Unit 4 Review

Wow we started this unit a long time ago!

Lessons 1 and 2

Lesson one introduces the unit and defines toxins as harmful substances that can harm and enter the body in many ways. Lesson two goes into the chemical equations of these toxins. Equations help scientists predict and track chemical changes.
Practice Problem
3A. A solid and an aqueous solution combine to form an aqueous solution and gas.

Lessons 3-6

Lesson 3 was about physical and chemical changes. A physical change is a change in matter in which a substance changes form but not identity.(Dissolving) A chemical change is a change in matter that results in the formation of a new substance with new properties.  Lesson 4 is about the law of conservation of mass which states that matter can't be created or destroyed during a chemical reaction. And then lesson 5 taught us how to balance equations, when doing so you can only change the coefficient. Lesson six went into further detail about chemical equations and classifying them into 4 major groups:
Combination: A+B => AB
Decomposition: AB => A+B
Single Exchange: A + BC => AC + B
Double Exchange: AB + CD => AC + BD
Practice Problem
3A. NaOH (aq)+ HNO3 (aq) => NaOH3 + H2 (l)

Lessons 7-8

Lesson 7 was about lethal doses, which is an amount of an ingested substance that kills 50% of a test sample of animals. (mg/kg) The smaller the dose the more toxic it is. Then lesson 8 was about percent error. There is a picture of the equation below.

 

 

Lessons 9-11

 

Lesson 9 talks more about moles. The mass of 1 mole is equal to the molar mass. Then on the periodic table the atomic mass is equal to 1 mole of atoms of the element in grams. You use molar mass to convert between moles of atoms and grams of atoms. Lesson 10 put our skills to the test and we had to make sure to remember to label our numbers with units and make sure our units cancel out.  And lesson 11 continued on with this theme so heres some practice problems.

 

Lesson 12-15

In lesson 12 we learned that aspartame is much sweeter than fructose. The smaller the LD50 the more toxic it is. LD50 values are of limited use in determining the long term effects of a substance. Even if you don't reach the actual LD50 there could be very serious long term effects that are not accounted for in the LD50. In lesson 13 we learned that a solute is a substance dissolved in a solution. A solvent is the substance in which a solute dissolves. ( A flute in a vent!) And that molecules in a high concentration area move to areas of lesser concentration. (Molarity) In lesson 4 we put our new found skills to the test.

 



 

 

Lessons 15-19

 

The biggest thing we learned in lesson 15 was that you can use a hydrometer to test the molarity of the substance. In this next lesson we basically used all the knowledge we've gained from throughout the chapter to solve problems. We also did an activity where we had to try and figure out which solutions were which by weighing them and accounting for the molar mass.

In lesson 17 we learned that an indicator is molecular substance that changes color when it comes into contact with an acid or a base.

Acids and bases are corrosive. When pH is 7 it is neutral or pure water. Below 7 is an acid and above 7 is a base. This is a picture of the pH scale.

These pH solutions are classified by their colors you can observe. Acids and bases change the color of indicators.

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Lesson 18 taught us about cabbage juice and its indicator colors. Cabbage Juice: Pink=acidic, Green=basic, Purple=neutral. Substances that add H+ (just one proton) to a solution are acids. Bases are substances that add OH- to a solution. Substances that don't add H+ or OH- to the solution are neutral.

• Arrhenius Definition: An acid is any substance that adds hydrogen ion to solution. A base is any substance that adds hydroxide ion to a solution.
• Brønsted-Lowry Definition- An acid is a proton donor. A base is a proton acceptor.

The products of a reaction is always called a conjugate.

Lesson 19 talked more about the pH scale. The pH scale is a logarithmic scale the describes the concentration of H+ ions. pH is related to H+ by the formula: pH=-log[H+] Water dissociates into H+ and OH- ions. Below is a picture of the pH scale and examples of substances that fit into each pH level.

 

 

Practice Problems

7. The NaBr would weigh the most because it has more solute than NaOH. The KCl weighs half as much as the other two because, 500 mL is less than 1 L or 1000 mL.

1. A base is a substance that adds a OH- ion to a substance and an acid is a substance that adds a H+ ion to a substance



Lessons 20-25

Lesson 20 was about dilution. When you dilute something you make it either less basic or less acidic. 7 is the neutral number in the pH scale and by diluting a solution you can approach 7 but you can't turn an acid into a base and visa versa by dilution. We also learned that between each number on the pH scale there is a 10 fold. Then we learned about neutralization, which is when a strong base and a strong acid react and form ionic salt and water. We also learned that when two compounds have the same volumes and the same molarity they have the same number of moles. When this happens its neutral. Then in lesson 22 we learned that titration is the neutralization process between a strong acid and base. When a strong acid is mixed with a weak base there isn't enough OH- ions to neutralize all of the H+ ions so the solution will not be neutral. It will however, be closer to 7 than either starting solution. In lesson 23 we learned about precipitates, which are solids that are produced in a chemical reaction between two solutions. Sometimes The mixing of two ionic solutions results in the formation of a solid. The degree to which a compound dissolves in water is called it's solubility and precipitation is not limited to solids. Lesson 24 was all about molar ratios. A mole ratio is a ratio given by the coefficients in a balanced equation.
Lesson 25 basically continued to break down the mole tunnel and mole ratios into 3 steps. The mole tunnel is just the way you set up your equation to solve mole ratio problems. First, convert grams to moles. Next, find the molar ratio, and last convert grams into moles.  ANd finally lesson 26 was abput percent yield which is The equation for percent yield is the actual amount, divided by the theoretical amount and multiplied by 100.

Practice Problems

Disappearing Spoon - Chapter 15-17

Chapter 15, opened with a story about William Crookes. In order to take care of his extremely large family,(large group growing up and eventually had 10 children of his own, that seems like entirely too many if you ask me!) he wrote a book on diamonds and edited a science journal. Then the story moved to his brother and his life. He was known for spiritualism, and pioneering the study of selenium. When the brother died the chapter moved into pathological science is. The book then moves into a story about the Pons and Fleischmann. This was a family known for cheating. They created two protons and two neutrons of hydrogen gas. Instantaneously the two became famous and scientists all over had the idea of cold fusion.  As in any large discovery, many skeptics remained. It turns out their skepticism proved worthy. It was discovered that the family had overlooked many issues and had measured incorrectly. A protest against the family then follwed. The end of the chapter was about X-rays. Rontgen discovered the basics of X-rays, and later Henry Moseley executed these basic X-ray set ups.
Chapter 16 talked about tin in the beginning. Tin can turn carbon from graphite into diamonds, it becomes protean at 56 degrees F. Then it talked about temperatures and solids. Lastly, it talked about light and the first laser light. This idea was quickly thrown out after being deemed impossible by Niel Boher and Von Neumann. In chapter 17, a man named Donald Glaser, who invented the bubble chamber. He used a various liquids like as beer, hydrogen, and calcium for his experiments. Calcium bubbles have shaped economics and empires. Over time, bubble science became a respectable field because of the work of Ernest Rutherford and Lord Kelvin. Rutherford was even able to discover a new element. He won th Nobel Prize in 1908 and that's where he announced the alpha-helium connection. Kelvin's discoveries inspired military work. The chapter ended with the engineering of bubbles. Bubbles have interested physicists to engage in alternative energy. I wasn't the largest fan of these chapters, the bubble thing was kinda cool I guess. But I can't complain, State Champs 2012!

Lessons 25 and 26

Lesson 25

Lesson 25 basically continued to break down the mole tunnel and mole ratios into 3 steps. The mole tunnel is just the way you set up your equation to solve mole ratio problems. First, convert grams to moles. Next, find the molar ratio, and last convert grams into moles.

 

Practice Problem

 

 

Lesson 26

Lesson 26 talked about limiting reactants. When comparing reactants to find the limiting reactant, compare moles not grams. If you have two products it doesn't matter which one you us, just turn all reactants into the same products. Then we talked about percent yield. The equation for percent yield is the actual amount, divided by the theoretical amount and multiplied by 100. The actual number is the number that you would get in a a perfect scenario. The theoretical number account for what you would probably be true to things like water droplets in the beaker and gas escaping. The percent yield can be in moles or grams.

Practice Problem

 

 

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Lessons 23 and 24

Lesson 23

In this lesson we learned about precipitates, which are solids that are produced in a chemical reaction between two solutions. Sometimes The mixing of two ionic solutions results in the formation of a solid. The degree to which a compound dissolves in water is called it's solubility and precipitation is not limited to solids.

In this chart S means soluble (liquid), N means not soluble (solid)

 

Lesson 24

This lesson was all about molar ratios. A mole ratio is a ratio given by the coefficients in a balanced equation, showing how many units of each substance must combine to make the maximum amount of product. Now when these reactants aren't combined in their perfect mole ratio, one reactant runs out (called the limiting reactant) and one is left over, which is called the excess reactant. When you compare things in a balanced equation you must look at the moles.

Practice Problem

 

 

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Disappearing Spoon-Chapters 13 and 14

Chapter thirteen's theme was money and how elements relate to it. We all know the story of Midas, the greedy king whose touch turned things into gold. Naturally humans wanted to replicate this insane power so some scientists looked into it and assumed that the "touch" was just zinc in the soil. So they loaded a furnace up with ores; melted them, molded them, and let them cool. It hardened into gold. That's when the city of gold stories came into light and then the gold rushes. A man named Hannan found a place where gold was everywhere. Boom. GOld rush, panic and chaos in an attmept to get rich. This only escalated when it was discovered that gold can be formed inside rocks when it's mixed with tellurium. Now any rock anywhere had a chance of containg gold. After another story or two the topic changes to light,electrons and aluminum. Charles Hall ran an electric current from homemade batteries through a liquid and dissolved aluminum, creating an energry source that was fast and simple. This idea made him quite famous and the chapter ending with talks of the different ways to spell aluminum.
Chapter Fourteen talked about colors of elements on the periodic table. Johann Wolfgang von Goethe challenged Isaac Newton's theory of how colors work in poem which made him scientific credibility limited. And as the write he was, he wrote a novel about marriages are like chemical reactions, which was moderately hilarious sounding. It talks about AB + CD —> AD + BC in that if one couple comes in contact with another couple, the couples will split up and become in a relationship with a person from the other relationship. The lesson I got here was to never double date and to assume everyone is a backstabber. When Kenneth Parker tried to get his family business to make pens is really when the asthetics really came into play. Through trial and error the Parker 51 pen came out in 1941. The pen basically dissolved fibers of the paper which means it would dry faster. I found that kinda odd.  The tip was ruthenium instead of gold, which made it way cooler than all other pens as well. I felt like 14 was a little obsessed with their pen idea but It was not my least favorite chapter so I guess that's a bonus. Five chapters left!