquids and solids, but has a significant effect on the solubility of gas. Pressure ↑ Solubility of gas in liquid ↑  Henry’s Law - “The solubility of a gas in liquid is proportional to the pressure of the gas over the solution” ❖ Temperature - gaseous solutions in liquids are greatly affected by the changes in temperature. GAS: Inversely proportional Temperature ↑ Solubility of gas in liquid ↓ SOLID AND LIQUID: Directly proportional Temperature ↑ Solubility ↑ Factors that affect the rate of solution of solids in liquids ❖ Rate of solution of the solute is the amount of solute entering a solution per unit time. - Size of solute particles - Stirring - Heating Saturation - the amount of solute dissolved in a solution in a given amount of temperature. ❖ Unsaturated - holds less than the maximum amount of solute that can be dissolved in a given temperature. ❖ Saturated - holds the maximum amount of solute that can be dissolved in a given temperature. ❖ Supersaturated - holds more than the maximum amount of solute that is capable of being dissolved at a given temperature. Concentration and Dilution - ratio of the amount of solute and solvent in a solution. ❖ Concentrated - more solute than solvent (thick, viscous, and high density) ❖ Diluted - less solute than solvent (thin, low viscosity and low density) - two ways to describe concentration ❖ Qualitative - based on observable characteristics (appearance, smell, etc.) ❖ Quantitative - based on the specific amount of solute and solvent through problem solving. Percent (%) by mass and volume Formulas: % by mass - mass of solute / mass of solute + mass of solvent % by volume - mass of solute / mass of solution Molarity Molarity (M)- measure of concentration in terms of mole and is moles of a substance per liter (mol/L) of solution. mole - unit intended to express the amount of substance in a particular element. Avogadro’s number - 6.022 x 10²² amu - atomic mass unit Solving for molar mass Element: Step 1 Step 2 Step 3 Oxygen O 15.999 16g/mol Compound: Step 1 Step 2 Step 3 Step 4 Step 5 H₂O H₂, O 1.008 1 2 2 15.999 16 1 16 18g/mol Explanations for steps 4 and 5: Step 4 - Determine the amount of atoms of an element. (ex: H₂ has 2 hydrogen atoms) Step 5 - Multiply it to the rounded off atomic weight and add the two together. ! Don’t forget to write the unit. (g/mol) Calculating for the molarity Step 1: Calculate / find the molar mass of an element. (If not given) Step 2: Calculate the number of moles = mass of substance / molar mass Step 3 - Calculate for molarity: =moles of solute / liter of solution Unit: mol/L Provided by Teacher ❖ https://www.canva.com/design/DAGSVeHHrmU/970UPyvckvPBCnkR9YIzjg/edit (Presentation provided by Ma’am Zarate and the Student Teacher for Chemistry for October 3, 2024) ❖ https://docs.google.com/presentation/d/e/2PACX-1vRigDqKiLYhAiZtkSTTyYo47mdNICx1aacLBP0rgm5 3n4oQ0ER2xvu7-1ImEgkQTQ/pub?start=false&loop=false&delayms=3000&authuser=1 ❖ https://docs.google.com/presentation/d/e/2PACX-1vQ9xOQe3NJ-oFjEK_M0oGVEjGVTaeeMMriRcm0 Oq12084Nxf2YNIekbK321Vvedkw/pub?start=false&loop=false&delayms=3000&authuser=1 ❖ https://docs.google.com/presentation/d/1tV78CWi2eNpmFl_oFfsZlu40tejOXJ39/edit#slide=id.p2 ❖ https://www.youtube.com/watch?v=awMdCCidgOc