Solutions and Acid/Base Chemistry

Solvent

• Retain s its phase (if different from the solute)

• Usually present in a larger amount than solute

Solute

• Dissolves in slvent

• Changes phases (aq vs l)

• Present in less amounts

Why does somethings dissolve

Solute must be capable of being attracted to the solvent.

• Like dissoves like

  • Polar substance dissolve in polar solvent

  • Non-polar substances dissolve in non-polar solvents

  • Size is a factor (small molecules dissolved better than large ones)

Ionic solubility and Lattice Enthalpy

Inoic solids with high lattice enthalpies tend to be less oluble in H₂O

Electrolytes

When ionic compounds dissociate in water and when they’re present the solution can conduct electricty

Strong electrolytes

Conduct current efficently

• NaCL and HNO₃

Weak electrolytes

Conduct only a small current due to a small amount of ions present

• Vinegar (molecular) and tap water (molecular)

Non- electrolytes

No current flows, only molecules present

• Pure water, sugar solution

Solubility and temperatures

• Solids have higher solubility at higherr temperatures

• Doesn’t affect liquid-liquid solubility

• Gas solubility decreases at higher temperatures

Pressure and gas solubility

• Solubility of gases is directly proportional to the peressure the gas above the liquid.

• Increase partial pressure of CO₂ in the atmosphere leads to more CO₂dissolving in oceans

  • Leads to the formation of H₂CO₃ and lowers pH harming wild life

Soap

Molecules in soap have polar and non-polar ends which makes then capable of attracting the non-polar fat r grease and dissolving into water by surronding it

How to dissolve something quickly

• Temperature: Higher temperature means greater kinetic energy so there’s more colllisions between solute and solvent

• Agitation: More collisions with solute and fresh solvent

• Particle size: Incrases the surface are for dissolution by grind or crushing the solute into powder

Saturated

A solution which contains the maximum amount of solute.

• When additional solute is added, the solution can become supersaturated or have a precipitate present

Unsaturated

Solution that contains less than the maximum amount of solute

Reactions in solutions

• Dissociated ions float freely in solutions

• Some combinations can result in a precipitate. Those ions are the only ones reacting

  • Those that don’t stay free-floating and are called spectator ions

Acids

• H⁺ ions in solution gives the acidic propeties

• Formed by placing a molecular compound in water. Ionizes and forms a new aqueous product, which yield the acidic properties

Bases

• recognized by the OH^- in them

  • Its what gives them their basic properties when dissolved in water

Arhhenius definition

An Acid reacts with water to increase the hydronium ion concentration

A base dissolved in water to increase the hydroxide concetrations

Bronstead- Lowry concept

A BL acid donates a proton to water and a BL base accept a proton from water

Conjugate pairs

Where a species behaves as an acid, the product formed is capable of acting as a base

• Conjugate base

The strength helps determine if the acid is strong or weak.

• Same works for base: It’s called the conjugate acid

Amphiprotic

A compund that can act as a proton acceptor in one reaction and as a proton donot in another

Strong acids

• Ionize completely in water

• Halogen- containing

• Conjugates cant ever do the reverse reaction.

Classifying acids

• The more concentratted acid is, the more dangerour is it is

• They can either be strong or weak and it depends on the amount of H⁺ ions are in the solution

Weak acids

• Show two arrows

• All the rest of the acids are weak.

• Small portion of acid ionizes and the rest is dissolved molecularacid

Weak bases

Organic molecules that contain nitrogen atoms with lone piars of electrons that can act like a BL bases and take a proton from water

It doesnt happen completely and these compounds are weak bases

Reactions of Acids and Bases

• Acids and bases neutralize eachother, forming water and an ionic compound

• Acids can be synthesized by adding a non-metal oxide to water

• Acids react with metals to produce hydrogen gase and a new ionic compound

• Acids react with carbonate compounds to produce an inoic compound, carbon dioxide, and water

• Acids reach with hydrogen carbonate compounds to produce an ionic compound, carbon dioxide and water

• Base may be synthesized by the reaction of a metal oxude and water

• When placing a metal oxide in an acid, it will react with water first, the neutralization will happen base on solubility

Lewis acid: electrophile

An electron pair acceptor

Lewis base: nucleophile

Electron pair donator

Indicators

• weak acids

• When dissolved in water, they will come to equilibrium with its conjugate base

Tirant

Solution of known concetration

Analyte

Substance being analyzed

standardize

determining the concetrationg of a solution base on a mass of a substance

Equivalence point

Enough titrant added to react exactly with the analyte

End point

the indicator changes color so you can tell the equivalence point

Titration

When we can use pH indicators to let us know when this has happened

• If your want to know the molarity of an acid

Titration lab technique

• Place a known volume of the acid in the flask

• Add a pH indicator

• Add base of a known concetration until the end point has been reached

• Record the volume of base added

• Perform stoichiometric calc to determine concetration of H⁺ in the acid

Burette

• Measure the amount of titrant added

• Clean like a pipette, rinse with water, then with titrant. Run titrant through stocock and into waste. Shake to remove air bubbles

Volumetric glassware

• Most accurate, more desriable for making solutions

Solutions to solid

• Find the mass of solute you require

• Mass out solid into a beaker or onto a weighing paper

• Dissolve the solid into approx half of the total volume of solution in a beaker

• Trans the contents of the beaker to a volumetric flask

• Rinse the beaker and stirring rod, and transfer that liquid to the volumteric flash

• Carefully add water until the meniscus

Water and being a universal solvent

Its a polar molecule that allows it to dissolve in any other liquid

Solutions from stock solutions

• Find the volume of liquid required to make your solution

• Measure that volume using a pipette. Measure meniscus properly

• Empty the pipette into a beaker. Add approximatedly half of the the final volume of solution and stir to mix

• Rinse the beaker and stirring rod, and transer that liquid to the volumetric flask

• Carefully add water until the meniscus reaches the etched line

• Stopper, invery to mix