chem eta w_o review.pdf

End-Term-Assesment Reviewer °❀⋆.ೃ ࿔*:･ ──.✦ Chemistry as a Central Science Chemistry is the study of matter, and since matter is classified as anything that takes up space, matter is everything and everywhere thus making it applicable to any branch of science. Chemistry in Earth Science - universe was formed through the interaction of atoms - our atmosphere, the land and water, undergo changes in matter Chemistry in Physical Science - involves the structure of matter - the energy and work produced are interactions between components of matter Chemistry in Biology - All living organisms are made up of matter - Bodily functions of living organisms involve chemical processes ──.✦ Branches of Chemistry Analytical Chemistry - Studies the properties of chemical substances and the structure and composition of compounds and mixtures. This involves techniques and methods to analyze substances determining their composition, structure, and properties. —-- Applications of Analytical Chemistry ᡣྀིྀི Pharmaceuticals ᡣྀིྀི Environmental Monitoring ᡣྀིྀི Forensics ᡣྀིྀི Ensuring the Quality, Safety, and Compliance of Products and Processes ᡣྀིྀི Food Nutrients Organic Chemistry - Studies the chemical substances that contain carbon and hydrogen (C-H) bonds in combination with atoms such as oxygen, nitrogen, and sulfur. It focuses on the structure, properties, reactions, and synthesis of organic molecules, which include not only natural substances like proteins, carbohydrates, and lipids but also synthetic compounds like plastics and pharmaceuticals. —-- Applications of Organic Chemistry ᡣྀིྀི Pharmaceuticals ᡣྀིྀི Biotechnology ᡣྀིྀི Agriculture ᡣྀིྀི Environmental Science ᡣྀིྀི Forensic Science ᡣྀིྀི Plastics Inorganic Chemisty - Studies chemical substances that do not contain carbon-carbon bonds. It includes the study of metals, minerals, salts, and coordination compounds. —-- Applications of Inorganic Chemistry ᡣྀིྀི Materials Science ᡣྀིྀི Energy Storage and Conversion ᡣྀིྀི Metallurgy ᡣྀིྀི Electronics and Semiconductors ᡣྀིྀི Environmental Chemistry ᡣྀིྀི Mining Physical Chemistry - Interprets chemical processes in terms of physical properties of matter. It branch of chemistry that combines principles of physics and chemistry to study the behavior of matter at a molecular and atomic level. This focuses on understanding how chemical reactions occur, the energy changes involved, and the physical properties of materials. —-- Applications of Physical Chemistry ᡣྀིྀི Chemical Reaction Mechanisms ᡣྀིྀི Material Design and Nanotechnology ᡣྀིྀི Energy Storage and Conversion (e.g., batteries, fuel cells) ᡣྀིྀི Environmental Chemistry (pollutant behavior and cleanup) Biochemistry - Biochemistry is the branch of science that explores the chemical processes within and related to living organisms. It focuses on the molecular mechanisms that govern biological functions, including how cells produce energy, synthesize proteins, and how genetic information is regulated. —-- Applications of Biochemistry ᡣྀིྀི Medicine and Drug Development ᡣྀིྀི Biotechnology and Genetic Engineering ᡣྀིྀི Agriculture and Crop Improvement ᡣྀིྀི Nutritional Science ᡣྀིྀི Environmental Conservation (e.g., bioremediation) ᡣྀིྀི Molecular Biology and Genetics Environmental Chemistry - Environmental chemistry is concerned with matter and the environment. It focuses on understanding the effects of human activities on the air, water, soil, and ecosystems, as well as developing methods for pollution control and sustainable practices. —-- Applications of Environmental Chemistry ᡣྀིྀི Pollution Monitoring and Control ᡣྀིྀི Waste Management and Recycling ᡣྀིྀི Water Treatment and Purification ᡣྀིྀི Soil Remediation ᡣྀིྀི Air Quality Management ᡣྀིྀི Climate Change Research ᡣྀིྀི Sustainable Agriculture Practices Industry Chemistry - Industrial chemistry is concerned with the chemical properties in the industry. This focuses on the large-scale production and manufacturing of chemicals and materials. —-- Applications of Industrial Chemistry ᡣྀིྀི Chemical Manufacturing (e.g., fertilizers, plastics) ᡣྀིྀི Pharmaceuticals Production ᡣྀིྀི Food and Beverage Production ᡣྀིྀི Coatings and Adhesives Manufacturing ᡣྀིྀི Renewable Energy Production (e.g., biofuels) Polymer Chemistry - Polymer chemistry is the study of plastics and other chainlike molecules that consist of many smaller molecules linked together. This field encompasses the synthesis, characterization, and processing of polymers, as well as their physical and chemical properties. —-- Applications of Polymer Chemistry ᡣྀིྀི Plastics and Packaging Materials ᡣྀིྀི Textiles and Fibers ᡣྀིྀི Coatings and Paints ᡣྀིྀི Biomedical Devices and Materials ᡣྀིྀི Rubber and Elastomers Thermochemistry - Thermochemistry is the branch of chemistry that studies the relationships between chemical reactions and changes in energy, particularly heat. It focuses on understanding how energy is absorbed or released during chemical reactions, phase changes, and other processes.—-- Applications of Thermochemistry ᡣྀིྀི Energy Production and Conversion (e.g., combustion engines, fuel cells) ᡣྀིྀི Chemical Reaction Optimization ᡣྀིྀི Heat of Reaction ᡣྀིྀི Refineries ──.✦ Scientific Investigation Scientific Investigation is a systematic approach to solving problems or studying phenomena and communicating the results to the scientific community. –⟢ Scientific Method An organized process used by scientists to do research and verify the work of others. Steps in Scientific Method °❀⋆.ೃ ࿔*:･ 1. Observation - First necessary step in the scientific method - Observing changes in the environment - Involves usage of measuring instruments to obtain more accurate details. 2. Asking Questions - Developing questions or problems that can be solved through experimentation. - Involves brainstorming with people who have the same observation - Think about what you know and then state the problem 3. Conducting Research - Entails gathering information about your inquiry or problem - Information must be obtained through reliable sources. 4. Formulating Hypothesis - Creating a tentative, testable statement or prediction about what has been observed - Either accepted or rejected - A conditional statement that shows a presumed specific relationship between two observed variables - Ex; IF Jaime drinks 2 gallons of Dior Savauge, THEN he will start puking for 2 hours and could die. - Must be Specific and Measurable 5. Testing Hypothesis - Where the experiment is done - A carefully planned activity that is used to verify/test the hypothesis – The experiment must (a) indicate a thorough procedure (b) include a detailed list of materials (c) have a measurable outcome based on a set of experimental variable (d) have at least 3 trials 6. Recording and Analyzing Data - Gathering data using tables and spreadsheets allows for easy data recording - Taking videos and/or pictures of the experiment will also help document and analyze the experiment - Result can be presented in graph or chart and can be analyzed via equations or statistical tools. 7. Drawing Conclusions - Make conclusions based on observations which answer the inquiry question or problem - State whether the hypothesis is true or false - Include recommendations for further study and possible improvements to the procedure 8. Communicate Results - Results communicated through written or oral report - The report must include title, researchers, abstract, introduction, objectives, procedure, data, results, and conclusions. - Recommendations on the improvement in the conduct of the experiment and further study must be included. Experimental Variable °❀⋆.ೃ ࿔*:･ - The experimental variable is any factor, trait, or condition that can exist in a given experiment. Independent Variable °❀⋆.ೃ ࿔*:･ - An independent variable is the factor or condition that is manipulated or changed in an experiment to observe its effect on the dependent variable. Dependent Variable °❀⋆.ೃ ࿔*:･ - A dependent variable is the outcome or response that is measured in an experiment, and it changes in response to the manipulation of the independent variable. Controlled Variable °❀⋆.ೃ ࿔*:･ - A controlled variable is a factor in an experiment that is kept constant to ensure that any observed changes in the dependent variable are solely due to the manipulation of the independent variable. Example ! ⸜(｡˃ ᵕ ˂ )⸝♡ “What happens to the color of white soap when grape juice is added to it” Independent Variable Dependent Variable Controlled Variable - Kind of fruit - Change in the color of the - Soap brand soap water - Amount of water Independent Variable: - Grape Juice: This is the independent variable because it is the factor that is intentionally changed or manipulated in the experiment to observe its effect on the color of the soap. Dependent Variable: - Change in the Color of the Soap Water: This is the dependent variable because it is the outcome being measured in response to the addition of grape juice. The experiment aims to see how the grape juice affects the color of the soap. Controlled Variables: - Kind of Fruit:This variable needs to be kept the same to ensure that any color change is only because of grape juice and not other fruit juices, which could have different colors or effects. - Soap Brand: Keeping the soap brand constant ensures that the chemical composition and characteristics remain the same, preventing variability in the results that could arise from using different soap brands. - Amount of Water: The amount of water used must stay the same to ensure any color change is due to the grape juice and not because of differences in how much soap is mixed in. “What’s the effect of salt in the melting time of ice” Independent Variable Dependent Variable Controlled Variable - Amount of salt in ice - Time the ice melts - Temperature - Type of Water ──.✦Mathematical Skills In Chemistry Counting Numbers ⭑.ᐟ - These numbers greater than zero - These numbers are used in physically counting objects Defined Numbers ⭑.ᐟ - Involve a relationship between units and measurements - Ex; 1 foot = 12 inches - Ex; 36.5 mL. || 36 = known ,.5 = estimated Uncertainty in Measurements - All measurements are not exact to a certain degree. - Measuring tools may differ in numerical value for the same object and unit. - One person may also read a measurement differently These uncertainties are addressed by determining which digits in measurements are called significant digits or significant figures. The number of significant figures includes all certain digits plus one estimated digit. Rules for Determining Significant Figures 1. All nonzero digits are significant Ex; 342.4 in 56.92 g 123.319 L 2. All zeroes to the left of the nonzero digit are NOT SIGNIFICANT. These zeroes are called “placeholder zeroes” 0.07 mm 0.00028 mL 0.0369 m 3. Zeros between nonzero digits are insignificant 2.509 V 0.2001 ft 8300.02 s 4. Zeros that follow nonzero digits and are on the right of the decimal point are significant digits 9.00mm 8.2000 mL 54.030 C 5. Trailing zeros to the right of nonzero digits in numbers that contain no decimal point may or may not be significant. 200 g 3100 psi Example ˚ ˚⋆｡☆ Given Significant Figures Reasons 4.99 3 All non-zero digits are SIGNIFICANT 0.0745 3 All zeros to the left of the first nonzero digits are NOT SIGNIFICANT 1.920 4 Zeros that follow nonzero digits and are on the right of the decimal point are SIGNIFICANT 4.80002 6 Zeros in between significant numbers are SIGNIFICANT Scientific Notation ˚ ˚⋆｡☆ - It is a way of expressing numbers that are too big or too small to be conveniently written in decimal form. - It is expressed as any number between 1 and 10 multiplied by 10 raised to an exponent. A x 10^n | - wherein A = number equal to or greater than 1 but less than 10 - wherein n = the number of places the decimal point has been moved Rules in Scientific Notation ˚ ˚⋆｡☆ - The exponent is POSITIVE when the decimal moves to the left. 210 -> 2.1 x 10^2 -The exponent is NEGATIVE when the decimal moves to the right 0.021 -> 2.10 x 10^-2 Converting Scientific Notation to Standard Notation When the exponent is POSITIVE, you move the decimal point to the right When the exponent is NEGATIVE, you move the decimal point to the left Accuracy and Precision Precision - Precision means how close a group of measurements are to each other. If you measure something multiple times and get almost the same result each time, your measurements are precise, even if they aren't exactly correct. It’s more about being consistent than being right. Accuracy - Accuracy refers to how close a measurement is to the true or correct value. If a measurement is near the accepted value, they are considered accurate. Essentially, it’s about “hitting the target”. Fundamental Units of Measurement ‧₊˚❀༉‧₊˚. Components of a measured value. - Numerical Quantity - Unit of Measurement - Name of Substance Measured #Note ⭑.ᐟ Each of these must be included when the data is recorded. When one of the parts of a measured value is missing, accurate calculations/assumptions cannot be made. Ex; 56 oz. 56 = Numerical Value, oz = Unit of Measurement, Iced Coffee = Name of Substance Measurement - The process of comparing a quantity with a chosen standard. - These are obtained using tools and devices Two Classifications of Units of Measurement ‧₊˚❀༉‧₊˚. : Fundamental - Fundamental units are the basic building blocks of measurement that do not depend on other units. They represent the core physical quantities that can be measured directly. Examples of Fundamental Units include; Length, Mass, Time, and Electric Current : Derived - Derived units are those that are formed by combining fundamental units according to algebraic relationships between physical quantities. They depend on the fundamental units and can be expressed as products or quotients of these base units. Examples of derived units include: Velocity, Acceleration, Force, and Pressure. Fundamental Units of Measurement —---------------------------------------------- QI Base Unit Quantity Name Symbol Time seconds s Length meters m Mass kilograms kg Temperature kelvin K Amount of Substance moles mol Electric Current amperes A Luminous Intensity candelas cd Metric Unit of Measurement - A system of measurement commonly used in science and many countries. - Evolved into the International System of Units - Key Features include: a. Decimilzation b. A system of prefixes c. A standard in terms of an invariable physical measurement - Has a base unit from which all units in the system are derived. - Combines prefix and base units. Note; Take note of this as you MIGHT need to memorize it for the test. Conversion of Measurements ‧₊˚❀༉‧₊˚. – Conversion Factor ! #: Conversion is the ratio of equivalent values of quantities having different units. #: One method that can be used is the dimensional analysis or factor label method. – Dimensional Analysis #: Dimensional analysis is the study of the relationships between different physical quantities by identifying their base dimensions and units of measurement, allowing for the conversion of units and verification of the dimensional homogeneity of equations. Unit Conversion Example Step 1 ; Determine the given and the desired unit. Step 2 ; Identify the conversion factor to be used Step 3 ; Use dimensional analysis # Given —------------Desired 7g = ___________ kg # Conversion Factor : 1kg = 10^3 g # Solution : 7g [1kg/10^3g] = 0.007 kg. # Given —------------Desired 924 cm = ___________ m # Conversion Factor : 1m = 10^2 cm # Solution : 924 cm [1m/10^2 cm] = 9.24 m States and Phase Changes of Matter ‧₊˚❀༉‧₊˚ Matter - matter is defined as anything that has mass and takes up space. – Classifications of Matter ‧₊˚❀༉‧₊˚ States – Solid, Liquid, Gas Composition - Pure substance and Mixture States of Matter; A solid. A solid state of matter encompasses the following. (a) Has a definite shape or volume (b) Is hard to compress (c) Has compact particles (d) Has high density (e) Might not conform to the shape of the container State of Matter; Liquids. A liquid state of matter encompasses the following. (a) has no definite shape (b) has a definite volume (c) has less compact particles (d) flows (e) has low density relative to solids State of Matter; Gasses. A gaseous state of matter encompasses the following. (a) Has an indefinite shape and volume (b) Is highly compressible (c) Has particles that are far apart (d) Has low density (e) Conforms to the shape of the container Matter can change physically or chemically - matter whether solid, liquid, or gas changes its physical state. - only physical qualities are changed - no alterations in its chemical composition. Phase Changes ‧₊˚❀༉‧₊˚ Melting (solid to liquid) - The solid particles absorb energy while the temperature increases, making the particles vibrate strongly which weakens their attraction to each other. Freezing (liquid to solid) - As the heat leaves, the particles move slowly thus making their attraction stronger and forming orderly arrangements. Sublimation (solid to gas) - Due to abrupt changes in temperature and pressure, the particles of solid instantly loosen up to form gasses. Deposition (gas to solid) - Due to abrupt changes in temperature and pressure, the gas particles instantly change to solid without going through the liquid state. Evaporation (liquid to gas) - Evaporation happens when the liquid phase changes to the gas phase at a temperature above the boiling point at a given pressure. Condensation (gas to liquid) - Condensation happens when gas (water vapor) turns to a liquid state. Pure Substances and Mixtures —----------------------------------------------------------------------------------------------- Pure Substances - Properties ⋆౨ৎ˚⟡˖ ࣪ - can be an element or a compound - chemically combined - has the same properties throughout a given sample - has a definite and unchanging chemical composition Mixtures - Properties ⋆౨ৎ˚⟡˖ ࣪ - two or more pure substances that are physically combined - properties are inconsistent throughout a given sample. - has an indefinite and changing composition - can be physically separated - can be either homogenous or heterogeneous Elements, Compounds, Homogeneous, and Heterogenous Mixtures ִֶָ ࣪ ˖ִֶָ ་—---------------------------------------------- Elements (Properties) ໒꒰ྀ ིっ˕ -｡꒱ྀ ི১ - Composed of one basic unit of matter called an atom. - Cannot be broken down into smaller substances by physical or chemical means. - 118 known elements ] \ Metal Properties - ˙. ꒷. ˙— - This element is normally solid at room temperature except mercury (Hg) - Measure of the ease at which an electric charge or heat can pass through a metal - Material’s ability to be hammered or rolled into thin sheets - Material’s ability to be stretched into thin wires - Ex; Nickel, Silver, Cobalt Nonmetal Properties ˙. ꒷. ˙— - An element that does not have the properties of a metal. - They exist in solid, liquid, or gaseous form - Brittle - Poor thermal and electrical conductivity - Little luster and seldom reflect light - Ex; Bromine, Neon, Sulfur Metalloid Properties ˙. ꒷. ˙— - An element that has physical and chemical properties of both metal and nonmetal Compounds (Properties) ໒꒰ྀ ིっ˕ -｡꒱ྀ ི১ - The names of most compounds are derived from the names of the elements that compose them. - They can be separated into their constituent elements and/or compounds through chemical reactions. - Each compound has a set of properties different from the elements that compose them - In terms of its particulate nature, compounds are made up of molecules - Ex; Formation of Salt Sodium (solid) + Chlorine (gas) = Sodium Chloride (solid) - Compounds follow the Law of Definite Proportions - A compound is always composed of the same elements in the same proportion by mass no matter how large or small the sample. - The mass of the compound is equal to the sum of the masses of the elements that make up the compound. Mixtures (Homogenous and Heterogenous) - Homogenous - Exists in a single phase - Has visibly indistinguishable parts - Usually called solutions - Uniform composition and appearance throughout a given sample - Components can’t be separated physically - Heterogenous - Non-uniform type of mixture - Exists in two or more phases - Has visibly distinguishable parts - Components can be separated physically - Two types of Heterogenous Mixtures —- suspension and colloid Suspension: large-sized particles, particles settle Colloid: Medium-sized particles, particles don’t settle, particles of which the colloid is made are called dispersed material, any colloid consisting of a solid dispersed in gas is called a smoke, a liquid dispersed in a gas is referred to as a fog. Techniques in Separating Mixtures 1. Filtration - commonly used for solid-liquid mixtures - The mixture is poured into filter paper - The solid particles (residue) remain in the filter paper - The liquid (filtrate) passes through the filter paper 2. Evaporation - commonly used for solid-liquid mixtures - Employs the differences in boiling point of the components - Done if you want to recover 1 component 3. Distillation - commonly used for solid-liquid mixtures and liquid-liquid mixtures - Employs the differences in boiling point of the components - Done if you want to recover both components 4. Magnetic Separation - Commonly used for solid-solid mixtures - Employs the difference in magnetic properties 5. Chromatography - Separation of a mixture by passing using a solution/suspension - Involves 2 components: The stationary phase (does not move) and the mobile phase (component that moves) Solutions (Types of Solutions and Factors Affecting Solubility) - Solution - Describes homogenous mixtures composed of two or more substances - Has a uniform composition and appearance throughout the sample - Components of a Solution Solute - The component that is dissolved in a solution - Typically present in lesser amounts in a solution Solvent - The component that is used to dissolve the solute in a solution - Typically present in larger amounts in a solution Types of Solution (Phase and Concentration) - Phase (State) of Solution - Solid, Liquid, Gasses Solid Solutions ⊹₊ ˚‧︵‿₊୨୧₊‿︵‧ ˚ ₊⊹ Solute Solvent Examples Gas Solid Hydrogen in Palladium Liquid Solid Liquid Mercury in Solid Palladium Solid Solid Steel Liquid Solutions ⊹₊ ˚‧︵‿₊୨୧₊‿︵‧ ˚ ₊⊹ Solute Solvent Examples Gas Liquid Carbonated Drinks Liquid Liquid Rubbing Alcohol Solid Liquid Salt in Water Gaseous Solutions ⊹₊ ˚‧︵‿₊୨୧₊‿︵‧ ˚ ₊⊹ Solute Solvent Examples Gas Gas Air Liquid Gas Water Vapor in Air Solid Gas Mothballs Sublimed in Water Types of Solution (Concentration of Solution) Qualitative or Quantitative Qualitative - a substance or system based on observable properties rather than numerical measurements. There are 2 types of qualitative solutions. - "dilute" (low amount of solute) - "concentrated" (high amount of solute) Quantitative - a substance/solution that involves specific numerical measurements, such as the exact concentration/amount of a solute in a solution. - “unsaturated” (less amount of solute dissolved in the solution) - “saturated” (contains the maximum amount of solute that the solvent can dissolve) - “supersaturated” (excess amount of solute dissolved in a solvent by heating) Factors Affecting Solubility ⊹₊ ˚‧︵‿₊୨୧₊‿︵‧ ˚ ₊⊹ Solubility - The maximum amount of substance that dissolves in a given amount of solvent. - Primarily used for solid-liquid solutions, when liquid-liquid is being discussed, “miscibility” is used. Solubility of Solute is influenced by: 1. Nature of Solute and Solvent This pertains to the Polarity of the Solute and Solvent Polarity = How atoms of a compound are bound to each other. LIKES DISSOLVE LIKE. Ex; Water is a POLAR solvent and will dissolve POLAR solutes 2. Temperature Solids dissolve faster in higher-temperature liquids Gasses dissolve faster in a solvent of lower temperatures 3. Pressure A small change in pressure won’t affect the solubility of solids and liquids, however, if more pressure is added, the solid will eventually dissolve. - Pressure has a significant effect on gasses. The greater the pressure, the more a gaseous solute is dissolved in a solvent. 4. Particle Size Solubility is faster when solute particles have more surface and are exposed to the solvent. Components of a Solution A solution is composed of a solute and solvent and can be described as qualitative (diluted and concentrated) and quantitative (unsaturated, saturated, supersaturated) Expressing Concentration of a Solution Molarity Moles - A unit of measurement that denotes the amount of a substance. Molarity = moles of solute —-------------------------------- —---------- liters of solution #note! The unit for molarity is moles/L or M. CAPITALIZED M ALWAYS. Ex; An intravenous (IV) solution contains 0.03 moles of glucose (C6H12O6). What is the molarity of a 1.5L solution? Given: volume of solution = 1.5L - Moles of glucose = 0.03 mole Solution: molarity = moles of solute/liters of solution - 0.03 moles/1.5L Required: Molarity Answer: Molarity = 0.02 M. #Note! Always include M. Ex; A 0.50 M aqueous solution contains 1.5 moles of hydrochloric acid (HCL). How many liters of solution does the aqueous solution have? Given: Molarity = 0.50M Moles of HCL = 1.25 Moles Required: L of Solution Solution: Let x be the liters of solution. 1. Substitute the given. 1.25 moles/x 2. Cross multiply. 0.50M = 1.25 moles/x 0.50M (x) = 1.25 moles. 3. Isolate x in one side of the equation. x= 1.25 moles/0.50 mol/L Answer: x=2.5 L of solution Molality Molarity = moles of solute —-------------------------------- —---------- kg of solvent #Note! The unit for molality is moles/kg or m. ONLY USE SMALL m FOR MOLALITY. Ex; What is the molality of a solution that contains 0.034 mol of a sodium sulfate (Na2SO4) dissolved in 1,000g of water? Given: moles of Na2SO4 = 0.34 moles - Mass of water = 1000 grams #Note: 1kg = 1000g Solution: Molality = Moles of solute/Kg of solvent Molality= 0.34 moles/1kh Required: molality Answer: Molality = 0.34 m Ex; How many moles of calcium chloride (CaCl2) would be dissolved in 0.250 kg of water if the molal concentration of the solution is 0.500 mole/h Given: mass of water=0.250 kg Molality = 0.500 mole/kg Solution: Let x be the moles of CaCl2 1. Substitute the given. 0.500 mol/kg = x/0.250 kg 2. Cross multiply. (0.500 mol/kg) (0.250 kg) = x Required: moles of CaCl2 Answer: x = 0.125 mole of CaCl2 Reviewer Portion ⭑.ᐟ Answer this in a separate document or your notebook :3 1. A solution contains 0.10 moles of sodium chloride (NaCl) dissolved in 0.25 liters of water. What is the molarity of the solution? - Given: Volume of solution = 0.25 L Moles of NaCl = 0.10 moles - Required: Molarity - Solution: 2. A 2.0 M aqueous solution contains 0.80 moles of potassium hydroxide (KOH). How many liters of solution does this solution have? - Given: Molarity = 2.0 M Moles of KOH = 0.80 moles - Required: Volume of solution - Solution: 3. A solution has a volume of 3.5 L and contains 1.75 moles of sulfuric acid (H₂SO₄). What is the molarity of the solution? - Given: Volume of solution = 3.5 L Moles of H₂SO₄ = 1.75 moles - Required: Molarity - Solution: 4. What is the molality of a solution that contains 0.25 mol of glucose (C₆H₁₂O₆) dissolved in 0.500 kg of water? - Given: Moles of glucose = 0.25 moles Mass of water = 0.500 kg - Required: Molality - Solution: 5. How many moles of potassium nitrate (KNO₃) would be dissolved in 2.0 kg of water if the molal concentration of the solution is 1.5 m? - Given: Mass of water = 2.0 kg Molality = 1.5 m - Required: Moles of KNO₃ - Solution: 6. What is the molality of a solution that contains 0.85 mol of ammonium chloride (NH₄Cl) dissolved in 0.750 kg of water? - Given: Moles of NH₄Cl = 0.85 moles Mass of water = 0.750 kg - Solution: - Required: Molality Expressing Concentration of Solution ٩(ˊᗜˋ*)‫♡و‬ - Percent by Mass % mass = mass of solute/mass of solution x 100 #note! Mass of solution = mass of solute + mass of solvent % mass = mass of solute/mass of solute + mass of solvent x 100 Ex; To maintain a sodium chloride concentration similar to ocean water, an aquarium must contain 3.60 grams of NaCl per 100.0 grams of water. What is the percent by mass of NaCl in the solution? Given: Mass of NaCl = 3.60g - Mass of water = 100.0g Required: %mass of NaCl Solution: %mass= mass of solute/mass of solute+mass of solvent x 100 %mass = 3.60g/3.60g + 100.0 g x 100 Answer: %mass = 3.47% Ex; Baking soda is used as an instant relief for acid reflux. A 3.40% by mass baking soda (NaHCO3) solution must be prepared to relieve acid reflux. How many grams of sodium bicarbonate must be added to 118 grams of water in order to reduce acid reflux? Given: mass of water (solvent) = 118g Solution: %mass of NaHCO3 = 3.40% Let x be the mass of NaHCO3 1. Substitute the given. 3.40%= x/x+118 g x 100 2. Divide 3.40 by 100. 0.034 = x/x+118g 3. Cross multiply. 0.034(x+118)=x - 0.034x + 4.012g = x 4. Combine similar terms. (NOTE: x has a coefficient of 1) - 4.012 g = x -0.034x - 4.012 g = 0.966x 5. Isolate x on one side of the equation. x= 4.012 g/0.966 Answer: x=4.15 g of NaHCO3 Percent by Volume %volume = volume of solute/volume of solution x 100 #Note! Volume of solution = volume of solute + volume of solvent volume of solution = volume of solute + volume of solvent x 100 Ex; What is the percent by volume of ethanol in a solution that contains 45.00 mL of ethanol dissolved in 125.0 mL of water? Given: volume of ethanol = 45.00 mL - volume of water = 125. mL Solution: %volume = volume of solute/volume of solute + volume of solvent x 100 %volume = 45.00 mL/45.00 + 125.0 mL x 100 Required: %vol of solution Answer: %volume = 26.47 Ex; If 18.0 mL of methanol is used to make an aqueous solution that is 15% methanol by volume, how many mililiters of solution is produced? Given: Volume of methanol = 18.0 mL % methanol by volume = 15% Solution: % volume = volume of methanol/volume of solution x 100 Volume of solution = 18.0 mL / 15 x 100 Required: Volume of solution Answer: Volume of solution = 120 mL

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