Understanding Solutions: Solutes, Solvents, and Types

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Questions and Answers

How does the polarity of two substances influence their ability to form a solution?

For two substances to form a solution, they must have the same nature in terms of polarity.

What are the three steps involved in the formation of a liquid solution?

Overcoming the intermolecular forces in the solvent to give room for the solute. 2. Separating the solute into its individual components. 3. Allowing the solute and solvent to interact to form the solution.

Explain the meaning of a positive enthalpy of solution and its relation to endothermic and exothermic processes.

A positive enthalpy of solution signifies an endothermic process, where heat is absorbed from the surroundings. A negative enthalpy indicates an exothermic process, where heat is released.

How does the energy released when new bonds form compare to the energy used when bonds are broken in an exothermic process?

In an exothermic process, more energy is released when new bonds form than is used when bonds are broken. Signup and view all the answers

How is concentration defined in the context of solutions?

Concentration is a measure of the amount of solute in a given amount of solvent or solution. Signup and view all the answers

A saline solution has a mass of 420 g and contains 45.5 g of NaCl. Find the mass percent concentration of the solution.

10.83% Signup and view all the answers

Wine contains 13% alcohol by volume. Calculate the volume (in mL) of alcohol in 400 mL of the wine.

52 mL Signup and view all the answers

A solution of 200 mL contains 40 g of solute. Find the concentration in percent by mass/volume.

20% Signup and view all the answers

A 75 mL solution is 15% by mass-volume. How many grams of solute are in the solution?

11.25 g Signup and view all the answers

What distinguishes a solution from other types of mixtures?

Solutions are homogeneous mixtures where the solute is evenly distributed throughout the solvent at a molecular level. Signup and view all the answers

Explain how temperature influences the solubility of solids in liquids, and why this effect is important in the creation of supersaturated solutions.

Increasing the temperature often increases the solubility of a solid in a liquid. This allows more solute to dissolve than would at room temperature, setting the stage for creating a supersaturated solution upon slow cooling. Signup and view all the answers

Describe the difference between a 'concentrated' and a 'saturated' solution. Can a concentrated solution also be unsaturated?

A concentrated solution contains a large amount of solute relative to the solvent, while a saturated solution contains the maximum amount of solute that can dissolve in the solvent at a given temperature. A concentrated solution can indeed be unsaturated if it contains a high amount of solute but is still capable of dissolving more. Signup and view all the answers

Describe how you could experimentally determine if a sugar solution is unsaturated, saturated, or supersaturated without knowing the exact solubility of sugar in water.

Add a small amount of sugar crystals to the solution. If the crystals dissolve, the solution is unsaturated. If the crystals don't dissolve, the solution is saturated. If adding the crystals causes more sugar to precipitate out of the solution, it is supersaturated. Signup and view all the answers

Why is it important to consider the 'nature' of substances (polarity) when predicting whether they will form a solution?

Substances with similar polarities tend to be more miscible due to their ability to form favorable intermolecular interactions (e.g., "like dissolves like"). This is related to the energy of solution. Signup and view all the answers

Consider the dissolution of an ionic compound in water. Describe the roles of both enthalpy and entropy in determining whether the dissolution process will be spontaneous.

A spontaneous dissolution requires consideration of both enthalpy ($\Delta H$) and entropy ($\Delta S$). A negative $\Delta H$ (exothermic) favors spontaneity, and a positive $\Delta S$ (increased disorder) also favors spontaneity. The overall spontaneity is determined by the Gibbs free energy change ($\Delta G = \Delta H - T\Delta S$). Signup and view all the answers

If the enthalpy of solution is a large positive value, will the dissolution of a solute in a solvent occur? Explain what must also be true for the process to occur.

If the enthalpy of solution is a large positive value, the dissolution process will likely not occur unless the entropy change is also large and positive, such that the overall Gibbs free energy change ($\Delta G$) is negative. Signup and view all the answers

What happens to the vapor pressure of a solvent when a solute is added to form a solution and why?

The vapor pressure decreases because the solute particles occupy some of the surface area, thus decreasing the number of solvent molecules that can escape into the vapor phase. Signup and view all the answers

Why do ionic compounds typically dissolve better in polar solvents than in nonpolar solvents?

Polar solvents can effectively solvate the ions through ion-dipole interactions, compensating for the energy required to break the ionic lattice. Nonpolar solvents lack this ability. Signup and view all the answers

Explain why 'like dissolves like' using the terms intermolecular forces, solute, and solvent.

"Like dissolves like" means that a solute will dissolve in a solvent if they have similar intermolecular forces. Solvents can better interact and mix with solutes when the attractive forces between the solute and solvent are comparable to the forces within the solute and solvent themselves. Signup and view all the answers

How does pressure affect the solubility of gases in liquids? Explain using the concept of equilibrium.

Increasing the partial pressure of a gas above a liquid increases its solubility in the liquid. The increased pressure drives more gas molecules into the liquid phase until equilibrium is re-established with a higher concentration of dissolved gas. Signup and view all the answers

How can a gas be dissolved into a liquid?

A gas can be dissolved into a liquid by decreasing temperature or increasing the pressure. Signup and view all the answers

Does the quantity of the solute determine if a solution is saturated, unsaturated, or supersaturated?

A solution can be classified as unsaturated, saturated, or supersaturated depending on the quantity of solute present in it. Signup and view all the answers

What does an unsaturated solution contain?

Unsaturated Solution contains less solute than solvent's capacity to dissolve. This means that the solvent can still dissolve more solute. Signup and view all the answers

What happens if you disturb a supersaturated solution and how does it affect the solute?

If you disturb it (like by adding a small crystal of sugar), the extra sugar will suddenly crystallize out of the solution. Signup and view all the answers

What are solutions in chemistry?

Solutions are mixtures of two or more substances distributed throughout a single phase. Signup and view all the answers

What two components make up a solution?

A solution consists of a solute and a solvent. Signup and view all the answers

What is solute in a solution?

The Solute is the substance dissolved in a solution and is usually present in smaller amount Signup and view all the answers

What is the formula to calculate percent by mass?

Percent by Mass= $\frac{Mass \space of \space Solute}{Mass \space of \space Solution} \times 100$ Signup and view all the answers

What is the formula to calculate percent by volume?

Percent by Volume= $\frac{Volume \space of \space Solute}{Volume \space of \space Solution} \times 100$ Signup and view all the answers

What is the formula to calculate percent by mass and volume?

Percent by Mass – Volume = $\frac{mass \space of \space solute \space in \space grams}{volume \space of \space solution \space in \space mL} \times 100$ Signup and view all the answers

How does the exothermic phenomenon occur?

The process is exothermic, if more energy is released when new bonds form than is used when bonds are broken. Signup and view all the answers

Define enthalpy.

Enthalpy is the total heat of the system. Signup and view all the answers

What is a solution when the solute is a gas and the solvent is a solid?

Hydrogen in Palladium Signup and view all the answers

What is a solution when the solute is a solid and the solvent is a liquid?

Salt in water Signup and view all the answers

What is a solution when both the solute and solvent are gases?

Oxygen in Nitrogen Signup and view all the answers

What type of solution results in crystals forming and is considered unstable?

A supersaturated solution. Signup and view all the answers

If a solid solute is added to a liquid solvent and no more solute dissolves, what type of solution is this?

Saturated solution Signup and view all the answers

What type of process is indicated when a positive enthalpy of solution is present?

Endothermic Signup and view all the answers

Flashcards

Solutions

Mixtures of two or more substances distributed throughout a single phase with uniform composition and properties.

Solute

The substance dissolved in a solution, typically present in a smaller amount.