Oceans Flashcards
How do you know if a solute will dissolve in a solvent?
A solute will dissolve if the energy required to break the bonds in the solute and solvent is less than the energy released when new bonds are formed between them.
Why do substances not dissolve in a solvent?
Substances do not dissolve if the bonds that need to be broken are stronger than those that are formed when the solute dissolves.
What is the general rule for the dissolution of ionic substances?
Most ionic substances dissolve in polar solvents because ion-dipole forces are strong enough to pull the ions away from the ionic lattice.
What is characteristic of non-polar solvents?
Non-polar solvents typically dissolve covalent substances because they have weak intermolecular forces.
What are hydrated ions?
Hydrated ions are ions surrounded by water molecules when dissolved in water. If dissolved in a different solvent, the process is called solvation.
What is standard lattice enthalpy?
Standard lattice enthalpy is the enthalpy change when 1 mole of an ionic lattice is formed from its gaseous ions under standard conditions.
What is the sign and significance of lattice enthalpy?
Lattice enthalpy is always negative because energy is released when bonds are formed. A more negative lattice enthalpy indicates stronger ionic bonds.
What happens during the enthalpy changes when dissolving ionic compounds?
Breaking the bonds between ions is endothermic, while forming bonds between water and ions is exothermic, and the overall enthalpy change is the net result of these processes.
What is the enthalpy change of solution?
The enthalpy change of solution is the heat change when one mole of a compound dissolves in water under standard conditions.
How do you measure the enthalpy change of solution?
The enthalpy change of solution can be measured using calorimetry, typically in a polystyrene beaker with a lid, measuring the change in temperature.
What is charge density?
Charge density is the ratio of charge to the radius of an ion. Higher charge density means the ion has a stronger attraction to opposite charges.
How does charge density affect lattice enthalpy?
A higher charge density leads to stronger attraction between ions, which results in more exothermic lattice enthalpy.
How does charge density affect enthalpy of hydration?
Higher charge density makes ions more attractive to water molecules.
What is entropy?
Entropy is the measure of disorder or the number of ways particles can be arranged. A system tends to increase its entropy to become more energetically stable.
What factors affect entropy?
Entropy is affected by:
* The state of the substance (gas has the highest entropy)
* The amount of energy a substance has
* The number of particles present (more particles = higher entropy)
How do you calculate entropy change?
The entropy change of the system is calculated by subtracting the entropy of the reactants from the entropy of the products.
How do you calculate total entropy change in a reaction?
Total entropy change = Entropy change of the system + Entropy change of the surroundings.
What conditions make a reaction feasible?
For a reaction to be feasible, the total entropy change (system + surroundings) must be positive or zero.
What is solubility?
Solubility is how much of a solute can dissolve in a solvent at a given temperature, forming a saturated solution.
What is Ksp (Solubility Product)?
Ksp is the solubility product constant, representing the equilibrium between a sparingly soluble solid and its dissolved ions in a saturated solution.
What are Bronsted-Lowry acids?
Bronsted-Lowry acids are proton donors. They release H+ ions when they dissociate in solution.
What are Bronsted-Lowry bases?
Bronsted-Lowry bases are proton acceptors. They gain H+ ions when dissolved in solution.
What is the difference between strong and weak acids?
Strong acids fully dissociate in water, while weak acids only partially dissociate.
What is the difference between strong and weak bases?
Strong bases completely ionize in water, while weak bases only slightly ionize.
What are conjugate acid-base pairs?
A conjugate acid-base pair consists of two species that differ by one proton (H+).
What is a neutral solution?
A neutral solution is one where the concentration of H+ ions equals the concentration of OH- ions, resulting in a pH of 7.
How do you calculate pH?
pH is calculated using the formula: pH = -log[H+].
What does Kw represent in water?
Kw is the ionic product constant for water, equal to 1×10−14 at standard conditions.
How do you use Kw to find the concentration of H+ ions?
You can rearrange the equation Kw = [H+][OH−] to find the concentration of H+ ions in pure water.
What is Ka?
Ka is the acid dissociation constant, which measures the degree to which a weak acid dissociates in water.
What is the significance of pKa?
pKa is the negative logarithm of Ka. A smaller pKa indicates a stronger acid.
What are buffers?
Buffers are solutions that resist changes in pH when small amounts of acid or base are added.
What are acidic buffers?
Acidic buffers have a pH less than 7 and are typically made by mixing a weak acid with its conjugate base.
What is the greenhouse effect?
The greenhouse effect occurs when the Earth absorbs UV radiation from the sun, which is then re-emitted as infrared radiation.
How do greenhouse gases transfer energy?
Greenhouse gases absorb infrared radiation, causing the molecules to vibrate, which increases the temperature.
Which gases contribute to the greenhouse effect?
Water vapor, CO2, and methane are key greenhouse gases that absorb infrared radiation.
