D.S. Chapter 15

An Element of Madness

William Crookes came from a large family and was in England's premier scientific club but when his brother Philip died he turned to the supernatural to try to find comfort. Even after his earlier findings in the study of selenium and his discovery of thallium and then later giving the first suggestion of isotopes, his fellow scientists called him crazy and attacked his character. Stanley Pons and Martin Fleischmann let their whimsical sides get the better of them when they ran a current through water with hydrogen that have an extra neutron and a palladium electrode. Palladium takes in 900 times its volume of hydrogen and when it took in the heavy hydrogen temperatures spiked erratically so that the duo thought they had discovered cold fusion available at room temperature. Skeptics rooted out their claims by finding the two had overlooked procedures and their findings were dismissed within 40 days. But the spirit of cold fusion and finding cheap clean energy didn't die even through countless counter experiments and results. On the opposite end of the spectrum, Wilhelm Röntgen actually tried to prove himself wrong when his results made him think he was going mad. When playing with a beam of electrons in a Crookes tube, he thought he was hallucinating when he saw a barium plate light up even though the tube was darkened. Playing with objects, he came to the conclusion he'd gone mad when he was able to see through things, even his own hand. He had discovered x-rays but refused to be revolutionary so he experimented till he couldn't prove himself wrong and he backed his findings up to every other scientist that was cruel to his new idea.

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Unit 4 lesson 23 & 24

Lesson 23 - Precipitation Reactions

Precipitate- a solid produced in a chemical reaction between two solutions

Substances with low solubility tend to form precipitates in aqueous solutions

Most reactions involve double exchange reactions with ionic compounds where the cations exchange anions.

Lesson 24 - Mole Ratios
Coefficients in chemical equations refer to the number of units like molecules, moles, or ions that are combining.

Mole ratio- ratio represented by the coefficients in a chemical equation showing how many units of each substance must combine to make the maximum amount of product.

Reactants combined in a imperfect mole ratio run out of one while leaving behind more of the other:

        - limiting reactant - runs out

        - excess reactant - leaves more behind

When comparing the two reactants, compare the moles to find out which is limiting and which is excess. Don't use the coefficients.

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Disappearing Spoon Chapters 13

13- Elements as Money

Elements and money have always been intermingled, especially metallic elements. From Midas, who turned everything he touched into "gold", which was really just gold-hued brass that shined brighter than the Greeks' bronzes and so grew into myths of magic, to the Irish Patrick Hannan who was tricked into starting the fool's fool's gold rush in 1893 only to discover that the miners were discarding the actually valuable tellurium which is one of the very few elements that combines with gold. The miners soon tore apart the town they had built to get at the telluride-infused bricks. In 540 BC was the creation of a real currency system by the Lydian king Croesus who separated electrum into silver and gold coins. But a real currency system brings those who want to create their own money through counterfeiting. Isaac Newton even played a role in bringing in the wrongdoers in the 1600s. After that came paper currency with a whole new level of counterfeiting. The government needed to rival it so they used europium dyes which can emit fluorescent colors but with a receiver that absorbs the light causing europium electrons to stir and jump to higher energy levels emitting the light but dampened. This allows officials to pick out the real money under certain lights thus combatting the counterfeiters. Metals markets are always some of the most stable and long term sources of wealth. In 1886 Charles Hall discovered a way to separate aluminium (the most valuable substance at that time) from oxygen by running an electrical current through a liquid with dissolved aluminium which no one previously had figured out to do. He created an aluminum empire and made millions on the metal we use so commonly today.

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Unit 4 Lessons 21 & 22

Neutralization Reactions

• A neutralization reaction where adding acids and bases together neutralizes the solution producing an ionic salt compound and water
• Can be described as a double exchange where 2 compounds exchange cations

Ex: H2SO4 + Mg(OH)2 —> 2H2O + MgSO4
Practice Problems
7. C & D
8. B

Titration

    - procedure where a neutralization reaction is monitored with an indicator to get the unknown concentration
           - equivalence point is reached in a titration between a strong acid and a strong base , # of moles of H+ ions equals # of moles of OH- ions
Practice Problems
3) 1L of NaOH
5) a) acidic b) neutral c) basic

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Unit 4 Lesson 20

Dilution

This means that 8 is ten times more basic than 7 is one hundred times more acidic than 7.

You can add water to a solution to dilute it.

• In an acidic solution, adding water increases it's pH closer and closer to 7
• In a basic solution, adding water decreases the pH closer and closer to 7
• You can't reach a pH of 7 by simply diluting the solution with water and so you can't change an acid into a base or vice versa.

Practice Problems

5) because it was diluted so the pH decreased

7) a) .075 mol b) .068 M c) pH 1.17

 

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Unit 4 Lesson 19

[ H+] and pH

Acidity is determined by the concentration or Molarity of H+ ions n moles per liter. This concentration is symbolized by [H+].

The greater the concentration of H+ ions the lower the pH and it is more acidic.

The hydrogen ion concentration is directly related to the pH of the solution.

The pH number is equal to the exponent just without the negative. This is only true in scientific notation when the coefficient is 1.0.

pH is connected to [H+] through the logarithmic formula pH = -log[H+]

Bases' pH can also be determined because bases contain H+ concentrations. The H+ concentration in scientific notation and the exponent subtracted from 14 is the concentration of OH- ions.

Ex: water - [OH-] is 1.0 X 10^-7 and [H+] is 1.0 X 10^-7 because 7+7=14

Formula: [H+][OH-]= 1 X 10^-14

Practice Problems

3. a) pH 4 b) pH 12 c) pH 6

4. a) pH 2.85 b) pH 13.38 c) pH 7.22 d) pH .82

 

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Unit 4 Lesson 18

Acid-Base Theories

Acids

• Made up of main group nonmetals like carbon, oxygen, fluorine, and chlorine
• All have hydrogen
• Break apart to form one H+ and an anion

Bases

• Contain metal atoms and an hydroxide ion, OH-
• Except for hydroxides, the name isn't helpful to identifying them as bases

Changing definitions of acids and bases:

• Arrhenius definition- an acid is any substance that adds a hydrogen ion to a solution. A base is any substance that adds a hydroxide ion to a solution.
• Bronsted-Lowry definition- an acid is a proton donor and a base is a proton acceptor

Acids add H+ (one proton) to the solution

Bases add OH- to the solution

Strong Acids and Bases- dissociate completely in a solution to form only ions. They are good conductors of electricity.

Weak Acids and Bases- only partially dissociate in a solution. Less corrosive

Practice Problems
4. a) acid b) acid c) base d) acid e) acid f) acid g) acid h) base
6. a) 20 OH- ions

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