GUÍA UNAM - QUÍMICA (TEMA 2. AGUA) [60 Preguntas]

💯 UNAM GUIDE · CHEMISTRY · TOPIC 2. WATER 👇👇 EXTRA QUESTIONS BELOW 👇👇 ► TOPIC 2. WATER − Water composition and molecular structure − Polarity and hydrogen bonds. − Physical properties: boiling and melting points, specific heat capacity. − Chemical properties: bond type, water's solvent capacity (power). − Acids and bases. − Classification by conductivity: strong and weak. − Differentiation of substances according to their pH. − Indicators and pH. − Solutions or dissolutions. − Concept of solute and solvent. − Water pollution. − Main pollutants: physical, chemical, and biological. − Generating sources: industrial, urban, and agricultural. ✅ Study hard and take care of yourself ✌️ 👇👇 EXTRA QUESTIONS 👇👇 ►Water is a molecule: R = Inorganic and thermoregulatory. ►The preservation of the climate and the species that inhabit the Earth is thanks to which property of water: R = Heat capacity. ►Melting point, boiling point, and density are examples of properties: R = Specific. [They are what differentiate one body from another] ►Freezing point is an example of a property. R = Intensive. [It does not depend on the amount of matter] ►Water is a polar solvent due to: R = The angular structure of its molecules. ►Water's angular structure helps it: R= The formation of hydrogen bonds. ►Why does a glass of cold water get wet on the outside? R= Water from the environment condenses. ►What is the lowest possible temperature? R= –273.15 °C ►How many °C is 32 °F? R= 0 °C. [The formula is T°C = (T°F – 32)/1.8] ►Transform 2.728 K to the Celsius scale. R= –270.272 °C [The formula is T°C = TK – 273] ►Relate the substances. Acid – Higher concentration of H+ ions Base – Higher concentration of OH- ions Neutral – Equal concentration of H+ and OH- ions ►Substance with neutral pH (pH = 7) R = Water ►A solution with a pH of 8 is a substance: R = Weak base. ►Substances that are capable of changing color when the pH changes. R = Indicators. ►When electricity is applied to an aqueous solution containing nitric acid HNO3, it is a good conductor because it is: R = A strong electrolyte. ►To determine the concentration of a substance expressed in terms of molarity, it is necessary to know: R = Volume of solvent, molecular weight, and the amount of solute. ►What is the molarity of a solution containing 20 g of NaOH in 2 L of solution? A = 0.25 M. ►A solution contains 2.5 g of sodium chloride (NaCl) and 15 g of glucose (C6H12O6) dissolved in 100 g of water. What percentage of glucose is present in the solution? A = 12.8%. [Add the masses of the solutes and the solvent (2.5 + 15 + 100 = 117.5). Then divide the mass of the solute (glucose) by the mass of the solution obtained and multiply by 100 (15/117.5 x 100 = 12.76%). The result is close to the correct answer.] ►When 100 g of a 15% sodium chloride solution is mixed with 200 g of a 25% sodium chloride solution. The percentage concentration of the resulting solution is: R = 21.7%. ►If you want to prepare 500 mL of a 15% by volume solution, determine the amount of solute required: R = 75 mL. ►The amount of mL of concentrated HCl (37% by weight and d = 1.14 g/mL) that must be measured to prepare 250 mL of 1.4 M HCl(aq) is: R = 30.3 mL. #UNAMGuide #UNAMExam #UNAM