Bio Exam Prep

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CHAPTER 11- MEASURING SOLUBILILTY

Solubility- The maximum amount of that substance that can be dissolved in a given quantity of solvent at a certain temperature.

Saturated Solution- Solution in which no more solute can be dissolved in.

Supersaturated Solution- A solution that contains more solute than a saturated solution. (Any point above its solubility curve)

Crystallisation- The process of ions coming out of a saturated solution as the solubility decreases (when temperature decreases). It is accompanied by the release of heat.

Solubility of Gases

- Gases are much less soluble in water than solid substances.

- It depends of the temperature of the liquid and the pressure of the gas.

- The higher the temperature the lower the solubility of the gas.

- Solubility increases with increasing pressure

Concentration- the ratio of solute to solvent or the amount of solute in a given amount of solvent.

Concentrated solution-A solution with a high solute to solvent ratio

Dilute solution-A solution with a low solute to solvent ratio.

Molar Concentration (molL-1) or Molar Volume (M)-The number of moles per Litre of a solution is known as the molar concentration.

Concentration (molL-1) = mol/ volume in (L)

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Unit conversion:

Dilution- The process of adding more solvent to a solution.

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Chapter 12- Water: Removing dissolved solutes

Precipitation Reactions

Precipitate- The solid that forms when two substances react.

Ionic Equations

- When ionic substances dissolve in water, they dissociate into ions.

- It is the free ions that react to form a precipitate so the equation should be expressed in terms of ions.

- There will be a pair of ions that do not change in the reaction these are called Spectator ions and are removed from the equation.

Chapter 13- Introducing Acids and Bases

Acids

- Tend to be corrosive

- Taste sour

- React with bases

- Have a low pH

- Turn Blue Litmus red

Eg. HCl, H2SO4, HNO3.

Bases

- An alkali is an aqueous solution of a soluble base.

- Have a slippery feel

- Are caustic

- React with acids

- Have a high pH

- Turn Red Litmus Blue

- Eg. NaOH, NH3, Ca(OH)2

Acids and bases neutralise each other.

Reactions involving Acids

1. Acid + reactive metal= salt + hydrogen

2. Acid + metal Hydroxide= salt + water

3. Acid + metal Oxide= salt + water

4. Acid + metal Carbonate= salt + water + Carbon Dioxide

5. Acid + metal hydrogen Carbonate= salt + water + Carbon Dioxide.

Chapter 14- Acids and Bases

BrØnsted-Lowry Theory of Acids and Bases- acids are proton donors

-bases are proton acceptors[pic 36]

Acid- base conjugate pairs-Two species which differ by a proton. That is, formed by the loss or gain of a single proton. In this case, HCl and Cl- are acid base conjugate pairs because the Cl- has now become a base which needs to accept a proton.

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Amphiprotic substances-substances that can act as either an acid or base.

- It depends whether the solution present is a stronger acid (then substance will act as an acid) or a stronger base (then substance will act as a base).

- Eg. H2O and HCO3-

ACID BASE STRENGTH

- The strength of an acid is in its ability to donate protons (the more giving the stronger)

- The strength of an acid is in its ability to accept protons (the more accepting the stronger)

Strong acid- Acids that ionise completely in solution. They donate protons more easily.

Weak acid- Acids that do not completely ionise in a solution. Shown by reversible arrows.

Strong base- accepts protons easily.

Weak base- Bases that do no completely react with acid in solution; there is some original

substance left and is shown through reversible arrows.

Polyprotic Acids- Acids capable of donating more than one proton from each molecule.

- Monoprotic- Acids that donate one proton in a reaction

- Diprotic- Acids that can donate 2 protons in 2 reactions

- Triptotic- Acids that can donate 3 protons in 3 reactions

Strength vs. Concentration

- Concentration- the amount of given acid or base dissolved in a given solution

ACIDIC,