Section 2 (1) PDF - Chemistry Notes

2.1 Pure Substances and Mixtures 1 2.1 Pure Substances and Mixtures Matter can also be classified as a pure substance or mixture. A pure substance is made up of one type of matter and has a unique set of characteristics or properties. For example, aluminum foil, baking soda, and distilled water....

2.1 Pure Substances and Mixtures 1 2.1 Pure Substances and Mixtures Matter can also be classified as a pure substance or mixture. A pure substance is made up of one type of matter and has a unique set of characteristics or properties. For example, aluminum foil, baking soda, and distilled water. A pure substance can be an element (Au gold) or a compound (H2O - water) A mixture is two or more substances mixed together. Homogeneous Appears as all one substance. Ex. Cola Heterogenous You can see the different substances that make up the mixture. Ex. chocolate chip cookie. 2 Mixtures A mechanical mixture is heterogeneous where you can see two or more substances mixed together. heterogenous homogeneous A solution is homogeneous where it all appears to be one substance. Ex. Cola A suspension is a cloudy mixture in which droplets or tiny pieces of one substance are held within another substance. If you leave a suspension undisturbed, its parts will usually separate out. Muddy water is an example of a suspension A colloid is also a cloudy mixture but the droplets or tiny pieces are so small that they do not separate out easily. Homogenized milk is a colloid of tiny cream droplets in whey. 3 Introduction to Elements s m o At Mo l es l u ec ds n ou p m Co A Atomic Number is the number of protons in the nucleus, thus the atoms total positive charge. The Atomic Weight is the weighted average of all the neutrons and protons in the nucleus. 4 Protons, Neutrons, and Electrons A proton is a stable particle with a positive + charge. A neutron is a particle with a mass only slightly larger than a proton and has no charge (neutral). An electron is a negatively charged particle. All three are referred to as subatomic particles because they are smaller than atoms. 5 Bohr Model Diagram Silicone (Si) 6 Compounds Explained A compound is made of two or more different elements. They are held together by strong bonds called chemical bonds. Only the valance (outer shell electrons) combine. 7 Cation vs. Anions An ion is an atom or groups of atoms. An anion is a negatively charged ion. A cation is a positively charged ion. 8 Paper Chromatography Paper chromatography is a simple and cost-effective method of separating the components of a mixture. If the fluid is a pure substance, it will move up a strip of filter paper to one level. If the fluid is a solution, the different substances in it will move up the paper to different levels 9 2.2 Concentration and Solubility Dissolving one substance into another makes a solution. The substance that dissolves is called the solute. The substance that does the dissolving is called the solvent. 10 In a concentrated solution, there are large amounts of solute in the solvent. For example, you may have made orange juice from frozen juice concentrate. The concentrate has a large amount of orange solids (solute) in a small amount of water (solvent). You add water to make a diluted solution. A diluted solution has small amounts of solute in the solvent. So the orange juice you drink is actually a diluted solution. 11 Measuring Concentration The concentration of a solution tells you the amount of solute dissolved in a specific amount of solvent. 50 grams of solute dissolved in 100 ml of solvent 50g / 100ml 12 Comparing Concentration In order to compare different concentrations between solutions, we MUST measure in the same units. A. 10 g of salt in 50 ml of water (10g/50ml) B. 25 g of salt in 100 ml of water (25g/100ml) 10 = x 50 100 = 10 x 100 = 20g / 100ml 50 25g / 100ml Compare at 100ml. B has the higher concentration 13 Saturated, Unsaturated and Supersaturated Solutions 14 Saturated, Unsaturated & Supersaturated Solutions Solubility is the maximum amount of solute you can add to a fixed volume of solvent at a given temperature. This is referred to as the saturation point. No more solute can be dissolved in the given volume of solvent at a given temperature. Insolubility is the inability of a solute and solvent to form a solution. 15 2.3 Factors Affecting Solubility Solubility is the maximum amount of solute you can add to a fixed volume of solvent at a given temperature. Three factors affect solubility. 1. Type of Solute 2. Type of Solvent 3. Temperature 16 Why is knowing solubility important? Knowing solubility is important because it helps us understand how different substances interact with each other in various solutions. This knowledge is crucial in fields such as chemistry, pharmaceuticals, and environmental science, where the solubility of a substance can affect its effectiveness, toxicity, and environmental impact. Additionally, understanding solubility can aid in the development of new products and technologies, as well as in the optimization of existing processes. 17 TYPES OF SOLUTES & SOLVENTS Water is the most common type of solvent. (aqueous solution) 18 SOLUBILITY CHANGES with TEMPERATURE The solubility of solutes is dependent on temperature. The solubility of solutes in solvents could be increased or decreased by increasing or decreasing temperature, Solubility increases temperature increases for most solutions. For example, at 25°C, you can dissolve 36.2 g of salt in 100 mL of water, but at 100°C, you can dissolve 39.2 g of salt in 100 mL of water. For gas, solubility decreases as temperature increases. 19 Saturated and Unsaturated Solutions Lab Temperature & Solubility Lab 20 THERMAL POLLUTION ● ● ● ● ● ● ● Industrial plants use water in their processes. They draw water from a lake or river. The water is warmer than when it was take from the lake when used in the industrial process. This warmer water is then returned to the lake or river. This warmer water now has less oxygen. As the temperature of water increases the amount of oxygen (gases) decreases. The decrease in oxygen results in a decrease in organisms that rely on oxygen, which in turn affects all other living things within and between ecosystems. 21 THERMAL POLLUTION SOURCES 1. THERMAL OR NUCLEAR POWER GENERATING PLANTS are the most important source of thermal pollution as these contribute as much as 75 percent heat discharged by the heated effluents to the body of stream water. 2. INDUSTRIES generating electric power require large amounts of cooling water for removal of heat, Industries like textiles, paper, pulp, sugar release lesser heat into the receiving water. 3. Domestic and Municipal Sewage discharging into a running stream with or without treatment also contribute to thermal pollution as their temperature is generally 4 degree- 8 degree Celsius higher than that of the receiving stream water. 22 THE THERMAL POLLUTION SOLUTIONS 1. COOLING TOWERS are used to cool the water from industry prior to being placed back into lakes and rivers. 2. ARTIFICIAL WETLANDS are built to hold the water from industry. 3. ESTABLISHMENT OF REGULATIONS & GUIDELINES are instituted to reduce the discharge of heated water into aquatic environments. 4. RENEWABLE ENERGY SOURCES to replace the need for fossil fuels such as geothermal, solar, hydroelectric and wind power. 23 THE PARTICLE MODEL OF MATTER The particle model has four main points that describe the structure of matter. Using this model, you will be better able to explain the properties of mechanical mixtures and solutions. 24 25 HOW THE PARTICLE MODEL EXPLAINS MIXING SUBSTANCES Two different liquids are made up of different sized particles. When one liquid is poured into another, it fills the spaces between the larger particles. This occurs between ethanol and water. 26 HOW THE PARTICLE MODEL EXPLAINS MOVEMENT As temperature increases, the movement increases As the temperature decreases, the movement decreases. 27 HOW THE PARTICLE MODEL EXPLAINS ATTRACTION of PARTICLES Some particles of a substance have a greater attraction to particles of a different substance than those of their own. Potassium permanganate is more attracted to water particles than to each other. The solute dissolves. 28 HOW THE PARTICLE MODEL EXPLAINS ALL PARTICLES HAVE SPACES BETWEEN THEM Every cluster of particles have space between them no matter the state in which they exist. 29 FACTORS AFFECTING THE RATE OF DISSOLVING 1. Temperature 2. Size of the Pieces 3. Stirring 30 FACTORS AFFECTING THE RATE OF DISSOLVING 1. Temperature 31 FACTORS AFFECTING THE RATE OF DISSOLVING 2. Size of the pieces 32 FACTORS AFFECTING THE RATE OF DISSOLVING 3. Stirring 33