Investigation II: Tracking Toxins Toxins Unit Investigation II: Tracking Toxins Lesson 1: The Language of Change Lesson 2: Making Predictions Lesson 3: Spare Change? Lesson 4: Scrub the Air Lesson 5: Some Things Never Change Lesson 6: Atom Inventory Lesson 7: Toxins At Work

Toxins Unit – Investigation II Lesson 1: The Language of Change

NaCN (s) + HCl (aq)  NaCl (aq) + HCN (g) ChemCatalyst Below is a chemical “sentence” describing the formation of a very toxic substance, hydrogen cyanide. NaCN (s) + HCl (aq)  NaCl (aq) + HCN (g) What kinds of information does this chemical notation contain? List at least four pieces of information contained in this chemical notation. Unit IV • Investigation II-X

The Big Question How do chemists describe chemical reactions, and what kinds of evidence do they look for to verify that their descriptions are correct? Unit IV • Investigation II-X

You will be able to: Identify the different components of a chemical equation and use that information to predict the outcome of the reaction it represents. Unit IV • Investigation II-X

Notes The previous chemical “sentence” is called a chemical equation. A chemical equation describes change. (cont.) Unit IV • Investigation II-X

Notes (cont.) The substances you start with before the change takes place are on the left side of the arrow. If there is more than one substance and they react with one another, they are called reactants. The substances you end up with after the change takes place are on the right side of the arrow. They are often referred to as products. Unit IV • Investigation II-X

Activity Purpose: In this experiment, you will carry out the reaction between hydrochloric acid and sodium bicarbonate, and then do some analysis of the products that form. (cont.) Unit IV • Investigation II-X

(cont.) Safety note: Hydrochloric acid is dangerous and causes burns. Do not get hydrochloric acid on your skin. In case of a spill, rinse with large amounts of water. Wear goggles. (cont.) Unit IV • Investigation II-X

(cont.) (cont.) Symbol What it Represents HCl NaCl (aq) H2O + (l) NaHCO3 CO2  (g) (cont.) Unit IV • Investigation II-X

(cont.) Observations During Reaction After Reaction During Heating After Heating Unit IV • Investigation II-X

Making Sense Describe how a chemical equation keeps track of a chemical reaction. Unit IV • Investigation II-X

NaCl(aq) + H2O(l) + CO2(g) Notes HCl(aq) + NaHCO3(aq)  NaCl(aq) + H2O(l) + CO2(g) Unit IV • Investigation II-X

NaCN (s) + HCl (aq)  NaCl (aq) + HCN (g) Check-In Consider the following reaction between sodium cyanide and a solution of hydrochloric acid. NaCN (s) + HCl (aq)  NaCl (aq) + HCN (g) Describe in detail what you would observe if you carried out this reaction. Describe the products that you would have. Unit IV • Investigation II-X

Wrap-Up Chemical equations help chemists keep track of the substances involved in chemical and physical changes. Chemical equations indicate the reactants and products of chemical reactions. Unit IV • Investigation II-X

Toxins Unit – Investigation II Lesson 2: Making Predictions

ChemCatalyst Consider the following reaction: AgNO3 (aq) + KCl (aq)  KNO3(aq) + AgCl(s) What do you expect to observe if you carried out the reaction? Translate the above chemical equation into writing, describing what is taking place. Unit IV • Investigation II-X

The Big Question How do chemists predict the products of reactions and write the chemical reactions they represent? Unit IV • Investigation II-X

You will be able to: Use chemical reactions to predict expected real-world observations and use real-world observations to write the chemical reaction they represent. Unit IV • Investigation II-X

Activity Purpose: This lesson provides you with practice translating chemical equations. You will have the opportunity to check you predictions by completing the laboratory procedure associated with each equation. (cont.) Unit IV • Investigation II-X

(cont.) Safety note: Do not touch the dry ice with your fingers. It causes burns. NaOH, Ca(OH)2, and NH4OH are caustic. Do not get them on your skin. In case of a spill, rinse with large amounts of water. Wear goggles. (cont.) Unit IV • Investigation II-X

b) CO2 (s) + H2O (l)  H2CO3 (aq) Reaction Predictions Observations Dry ice 1 CO2 (s)  CO2 (g) 2 a) CO2 (s)  CO2 (g) b) CO2 (s) + H2O (l)  H2CO3 (aq) 3 CO2 (s) + Ca(OH)2 (aq)  CaCO3 (s) + H2O (aq) Unit IV • Investigation II-X

b) CaCl2(s)  Ca2+(aq) + 2 Cl– (aq) Reaction Predictions Observations Calcium chloride 4 a) CaCl2 (s)  CaCl2 (aq) b) CaCl2(s)  Ca2+(aq) + 2 Cl– (aq) 5 CaCl2 (aq) + 2 NaOH (aq)  Ca(OH)2 (s) + 2 NaCl (aq) 6 CaCl2 (s) + CuSO4 (s)  CaCl2 (s) + CuSO4 (s) Unit IV • Investigation II-X

b) CuSO4 (s)  Cu2+ (aq) + SO42–(aq) Reaction Predictions Observations Copper sulfate 7 a) CuSO4 (s)  CuSO4 (aq) b) CuSO4 (s)  Cu2+ (aq) + SO42–(aq) 8 CuSO4 (s) + 4 NH4OH (aq)  Cu(NH3)4SO4 (aq) + 4H2O (l) 9 CuSO4 (aq) + Zn (s)  Cu (s) + ZnSO4 (aq) Unit IV • Investigation II-X

Making Sense Make a list of all the different types of things that you observed today that are associated with changes in matter. Unit IV • Investigation II-X

Check-In No Check-In exercise. Unit IV • Investigation II-X

Wrap-Up Chemical equations allow chemists to predict and track changes in matter. Unit IV • Investigation II-X

Toxins Unit – Investigation II Lesson 3: Spare Change?

ChemCatalyst The following two equations both describe what happens when dry ice is placed in water: CO2 (s)  CO2 (g) CO2 (s) + H2O (l)  H2CO3 (aq) What differences do you see in these two equations? Why do you think two equations are needed to describe what happens? Unit IV • Investigation II-X

The Big Question What are the differences between physical changes and chemical changes? Unit IV • Investigation II-X

You will be able to: Convert back and forth between chemical reaction notation and real world observations, and identify each change as either chemical or physical. Unit IV • Investigation II-X

Notes In a chemical equation describing a physical change, the chemical formulas do not change in going from reactants to products. However, the phase (s, l, & aq) does change. In a chemical equation describing a chemical change, the chemical formulas of the reactants are different from those of the products. Unit IV • Investigation II-X

Activity Purpose: This activity provides you with practice distinguishing between physical and chemical changes using only the chemical equations. Unit IV • Investigation II-X

Making Sense Compare your observations for each reaction to the chemical equations. If you were asked to classify a reaction as a physical or chemical change, which would you prefer to have, a set of observations or chemical equations? Explain your thinking. Unit IV • Investigation II-X

CaCl2(s)  Ca2+(aq) + 2 Cl– (aq) Notes CaCl2 (s)  CaCl2 (aq) CaCl2(s)  Ca2+(aq) + 2 Cl– (aq) Unit IV • Investigation II-X

Check-In Does the following chemical equation describe a physical change or a chemical change? Explain how you can tell. C17H17O3N(s) + 2C4H6O3(l)  C21H21O5N(s) + 2 C2H4O2(l) Unit IV • Investigation II-X

Wrap-Up Chemical changes involve the formation of new substances. Physical changes, such as phase changes, involve a change in form. Chemical equations often provide more straightforward information about the type of change than mere observations. Unit IV • Investigation II-X

Toxins Unit – Investigation II Lesson 4: Scrub the Air

ChemCatalyst In enclosed spaces such as on a space station or in a submarine, the breathing of the occupants causes a natural build up of carbon dioxide, CO2. Too much CO2 in the air is highly toxic. List two ways to use chemical change to eliminate CO2 (g). Unit IV • Investigation II-X

The Big Question How does molecular bonding affect the outcome of chemical reactions? Unit IV • Investigation II-X

You will be able to: Classify certain chemical reactions as either combination or decomposition and predict the possible products when given specific reactants. Unit IV • Investigation II-X

AB  A + B (decomposition) Notes In a decomposition reaction, one reactant is broken apart into two or more substances. In a combination reaction, two or more substances combine to form a single product. AB  A + B (decomposition) A + B  AB (combination) (cont.) Unit IV • Investigation II-X

(cont.) CaCO3  CaO + Unit IV • Investigation II-X

Activity Purpose: You will compare different kinds of chemical reactions and learn the notation used to write chemical reactions. Unit IV • Investigation II-X

Making Sense Explain how you can predict the products of the decomposition of NaCl. Explain how you can predict the product of the combination of carbon and hydrogen. Unit IV • Investigation II-X

Check-In List a possible product of the following combination reaction: CH4 (g) + O2 (g)  Unit IV • Investigation II-X

Wrap-Up The substances in chemical reactions obey the bonding rules we have learned for ionic and covalent substances. A decomposition reaction in one in which one reactant is broken apart into two or more substances. A combination reaction is one in which two or more substances combine to form a single product. Unit IV • Investigation II-X

Toxins Unit – Investigation II Lesson 5: Some Things Never Change

ChemCatalyst Consider the following reaction. Na2CO3 (aq) + CaCl2 (aq)  NaCl (aq) + CaCO3 (s) Describe what you will observe when Na2CO3 (aq) and CaCl2 (aq) are mixed. Will the mass increase, decrease, or stay the same after mixing? Explain. Unit IV • Investigation II-X

The Big Question What is the relationship between the mass of reactants and the mass of products of a chemical reaction? Unit IV • Investigation II-X

You will be able to: Explain the relationship between the mass of reactants and the mass of products of a chemical reaction. Unit IV • Investigation II-X

Activity Purpose: In this activity, you will explore conservation of matter and how it applies to the world around you. (cont.) Unit IV • Investigation II-X

(cont.) (cont.) Weight before mixing Predict the weight after mixing Observations after mixing Weight after mixing Na2CO3 (aq) + CaCl2 (aq) Na2CO3 (aq) + C2H4O2 (aq) (cont.) Unit IV • Investigation II-X

(cont.) Chemical Reaction 1: (cont.) > = < ? Reactants Products Unit IV • Investigation II-X

(cont.) Chemical Reaction 2: > = < ? Reactants Products Unit IV • Investigation II-X

Making Sense In your own words, explain what happens to matter and its mass when a chemical reaction or physical change occurs. Unit IV • Investigation II-X

Notes Law of conservation of matter: Matter can be neither created nor destroyed in chemical reactions. This means that in chemical reactions and physical changes atoms do not come in and out of existence. They are simply rearranged. Since atoms have mass, the mass does not change. Unit IV • Investigation II-X

CO2 (g) + CuSO4 (aq) + H2O (l) Check-In Consider the following reaction: CuCO3 (s) + H2SO4 (aq)  CO2 (g) + CuSO4 (aq) + H2O (l) Describe what you will observe when CuCO3 (s) and H2SO4 (aq) are mixed. Will the mass increase, decrease, or stay the same after mixing? Explain. Will the weight increase, decrease, or stay the same after mixing? Explain. Unit IV • Investigation II-X

Wrap-Up Individual atoms are conserved in chemical reactions and physical changes: the number of atoms of each element remains constant from start to finish. Matter is conserved in chemical reactions: the total mass of the products equals the total mass of the reactants. Gases have mass. Unit IV • Investigation II-X

Toxins Unit – Investigation II Lesson 6: Atom Inventory

ChemCatalyst Does the following equation obey the law of conservation of matter? Why or why not? CuCl2(aq) + Na2S (aq)  CuS (s) + NaCl (aq) Unit IV • Investigation II-X

The Big Question What does it mean to “balance” a chemical equation? Unit IV • Investigation II-X

You will be able to: Use the concept of a balanced chemical equation to account for the atoms involved in a chemical reaction. Unit IV • Investigation II-X

Notes The subscripts in a chemical equation indicate how many atoms are in the chemical formula for that substance. The large numbers in front of chemical formulas are called coefficients. They indicate how many parts of that substance there are in a reaction. Unit IV • Investigation II-X

Activity Purpose: In this activity, you will practice balancing chemical reactions. (cont.) Unit IV • Investigation II-X

(cont.) The four unbalanced reactions are given below: 1. Zn(s) + HCl(aq)  ZnCl2(aq) + H2(g) 2. O2(g) + H2(g)  H2O(l) 3. O2(g) + CH4(g)  CO2 + H2O(l) 4. NO2 + H2O(l)  HNO3(aq) + NO(g) Unit IV • Investigation II-X

Making Sense The balanced equations are shown below, with the new coefficients highlighted in bold. 1. Zn (s) + 2 HCl (aq)  ZnCl2 (aq) + H2 (g) 2. O2 (g) + 2 H2 (g)  H2O (l) 3. 2 O2 (g) + CH4 (g)  CO2 (g) + 2 H2O (l) 4. 3 NO2 (g) + H2O (l)  2 HNO3 (aq) + NO (g) (cont.) Unit IV • Investigation II-X

(cont.) C2H6 + 4 O2  2 CO2 + 3 H2O (cont.) Unit IV • Investigation II-X

(cont.) Example #1: Balance the following equation NO (g) + O2 (g)  NO2 (g) (cont.) Unit IV • Investigation II-X

(cont.) Example #2: Balance the following equation for rusting iron. Fe (s) + O2 (g)  Fe2O3 (s) Unit IV • Investigation II-X

Check-In Balance the following equation. Ca + O2  CaO Unit IV • Investigation II-X

Wrap-Up In order to conserve matter, the number of atoms on both sides of a chemical equation must be equal. When an equation is balanced it tells you how many molecules or moles of each substance take part in a reaction and how many molecules or moles of product (s) are produced. Unit IV • Investigation II-X

Toxins Unit – Investigation II Lesson 7: Toxins At Work

ChemCatalyst Hemoglobin (Hb) is the molecule in your blood that carries oxygen throughout your body. Ca3(PO4)2 (s), calcium phosphate, is the main compound in bones and teeth. (cont.) Unit IV • Investigation II-X

O2–Hb (aq) + CO (g)  CO–Hb (aq) + O2 (g) (cont.) Below are two reactions that might take place in your body, one involving carbon monoxide, CO, and the other involving lead chloride, PbCl2. O2–Hb (aq) + CO (g)  CO–Hb (aq) + O2 (g) Ca3(PO4)2 (s) + Pb(NO3)2 (aq)  Pb3(PO4)2(OH) (s) + Ca(NO3)2 (aq) Which atoms rearranged in each case? Why are CO and PbCl2 toxic? Unit IV • Investigation II-X

The Big Question How do toxins act upon our bodies? Unit IV • Investigation II-X

You will be able to: Recognize single displacement and double displacement reactions and predict the possible products when given specific reactants. Unit IV • Investigation II-X

Notes Single displacement: A single displacement reaction begins with an element and a compound. The compound breaks apart and then one piece combines with the element while the other piece is left in the elemental form. The general reaction can be written as AB + C  AC + B, where C displaces B. (cont.) Unit IV • Investigation II-X

Notes (cont.) Double displacement: A double displacement reaction begins with two compounds that break apart. Their parts then recombine into two new products. The general reaction can be written as AB + CD  AD + CB, where B and D exchange with one another (or A and C exchange with one another). (cont.) Unit IV • Investigation II-X

Notes (cont.) Groups of atoms are called polyatomic ions. The atom or groups of atoms that move around in chemical reactions are called species. (cont.) Unit IV • Investigation II-X

Notes (cont.) Single displacement reactions: Cl2 + CaI2  [CaCl2 + I2] Note that the products [Ca + 2ClI] are not produced. Mg + 2HCl  [H2 + MgCl2] Note that the products [Cl2 + MgH2] are not produced. (cont.) Unit IV • Investigation II-X

Notes (cont.) Double displacement reactions: CsF + NaOH  [CsOH + NaF] Note that the products [CsNa + FOH] are not produced. PbI2 + 2K2S  [PbS + 2KI] Note that the products [K2Pb + SI2] are not produced. Unit IV • Investigation II-X

Activity Purpose: In this worksheet, you will practice predicting the products of displacement reactions. Unit IV • Investigation II-X

Making Sense Explain in a step-by-step fashion how you completed the above equations. Suppose you drank a solution containing the toxin PbI2. Suggest how this toxin may act in your body. Unit IV • Investigation II-X

Notes Combination: A + B  AB Decomposition: AB  A + B Single displacement: AB + C  AC + B Double displacement: AB + CD  AD + BC Unit IV • Investigation II-X

Check-In Thallium is the 81st element on the periodic table. Not that long ago, thallium compounds were used both as rat poison and in hair removal products. However, these compounds are quite toxic to humans and hair loss is one of the first signs of thallium poisoning. Predict the products of the following reaction and balance the equation. TlCl3 + LiOH  Unit IV • Investigation II-X

Wrap-Up Many chemical reactions can be classified as displacement reactions, in which one part of a compound is exchanged by another. Toxins act by displacing pieces of compounds in your body. Unit IV • Investigation II-X