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Living By Chemistry

Living By Chemistry. Unit 4: TOXINS Stoichiometry, Solution Chemistry, and Acids and Bases. In this unit you will learn:. how toxins are defined how chemists determine toxicity the mechanisms by which toxic substances act in our bodies and what this has to do with chemical reactions.

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Living By Chemistry

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  1. Living By Chemistry Unit 4: TOXINS Stoichiometry, Solution Chemistry, and Acids and Bases

  2. In this unit you will learn: • how toxins are defined • how chemists determine toxicity • the mechanisms by which toxic substances act in our bodies and what this has to do with chemical reactions

  3. Section I: Toxic Changes • Lesson 1 Toxic Reactions • Lesson 2 Making Predictions • Lesson 3 Spare Change • Lesson 4 Some Things Never Change • Lesson 5 Atom Inventory • Lesson 6 What’sYour Reaction?

  4. Lesson 1: Toxic Reactions • Chemical Equations

  5. Day 1 ChemCatalyst 1. What toxins have you encountered in your life? 2. How can toxins enter the body? 3. How can toxins harm you?

  6. Key Question • How do chemists keep track of changes in matter?

  7. You will be able to: • complete basic translations of chemical equations • give a basic definition of a toxin

  8. Prepare for the Demonstration • Work in pairs.

  9. Prepare for the Demonstration (cont.) • Hydrochloric acid is corrosive. Wear safety goggles. Have extra baking soda on hand for spills. HCl(aq) + NaHCO3(aq)  NaCl(aq) + H2O(l) + CO2(g)

  10. Discussion Notes • HCl(aq) + NaHCO3(aq)  NaCl(aq) + H2O(l) + CO2(g) The chemical equation represents a change in matter using symbols and formulas.

  11. Discussion Notes (cont.) • Toxins can enter the body in a limited number of ways. • Toxins often react with water in the human body. • Toxins may be molecular, ionic, or metallic substances.

  12. Wrap Up • How do chemists keep track of changes in matter? • Chemical equations help chemists keep track of the substances involved in chemical changes. • Chemical equations use chemical formulas to indicate the reactants and products of chemical changes. They also show what phase a compound is in. • Toxins are substances that interact with living organisms and cause harm.

  13. Check-in • Consider this reaction between sodium cyanide and a solution of hydrochloric acid: NaCN(s)  HCl(aq)  NaCl(aq)  HCN(g) • Write an interpretation of the chemical equation. • Sodium cyanide is highly toxic. What is the most likely way it will enter the body?

  14. Lesson 2: Making Predictions • Observing Change

  15. Day 2 ChemCatalyst • Consider this chemical equation: AgNO3(aq)  KCl(aq)  KNO3(aq)  AgCl(s) • a) What do you expect to observe if you carry out this reaction in a laboratory? • b) Write an interpretation of the chemical equation, describing what is taking place.

  16. Key Question • How can you predict what you will observe based on a chemical equation?

  17. You will be able to: • relate chemical equations to real-world observations • make predictions based on chemical equations

  18. Discussion Notes AgNO3(aq)  KCl(aq)  KNO3(aq)  AgCl(s)

  19. Discussion Notes (cont.) • Chemical equations contain certain information that you can use to predict what you might observe if a procedure is performed. • Sometimes change is described by more than one chemical equation. • Chemical equations allow you to track changes in matter on an atomic level. • There is some information that a chemical equation can’t provide.

  20. Wrap Up • How can you predict what you will observe based on a chemical equation? • Chemical equations allow chemists to predict and track changes in matter. They indicate how many products are formed, what those products are, and the phase of each product. • Observations of chemical procedures provide information not covered by a chemical equation (and vice versa). Observations alone cannot tell you what substances are present.

  21. Check-in • Examine this chemical equation. Write an interpretation of the chemical equation, describing what is taking place. CaCl2(aq) + 2NaOH(aq)  Ca(OH)2(s)  2NaCl(aq)

  22. Lesson 3: Spare Change • Physical Versus Chemical Change

  23. Key Question • How are changes in matter classified?

  24. Day 3 ChemCatalyst • Does this chemical equation describe a physical change or a chemical change? • Explain how you can tell. C17H17O3N(s) + 2C4H6O3(l)  C21H21O5N(s) + 2C2H4O2(l)

  25. You will be able to: • define physical and chemical change and explain the gray areas between them • classify chemical equations as representing physical changes or chemical changes

  26. Discussion Notes • Physical changes are changes in the appearance or form of a substance. • Chemical changes produce new substances with new properties. • Physical change: A change in matter in which a substance changes form but not identity. • Chemical change: A change in matter that results in the formation of a new substance or substances with new properties.

  27. Discussion Notes (cont.) • CoCl2(s)  CoCl2(aq) • CoCl2(aq) + Ca(OH)2(aq)  Co(OH)2(s) + CaCl2(aq) • It is not always possible to distinguish between physical and chemical change based on observations alone. • It is possible to argue that dissolving a substance in water changes the properties of that substance.

  28. Discussion Notes (cont.) • Ionic compounds do not dissolve in the same way as molecular solids. • The dissolving of ionic solids can be shown with a type of equation that stresses the formation of ions in solution. • CaCl2(s)  CaCl2(aq) CaCl2(s)  Ca2(aq) + 2Cl−(aq)

  29. Wrap Up • How are changes in matter classified? • Chemical changes involve the formation of new substances. • Physical changes, such as phase changes, involve a change in form. • Dissolving generally is considered a physical change, but it has something in common with chemical change as well. • Chemical equations often provide more straightforward information about the type of change than do mere observations.

  30. Lesson 4: Some Things Never Change • Conservation of Mass

  31. Key Question • How does mass change during a chemical or physical change?

  32. Lesson 5: Atom Inventory • Balancing Chemical Equations

  33. Key Question • How do you balance atoms in a chemical equation?

  34. Day 4 ChemCatalyst • Consider this reaction: • a. Describe what you will observe when sodium carbonate, Na2CO3(aq), and calcium chloride, CaCl2(aq), are mixed. • b. Will the mass increase, decrease, or stay the same after mixing? Explain. • c. Does this reaction obey the law of conservation of mass? Why or why not? Na2CO3(aq) + CaCl2(aq)  2NaCl(aq) + CaCO3(s)

  35. Wrap Up • How does mass change during a chemical or physical change? • Individual atoms are conserved in chemical reactions and physical changes: The number of atoms of each element remains the same from start to finish. • Mass is conserved in chemical reactions: The total mass of the products equals the total mass of the reactants.

  36. Wrap Up (cont.) • The law of conservation of mass states that matter can be neither created nor destroyed in physical and chemical changes. Matter is conserved. • Gases have mass.

  37. Check-in • Consider this reaction: • Describe what you will observe when copper (II) carbonate, CuCO3(s), and sulfuric acid, H2SO4(aq), are mixed. • Will the mass increase, decrease, or stay the same after mixing? Explain. CuCO3(s) + H2SO4(aq)  CO2(g) + CuSO4(aq) + H2O(l)

  38. You will be able to: • balance a simple chemical equation • explain the role of coefficients in chemical equations

  39. Discussion Notes • A balanced chemical equation is one that shows the true mathematical relationship between the reactants and the products in a chemical reaction.

  40. Discussion Notes (cont.) • CH4(g) + O2(g)  CO2(g) + H2O(g)

  41. Discussion Notes (cont.) • CH4(g) + O2(g)  CO2(g) + 2H2O(g)

  42. Discussion Notes (cont.) • CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)

  43. Discussion Notes (cont.)

  44. Discussion Notes (cont.) • There are two types of numbers in a chemical equation: coefficients and subscripts. • Coefficients: The coefficients in a chemical equation are the numbers in front of the chemical formulas of the reactants and products. They show the correct ratio in which the reactants combine to form the products. • The coefficients in a chemical equation indicate how many “units” of an element or a compound you have.

  45. Wrap Up • How do you balance atoms in a chemical equation? • In order for matter to be conserved, the number of atoms on both sides of a chemical equation must be equal. • When a chemical equation is balanced, it indicates how many molecules or moles of each substance take part in a reaction and how many molecules or moles of the product(s) are produced.

  46. Check-in • Balance this equation: • Ca(s) + O2(g)  CaO(s)

  47. Lesson 6: What’s Your Reaction? • Types of Reactions

  48. Day 6 ChemCatalyst • Consider these reactions: • CaCO3(aq)  CaO(aq) + CO2(g) • CO2(g) + NaOH(aq)  NaHCO3(aq) • How are these two reactions different? • How would you describe, in words, what happens to the reactants in each case?

  49. Key Question • How do atoms rearrange to form new products?

  50. You will be able to: • identify patterns in chemical equations that reflect different types of reactions • classify chemical equations as representing combination, decomposition, single exchange, or double exchange reactions

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