9th Chemistry Chapter 6: Solution

Question 1. What is an unsaturated solution?
Answer:

An unsaturated solution is a solution that contains less solute than the amount needed to form a saturated solution at a given temperature and pressure. It has the capacity to dissolve more solute.

Question 2. Explain the difference in particle size between solutions, suspensions, and colloids.
Answer:

Solutions: Solute particles in solutions are molecular or ionic in size, typically less than 1 nanometer.

Suspensions: Solute particles in suspensions are larger and can be seen with the naked eye. They settle out upon standing.

Colloids: Solute particles in colloids are intermediate in size between those in solutions and suspensions. They are large enough to scatter light but small enough to remain dispersed and not settle out.

Question 3. What is the role of pressure in the solubility of gases in liquids?
Answer:

In general, the solubility of gases in liquids increases with an increase in pressure. This is described by Henry’s law, which states that the solubility of a gas is directly proportional to the partial pressure of the gas above the solution. An example is the increased solubility of oxygen in water under high pressure, as seen in soda or sparkling water.

Question 4. Explain the concept of a colloid.
Answer:

A colloid is a type of mixture where one substance is dispersed evenly throughout another substance at the microscopic level. Colloidal particles are larger than individual molecules but smaller than particles in a suspension. They do not settle out upon standing and exhibit the Tyndall effect, where they scatter light. Examples include milk, fog, and whipped cream.

Question 5. How does the concentration of a solution affect its properties?
Answer:

The concentration of a solution, which is the amount of solute dissolved in a given amount of solvent, affects various properties such as boiling point, freezing point, osmotic pressure, and conductivity. Generally, as the concentration increases, these properties change accordingly. For instance, higher concentrations typically result in higher boiling and freezing points, increased osmotic pressure, and greater conductivity.

Question 6. Explain the concept of "precipitation" in the context of solubility.
Answer:

Precipitation occurs when a solution becomes supersaturated, and the excess solute particles come together to form solid particles that settle at the bottom. This can happen when the solubility limit of a solute is exceeded or when there is a sudden change in temperature or pressure. An example is the formation of solid calcium carbonate (CaCO3) when calcium ions and carbonate ions react in a solution.

Question 7. Explain the concept of a solid solution with an example.
Answer:

A solid solution is formed when a solute is uniformly distributed in a solid solvent. An example is steel, where carbon atoms are dissolved in iron. Brass, which is an alloy of copper and zinc, is another example of a solid solution.

Question 8. Provide an example of a supersaturated solution.
Answer:

Phase transitions in solids occur when a material undergoes a change in its crystal structure or physical state due to changes in temperature, pressure, or other external factors. Examples include melting, freezing, sublimation, and deposition, which are characteristic phase transitions observed in various solids.

Question 9. How do solutions, suspensions, and colloids respond to filtration?
Answer:

Solutions: Solutions pass through filter paper, leaving behind any insoluble impurities.

Suspensions: Suspensions may clog filter paper due to the large size of the solute particles, and only the liquid portion passes through.

Colloids: Colloids do not pass through filter paper due to the intermediate size of the solute particles. However, they can be separated using specialized techniques like ultrafiltration or centrifugation.

Question 10. What is the difference between miscible and immiscible liquids?
Answer:

Miscible liquids: Liquids that are completely soluble in each other in any proportion are considered miscible. Example: ethanol and water.

Immiscible liquids: Liquids that do not dissolve in each other and separate into distinct layers are considered immiscible. Example: oil and water.

Question 11. Differentiate between a saturated and an unsaturated solution with an example.
Answer:

Saturated Solution: A glass of water into which you have added as much sugar as can be dissolved at room temperature is an example of a saturated solution.

Unsaturated Solution: If you add sugar to a glass of water and it completely dissolves, leaving no sugar at the bottom, but you know you could still add more sugar and it would dissolve, then it is an example of an unsaturated solution.

Question 12. Define solute and solvent.
Answer:

Solute: A solute is the substance that is dissolved in a solvent to form a solution. It is present in lesser quantity compared to the solvent.

Solvent: A solvent is the substance in which the solute dissolves to form a homogeneous mixture. It is usually present in greater quantity than the solute.

Question 13. Explain the term "insoluble."
Answer:

Insoluble refers to a substance that has very limited or no ability to dissolve in a particular solvent under certain conditions. For example, sand is insoluble in water.

Question 14. Define a supersaturated solution.
Answer:

A supersaturated solution is a solution that contains more dissolved solute than would normally be possible at a given temperature and pressure. It is achieved by dissolving the solute in hot solvent and then cooling the solution slowly, preventing the excess solute from precipitating out.

Question 15. Explain the term "aqueous solution".
Answer:

An aqueous solution is a solution where water is the solvent. It means that the solute is dissolved in water to form a homogeneous mixture. Aqueous solutions are common in many chemical reactions and biological processes.

Question 16. Differentiate between a true solution and a colloidal solution.
Answer:

True solution: In a true solution, the solute particles are molecular or ionic in size, typically less than 1 nanometer, and they do not scatter light. The particles are uniformly dispersed and do not settle out. Colloidal solution: In a colloidal solution, the dispersed particles are larger than individual molecules but smaller than those in suspensions. These particles scatter light and may settle slowly over time.

Question 17. Provide an example of a gas-liquid solution.
Answer:

Carbon dioxide (CO2) dissolving in water is an example of a gas-liquid solution. When carbon dioxide is bubbled through water, it dissolves to form carbonic acid, resulting in a solution.

Question 18. Explain the term "saturation point" in the context of solubility.
Answer:

Saturation point is the point at which no more solute can dissolve in a solvent under specific conditions of temperature and pressure. At this point, the solution is saturated, and any additional solute added will not dissolve.

Question 19. What is a solution?
Answer:

A solution is a homogeneous mixture composed of two or more substances uniformly dispersed at the molecular or atomic level. It consists of a solvent (the substance in which the solute dissolves) and one or more solutes (substances dissolved in the solvent).

Question 20. How does temperature affect solubility?
Answer:

In general, the solubility of most solid solutes in liquid solvents increases with an increase in temperature. However, for gases in liquid solvents, solubility often decreases with increasing temperature. An example is the increased solubility of sugar in hot water compared to cold water.

Question 21. How does molarity change with dilution?
Answer:

Dilution decreases the molarity of a solution because it increases the volume of the solvent while keeping the amount of solute constant. As a result, the concentration of the solution decreases. For example, if you add water to a 1 M solution of sodium chloride to make it 2 liters instead of 1 liter, the molarity of the solution will become 0.5 M.

Question 22. Differentiate between solute and solvent with examples.
Answer:

Solute: Examples of solutes include salt (NaCl) in saltwater, sugar in water, and carbon dioxide (CO2) in soda.

Solvent: Examples of solvents include water (H2O), which is often referred to as the universal solvent, ethanol in rubbing alcohol, and acetone in nail polish remover.

Question 23. What are the different types of solutions based on the physical state of the solvent and solute?
Answer:

Solutions can be categorized into three main types:

Solid solutions: These are formed when a solid solute is dissolved in a solid solvent. Example: alloys like brass (copper dissolved in zinc).

Liquid solutions: These are formed when a liquid solute is dissolved in a liquid solvent. Example: ethanol dissolved in water to form alcoholic beverages.

Gaseous solutions: These are formed when a gas solute is dissolved in a gas solvent. Example: air, which is a mixture of gases like oxygen, nitrogen, and carbon dioxide.

Question 24. Why is water often called the "universal solvent"?
Answer:

Water is often referred to as the universal solvent because it has the ability to dissolve a wide range of substances due to its polar nature. Its polar molecules are capable of forming hydrogen bonds with other polar molecules, ions, and polar covalent compounds, facilitating the dissolution process. This property makes water essential for many biological and chemical processes.

Question 25. Explain the concept of saturation in a solution.
Answer:

Saturation refers to the condition where a solution contains the maximum amount of solute that can dissolve in a given amount of solvent at a particular temperature and pressure. Any additional solute added will not dissolve and will remain as a separate phase in the solution.

Question 26. How does the nature of the solute and solvent molecules influence solubility?
Answer:

The nature of solute and solvent molecules, including their polarity and intermolecular forces, influences solubility. Generally, polar solutes dissolve better in polar solvents, and nonpolar solutes dissolve better in nonpolar solvents. Additionally, molecules with similar structures or functional groups are more likely to be soluble in each other.

Question 27. Can you provide an example of an aqueous solution?
Answer:

An example of an aqueous solution is saltwater, where salt (solute) is dissolved in water (solvent) to form a homogeneous mixture.

Question 28. Define molarity and explain how it is calculated.
Answer:

Molarity (M) is a concentration unit that expresses the number of moles of solute dissolved in one liter of solution. It is calculated using the formula:

Molarity = Number of moles of solute / Volume of solution in liters

​For example, if 0.5 moles of sodium chloride (NaCl) are dissolved in 1 liter of water, the molarity of the solution is 0.5 M.

Question 29. Define solubility.
Answer:

Solubility is the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature and pressure to form a saturated solution.

Question 30. Explain the concept of solubility in the context of saturated solutions.
Answer:

Solubility refers to the maximum amount of solute that can dissolve in a solvent to form a saturated solution at a particular temperature and pressure. It is expressed in units such as grams of solute per 100 grams of solvent. If more solute is added beyond this limit, it will not dissolve and will result in an unsaturated or supersaturated solution, depending on the conditions.

Question 31. Differentiate between homogeneous and heterogeneous solutions.
Answer:

Homogeneous solution: In a homogeneous solution, the solute is uniformly distributed throughout the solvent at the molecular level, resulting in a single phase. Example: saltwater.

Heterogeneous solution: In a heterogeneous solution, the components are not uniformly distributed, resulting in visible differences or phases. Example: a mixture of oil and water.

Question 32. Differentiate between a solution, a suspension, and a colloid.
Answer:

A solution is a homogeneous mixture where solute particles are evenly distributed and do not settle out. Example: Saltwater (sodium chloride dissolved in water).

Suspension: A suspension is a heterogeneous mixture where solute particles are larger and settle out over time. Example: Muddy water, where soil particles are suspended in water but eventually settle at the bottom.

Colloid: A colloid is a heterogeneous mixture where solute particles are intermediate in size between those in a solution and a suspension. They do not settle out and exhibit the Tyndall effect. Example: Milk, where fat globules are dispersed in water.

Question 33. What factors affect the rate of solvation in a solution?
Answer:

Factors affecting the rate of solvation include:

Temperature: Generally, higher temperatures increase the rate of solvation as it provides more energy for solvent molecules to overcome intermolecular forces and surround the solute particles.

Agitation: Stirring or shaking the solution increases the rate of solvation by bringing fresh solvent into contact with the solute.

Surface area: Smaller solute particles or increased surface area of the solute allow for more contact with the solvent, speeding up the rate of solvation.

Question 34. Explain the term "supercritical solution."
Answer:

A supercritical solution is a state where a substance is heated and pressurized to a temperature and pressure above its critical point, resulting in properties that are intermediate between those of a liquid and a gas. In this state, the substance can dissolve both polar and nonpolar compounds with high efficiency, making it useful in various industrial processes such as extraction and chromatography

Question 35. Provide an example of a saturated solution.
Answer:

An example of a saturated solution is preparing a glass of sweet tea where you dissolve sugar in hot water. Once you reach the maximum amount of sugar that can dissolve in the water at that temperature, further sugar added will not dissolve and will settle at the bottom of the glass.

Question 36. Define a saturated solution.
Answer:

A saturated solution is a solution that contains the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature and pressure. At saturation, any additional solute added will not dissolve and will remain as a separate phase in the solution.

Question 37. Provide an example of each: a solution, a suspension, and a colloid.
Answer:

Solution: Sugar dissolved in water to make a sweetened beverage.

Suspension: Sand mixed with water, where sand particles settle at the bottom over time.

Colloid: Fog, where tiny water droplets suspended in the air scatter light, making the beam visible.

Question 38. Provide an example of a colloidal solution.
Answer:

An example of a colloidal solution is milk, where fat globules are dispersed throughout the water-based solution. Another example is fog, where tiny water droplets are suspended in the air.

Question 39. What is a liquid solution? Provide an example.
Answer:

A liquid solution is formed when a solute is dissolved in a liquid solvent. An example is vinegar, where acetic acid (the solute) is dissolved in water (the solvent) to form a homogeneous mixture.

Question 40. Can you provide an example of the dilution of a solution?
Answer:

Dilution can be demonstrated by adding water to concentrated orange juice. As more water is added, the concentration of the orange juice decreases while the volume of the mixture increases. The taste becomes less intense as the solution becomes more diluted.

Question 41. How does the solubility of a substance in a solvent affect the formation of a solution?
Answer:

The solubility of a substance in a solvent determines the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature and pressure. If the solubility is high, more solute can dissolve, leading to a saturated solution. If the solubility is low, only a small amount of solute can dissolve, resulting in a dilute solution.

Question 42. Calculate the mass percent of a solution if 50 grams of solute are dissolved in 200 grams of solvent.
Answer:

Mass percent = Mass of solute / Mass of solution × 100%

Using the given values:

Mass percent = 50g× 100% / (50g + 200g)

= 50g× 100% / 250

= 20%

Question 43. Define volume percent and provide an example.
Answer:

Volume percent is a percentage concentration unit that expresses the volume of solute present in a solution relative to the total volume of the solution.

Example: If 20 mL of ethanol is dissolved in a total volume of 100 mL of solution, the volume percent of ethanol in the solution would be

20mL × 100% / 100mL

= 20%

Question 44. Explain the concept of percentage concentration.
Answer:

Percentage concentration expresses the amount of solute present in a solution relative to the total amount of solution, typically expressed as a percentage. There are different ways to calculate percentage concentration, such as mass percent, volume percent, and weight/volume percent.

Question 45. What is weight/volume percent?
Answer:

Weight/volume percent is a percentage concentration unit that expresses the mass of solute dissolved in a given volume of solution. It is commonly used in pharmacy to prepare solutions. An example would be a 5% (w/v) solution of glucose, which means 5 grams of glucose are dissolved in 100 mL of solution.

Question 46. Explain how the properties of solutions, suspensions, and colloids affect their applications.
Answer:

Solutions: Solutions are commonly used in various chemical reactions, as solvents for medications, and as beverages. They provide uniform distribution of solute molecules.

Suspensions: Suspensions are used in products like paints, where solid particles remain suspended for an extended period before settling.

Colloids: Colloids find applications in food industry (e.g., emulsions like mayonnaise), pharmaceuticals (e.g., suspensions for drug delivery), and materials science (e.g., nanoparticle dispersions). They exhibit unique optical, mechanical, and chemical properties due to their dispersed phase.

Question 47. Explain the concept of "like dissolves like."
Answer:

“Like dissolves like” is a general rule indicating that substances with similar polarities or chemical structures are more likely to dissolve in each other. Polar solvents tend to dissolve polar solutes, and nonpolar solvents tend to dissolve nonpolar solutes. For example, water (polar) dissolves salt (ionic), while hexane (nonpolar) dissolves oil (nonpolar).

Question 48. Explain the process of dilution of a solution.
Answer:

Dilution is the process of reducing the concentration of a solution by adding more solvent without changing the amount of solute present. It results in a decrease in the number of solute particles per unit volume, leading to a decrease in concentration.

Question 49. Provide an example of a homogeneous solution.
Answer:

An example of a homogeneous solution is a sugar solution where sugar is completely dissolved in water, resulting in a uniform mixture with no visible separation.

Question 50. Can you provide an example of a gaseous solution?
Answer:

An example of a gaseous solution is air, which is composed of various gases such as nitrogen, oxygen, carbon dioxide, and trace amounts of other gases. Each gas in air behaves as a solute, while the overall mixture serves as the solvent.

Question 51. Describe the stability of solutions, suspensions, and colloids over time.
Answer:

Solutions: Solutions are stable and do not separate into distinct phases over time.

Suspensions: Suspensions are unstable and tend to settle out over time due to gravity.

Colloids: Colloids are relatively stable and do not settle out due to the Brownian motion of particles, which prevents aggregation and settling.

Question 52. Explain the Tyndall effect and its significance in distinguishing between solutions, suspensions, and colloids.
Answer:

The Tyndall effect is the scattering of light by colloidal particles when a beam of light passes through a colloidal solution. It is not observed in solutions or suspensions. This effect helps in distinguishing between these types of mixtures, as it indicates the presence of colloidal particles dispersed in the solution.

Question 53. Explain how a supersaturated solution can be formed.
Answer:

A supersaturated solution can be formed by first dissolving a larger amount of solute in a solvent at an elevated temperature, where solubility is higher. Then, the solution is slowly cooled down without allowing the excess solute to precipitate out. This can result in a metastable state where the solution contains more solute than would typically be possible.