Chemical Reactions Chapter 5 Dr. Victor Vilchiz.

Chemical Reactions Chapter 5 Dr. Victor Vilchiz

Solution Components In order to have a solution we must have at least “TWO” components. The Solvent which is the compound present in biggest abundance, water in most cases presented in this chapter. The Solute which is the “impurity” or compound present in the smallest amount. The resulting mixture is the solution.

Dissolving Ionic Compounds
Some compounds dissociate when placed in water. This does not mean we will get the constituent elements once in water. For example: when table salt (NaCl) is added to a container with water as soon as the grains of salt touch the water NaCl ceases to exist. In solution, we have the component ions Na+ and Cl-

Ions in Aqueous Solution
Ionic Theory of Solutions Many ionic compounds dissociate into independent ions when dissolved in water These compounds that “freely” dissociate into independent ions in aqueous solution are called electrolytes. Their aqueous solutions are capable of conducting an electric current. Figure 4.2 illustrates this.

Ionic Theory of Solutions Electrolytes are substances that dissolve in water to give an electrically conducting solution. Thus, in general, ionic solids that dissolve in water are electrolytes. Some molecular compounds, such as acids, also dissociate in aqueous solution and are considered electrolytes.

Ionic Theory of Solutions Molecular compounds that dissolve usually do not dissociate into ions. These compounds are referred to as nonelectrolytes. They dissolve in water to give a nonconducting solution. Conductivity Test

Ionic Theory of Solutions There are few molecular compounds (acids & alcohols) that upon solvation dissociate into ions, this is due to the weak interaction between the atoms. The resulting solution is electrically conducting, and so we say that the molecular substance is an electrolyte.

Does water conduct? As we have seen current/energy does not flow in a circuit unless there are “free” ions in solution. This means that a sample or “pure” water will not conduct electricity or current. Tap water conducts electricity and current because there are dissolved ions present put there on purpose and some from pipes dissolving.

Strong Electrolytes Ionic Theory of Solutions Electrolytes can be separated into two different categories Strong electrolytes. A strong electrolyte is an electrolyte that exists in solution almost entirely as ions. The solvation process is represented by a one-way arrow in the chemical reaction implying a path of no return.

Weak Electrolytes Ionic Theory of Solutions Weak electrolytes.
Ionic Theory of Solutions Weak electrolytes. A weak electrolyte is an electrolyte that dissolves in water to give a relatively small percentage of ions. The solvation process is presented by a double sided arrow implying an equilibrium between reactants and products. Most soluble molecular compounds are either nonelectrolytes or weak electrolytes. Strength Test

Why dissociation? Dissociation takes place because the attractive force between the ions can be overcome by other forces. The solvent is able to surround ions and provide stronger forces of attraction. Why? If water has no charge how can it create this attractive forces that compete with coulombic interaction? This can be explained if we look at the electron distribution in water.

Polarity Electron distribution
Electron distribution If we draw a water molecule representing its true shape we will see that the electrons are not evenly distributed. While there are no real charges the difference in electron density acts as a separation of charges which leads to a pseudo ionic behavior. The Red represents a high density of electrons (-); the blue represents a low density of electrons (+). The separation of charge we see in water is labeled as the polarity of the molecule; the higher the difference in electron density the higher the polarity of the molecule.

Polarity The polarity of a molecule depends mainly on two factors
The polarity of a molecule depends mainly on two factors Shape of the molecule Composition It is represented by an arrow with its head pointing towards the negative charge side and a crossed tail on the positive side of the molecule

Polarity and Solvation
Molecules that have a separation of charges are called polar molecules When ionic compounds are added to water, the ions break apart and the water molecules arrange themselves so the negative end (O) points towards the cations and the positive end (H’s) point towards the anions. Representation

Insoluble Compounds No compound is really insoluble.
No compound is really insoluble. However, if the amount that dissolves is compared to the starting amount it is found to be insignificant that they are said to be insoluble. Example NaCl in =365g/L AgCl in =0.009g/L

Chemical Equations Molecular and Ionic Equations A molecular equation is one in which the reactants and products are written as if they were molecules, even though they may actually exist in solution as ions. Note that Ca(OH)2, Na2CO3, and NaOH are all soluble compounds but CaCO3 is not.

Chemical Equations Molecular and Ionic Equations An ionic equation, however, represents strong electrolytes as separate independent ions. This is a more accurate representation of the way electrolytes behave in solution. The downward arrow represents a precipitate which will fall to the bottom of the container

Chemical Equations Complete and net ionic equations
Molecular and Ionic Equations A complete ionic equation is a chemical equation in which strong electrolytes (such as soluble ionic compounds) are written as separate ions in solution. Complete and net ionic equations (strong) (strong) (insoluble)

Chemical Equations Complete and net ionic equations.
Molecular and Ionic Equations Complete and net ionic equations. A net ionic equation is a chemical equation from which the spectator ions have been removed. A spectator ion is an ion in an ionic equation that does not take part in the reaction (present on both sides of the arrow in the same state.

Molecular and Ionic Equations Complete and net ionic equations Let’s try an example. First, we start with a molecular equation. Nitric acid, HNO3, and magnesium nitrate, Mg(NO3)2, are both strong electrolytes.

Molecular and Ionic Equations Complete and net ionic equations Separating the strong electrolytes into separate ions, we obtain the complete ionic equation. Note that the nitrate ions did not participate in the reaction. These are spectator ions.

Molecular and Ionic Equations Complete and net ionic equations Eliminating the spectator ions results in the net ionic equation. This equation represents the “essential” reaction.

Types of Chemical Reactions
Most of the reactions we will study fall into one of the following categories Precipitation Reactions Acid-Base Reactions Oxidation-Reduction Reactions

Precipitation Reactions In a precipitation reaction we start with 2 soluble compounds dissolved in water and when mixed they produce at least one insoluble compound, which precipitates (falls to the bottom). For example, the reaction of sodium chloride with silver nitrate forms AgCl(s), an insoluble precipitate.

Precipitation Reactions
Does this mean that if we mixed two soluble ionic compounds we will always form a precipitate? NO What is the driving force for precipitation reactions? While the formation of the solid can be viewed as the driving force, it is the removal of ions from solution that is the true driving force.

Precipitation Reactions Solubility rules Substances vary widely in their solubility, or ability to dissolve, in water. For example, NaCl is very soluble in water whereas calcium carbonate, CaCO3, is insoluble in water. (see Figure 4.5)

Precipitation Reactions Predicting Precipitation Reactions. To predict whether a precipitate will form, we need to look at potential insoluble products. Table 4.1 lists eight solubility rules for ionic compounds. These rules apply to the most common ionic compounds.

Precipitation Reactions Predicting Precipitation Reactions. Suppose you mix together solutions of nickel(II) chloride, NiCl2, and sodium phosphate, Na3PO4. How can you tell if a reaction will occur, and if it does, what products to expect?

Precipitation Reactions Predicting Precipitation Reactions. Precipitation reactions have the form of an “exchange reaction.” An exchange (or metathesis) reaction is a reaction between compounds that, when written as a molecular equation, appears to involve an exchange of cations and anions.

Precipitation Reactions Predicting Precipitation Reactions. Now that we have predicted potential products, we must balance the equation. We must verify that NiCl2 and Na3PO4 are soluble and then check the solubilities of the products.

Precipitation Reactions Predicting Precipitation Reactions. Table 4.1 indicates that our reactants, nickel(II) chloride and sodium phosphate are both soluble. (aq) (aq) (s) (aq) Looking at the potential products we find that nickel(II) phosphate is not soluble although sodium chloride is.

Precipitation Reactions Predicting Precipitation Reactions. We predict that a reaction occurs because nickel(II) phosphate is insoluble and precipitates from the reaction mixture. To see the reaction that occurs on the ionic level, we must rewrite the molecular equation as an ionic equation.

Precipitation Reactions Predicting Precipitation Reactions. First write strong electrolytes (the soluble ionic compounds) in the form of ions to obtain the complete ionic equation

Precipitation Reactions Predicting Precipitation Reactions. After canceling the spectator ions, you obtain the net ionic equation. This equation represents the “essential” reaction.

Acid-Base Reactions Acids and bases are some of the most important electrolytes. (see Table 4.2) They can cause color changes in certain dyes called acid-base indicators. Household acids and bases. (see Figure 4.7) Red cabbage juice as an acid-base indicator. (see Figure 4.8)

Acid-Base Reactions The Ancient Concept In ancient times acids and bases had a different meaning. An acid was defined as a sour substance. A Base was defined as a substance that was both bitter and slippery

Acid-Base Reactions The Arrhenius Concept The Arrhenius concept defines acids as substances that contain H and produce hydrogen ions, H+, when dissolved in water. An example is nitric acid, HNO3, a molecular substance that dissolves in water to give H+ and NO3-.

Acid-Base Reactions The Arrhenius Concept The Arrhenius concept defines bases as substances that contain OH and produces hydroxide ions, OH-, when dissolved in water. An example is sodium hydroxide, NaOH, an ionic substance that dissolves in water to give sodium ions and hydroxide ions. He really meant contain OH-

Acid-Base Reactions The Arrhenius Concept However, there are substances that we now classify as bases or acids but they do not follow the Arrhenius definition. For example ammonia, NH3, is a base but it does not contain OH-, Therefore we need a second definition that can take compounds like ammonia into account.

Acid-Base Reactions The Brønsted-Lowry Concept The Brønsted-Lowry concept of acids and bases avoids the problems of composition inherent in the Arrhenius definitions by basing the definitions on the transfer of protons (H+) instead. In this view, acid-base reactions are proton-transfer reactions and there must be two reactions taking place at once.

Acid-Base Reactions The Brønsted-Lowry Concept The Brønsted-Lowry concept defines an acid as the species (molecule or ion) that donates a proton (H+) to another species in a proton-transfer reaction. A base is defined as the species (molecule or ion) that accepts the proton (H+) in a proton-transfer reaction.

Acid-Base Reactions The Brønsted-Lowry Concept In the reaction of ammonia with water, H+ The H2O molecule is the acid because it donates a proton. The NH3 molecule is a base, because it accepts a proton. Likewise NH4+ is an acid because it can donate one of the protons, and OH- is a base since it can accept a proton.

Acid-Base Reactions The Brønsted-Lowry Concept The H+(aq) ion due to its small size has a very high positive charge density. The polarity of the water molecules allowed for the water molecules to be closely associated with the proton making it appear as if the hydrogen ion was bonded to water molecules as it moves. This “mode of transportation” for the H+ ion is called the hydronium ion.

Acid-Base Reactions The Brønsted-Lowry Concept The dissolution of nitric acid, HNO3, in water is therefore a proton-transfer reaction where HNO3 is an acid (proton donor) and H2O is a base (proton acceptor). H+

Water and Acid/Base Rxns
Acid-Base Reactions As we have seen there are cases in which water: Donates a Proton acting as an acid. Accepts a Proton acting as a base. Molecules can act both as acid or base depending on the environment they are in are called amphiprotic.

Acid-Base Reactions In summary, the Arrhenius concept is very basic and the Brønsted-Lowry concept was developed to cover cases left out; however, in water they are almost the same. Arrhenius Concept acid: proton (H+) donor to the water base: hydroxide ion (OH-) donor to the water

Acid-Base Reactions In summary, any Arrhenius acid/base is also a Brønsted-Lowry acid/base but not the other way around. The Brønsted-Lowry concept acid: proton (H+) donor to anything base: proton (H+) acceptor from anything

Acid/Base Concepts Acid-Base Reactions Lewis Acid/Base Concept
Bronsted-Lowry Acid/Base Concept Arrhenius Acid/Base Concept

Acid-Base Reactions Arrhenius Acids/Bases Acids can be separated into two subcategories depending on the strength of the acid. The Strength of the acid is determined by how easily it releases the proton. The easier it is to give the proton away the stronger the acid. A strong acid is an acid that ionizes completely in water; it is a strong electrolyte.

Strong Acids Acid-Base Reactions
Furthermore, if the proton comes off a molecule easier than it comes off from the solvent molecule then that acid is treated as having the same strength as the solvent, this is the leveling effect. HNO3 HCl HClO4 HBr H2SO4 HI These are 6 compounds that give up their proton readily, hence they are strong acids in water.

These are 6 common weak acids
Acid-Base Reactions Weak Acids A weak acid is a molecule that holds on to its proton tightly allowing for a very small percentage of ionization, it is a weak electrolyte. HCN HF HC2H3O2 H2S H3PO4 NH4+ These are 6 common weak acids

Strong Bases Acid-Base Reactions Strong Bases
A strong base just like a strong acid is a compound that dissociates completely. Moreover, it readily accepts the proton given up by an acid. These are 6 compounds that are happy to accept any proton given up by an acid. LiOH Ca(OH)2 NaOH Sr(OH)2 KOH Ba(OH)2

Weak Bases Weak Bases Acid-Base Reactions
A weak base is a base that is only partially ionized in water; it is a weak electrolyte. It does not want to accept a proton and if it does the new compound/ion is likely to give it up the first chance it has.

Acid-Base Reactions Strong and Weak Acids and Bases You will find it important to be able to identify an acid or base as strong or weak. When you write an ionic equation, strong acids and bases are represented as separate ions. Weak acids and bases are represented as undissociated “molecules” in ionic equations since they hardly dissociate.

Acid-Base Reactions Neutralization Reactions One of the chemical properties of acids and bases is that they neutralize one another. A neutralization reaction is a reaction of an acid and a base that results in an ionic compound and water. The ionic compound that is the product of a neutralization reaction is called a salt. acid base salt

Acid-Base Reactions Neutralization Reactions The net ionic equation for each acid-base neutralization reaction involves a transfer of a proton. Consider the reaction of the strong acid , HCl(aq) and a strong base, LiOH(aq).

Acid-Base Reactions Neutralization Reactions Writing the strong electrolytes in the form of ions (refer to Table 4.1 and 4.3) gives the following complete ionic equation.

Acid-Base Reactions Neutralization Reactions Canceling the spectator ions results in the net ionic equation. Note the proton transfer. H+

Acid-Base Reactions Neutralization Reactions In a reaction involving HCN(aq), a weak acid, and KOH(aq), a strong base, the product is KCN, a strong electrolyte Referring to Tables 4.1, 4.2 and 4.3, we obtain this net ionic equation: H+ Note the proton transfer.

Acid-Base Reactions Acid-Base Reactions with Gas Formation Carbonates react with acids to form CO2, carbon dioxide gas. Sulfites react with acids to form SO2, sulfur dioxide gas.

Gas Production in Neutralization Reactions
The previous two reactions are overall reactions of the actual molecular events.

Acid-Base Reactions Acid-Base Reactions with Gas Formation The Driving Force of Neutralization reactions like that in precipitation reactions is the removal of ions from solution in this case to form water. Sulfides react with acids to form H2S, hydrogen sulfide gas.

Working with Solutions
The majority of chemical reactions discussed so far occur in aqueous solution. When you run reactions in liquid solutions, it is convenient to dispense the amounts of reactants by measuring out volumes of reactant solutions and not mass.

Solution Stoichiometry
Molarity is the measurement of the concentration of a chemical in solution. The unit of molarity is the Molar (M). Example: Calculate the molarity of a solution made by dissolving 12.94g of Ca(OH)2 in enough water to make 1.23L of solution. (see Figure 4.19)

Oxidation-Reduction Reactions Types of Oxidation-Reduction Reactions Most of the oxidation-reduction reactions fall into one of the following simple categories: Combination Reactions Decomposition Reactions Displacement Reactions Combustion Reactions

Oxidation-Reduction Reactions Combination Reactions A combination reaction is a reaction in which two substances, usually two elements, combine to form a third substance. Sodium and chlorine combine in a fiery reaction. (see Figure)

Oxidation-Reduction Reactions Combination Reactions Other combination reactions involve compounds as reactants.

Oxidation-Reduction Reactions Decomposition Reactions A decomposition reaction is a reaction in which a single compound reacts to give two or more substances.

Oxidation-Reduction Reactions Displacement Reactions A displacement reaction (also called a single- replacement reaction) is a reaction in which an element reacts with a compound, displacing an element from it.

Oxidation-Reduction Reactions Combustion Reactions A combustion reaction is a reaction in which a substance reacts with oxygen, usually with the rapid release of heat to produce a flame.

Molarity Example: how many grams of ammonium nitrate are in a 172.7mL sample of 1.21M NH4NO3 solution?

(Molarity)(Volume) =moles
Diluting Solutions When diluting a solution the number of moles is constant. (Molarity)(Volume) =moles M1xV1 = n = M2xV2 So, as water is added, increasing the final volume, V2, the final molarity, M2, decreases. M2=M1xV1/V2

Acid Base Titrations A titration is a laboratory technique used to determine the concentration of a solution sample from the volume of a known concentration solution required to complete a given reaction. Titrations are usually used to determine the concentration of acids or bases.

Acid/Base Indicators Most acids and bases as well as the resulting salt solution are colorless. In order to determine when the reaction is complete, we must use chemical indicators. Chemical Indicators in the case of acid/base reactions are weak acids that have the property of changing colors when going from basic to acidic solutions or vice-versa. The most used acid/base indicator is phenolphthalein.

Indicators The job of the indicator is to signal to you the point when you are done with the experiment. The point when the color changes is defined as the end point. The equivalence point is not the same as the end point, ideally it should be but those occasions are rare. The equivalence point is when the amount of titrant added is exactly the amount needed to “neutralize” the analyte in the flask.

Oxidation-Reduction (RedOx) Reactions RedOx reactions are by far the most important type of reactions. RedOx reactions involve the transfer of electrons from one species to another. Oxidation is defined as the loss of electrons. Reduction is defined as the gain of electrons. Oxidation and reduction always occur simultaneously, since the electrons lost in the Oxidation must go somewhere.

Oxidation-Reduction Reactions The reaction of an iron nail with a solution of copper(II) sulfate, CuSO4, is an oxidation- reduction reaction. (see Figure 4.11) The molecular equation for this reaction is:

Oxidation-Reduction Reactions The net ionic equation shows the reaction of iron metal with Cu2+(aq) to produce iron(II) ion and copper metal. Loss of 2 e-1 oxidation Gain of 2 e-1 reduction

RedOx Reactions The species that is reduced itself causes another species to be oxidized and is therefore known as the oxidizing agent. Similarly, the species that are oxidized causes another to be reduced and is therefore known as the reducing agent. Note: An element is reduced/oxidized the compound containing that element is the oxidizing/reducing agent.

Oxidation-Reduction Reactions Oxidation Numbers The concept of oxidation numbers is a simple way of keeping track of electrons in a reaction. The oxidation number (or oxidation state) of an atom in a substance is the actual charge of the atom if it exists as a monatomic ion. Alternatively, it is hypothetical charge assigned to the atom in the substance by simple rules.

Oxidation Number Rules

Oxidation Numbers It is possible to predict the upper and lower limits of main group elements… The upper limit is equal to the group number The lower limit is the group number-8 Keep in mind couple things like… Oxygen will never have an ON=+6 and Fluorine will never have an ON=+7

Oxidation-Reduction Reactions Describing Oxidation-Reduction Reactions Look again at the reaction of iron with copper(II) sulfate. The Iron losses 2 electrons so it is oxidized and at the same time it is the reducing agent. The Copper gains 2 electrons and so it is reduced and at the same time it is the oxidizing agent.

Writing RedOx reactions
There are two ways to deal with RedOx reactions (balancing purposes): Treat them as any other reaction We can write this reaction in terms of two half-reactions. Driving force for these type of reactions is the exchange of electrons.

Oxidation-Reduction Reactions Describing Oxidation-Reduction Reactions A half-reaction is one of the two parts of an oxidation-reduction reaction. One involves the loss of electrons (oxidation) and the other involves the gain of electrons (reduction). oxidation half-reaction reduction half-reaction

Oxidation-Reduction Reactions Balancing Simple Oxidation-Reduction Reactions At first glance, the equation representing the reaction of zinc metal with silver(I) ions might appear to be balanced. However, a balanced equation must have a charge balance as well as a mass balance.

Oxidation-Reduction Reactions Balancing Simple RedOx Reactions As mentioned before we can split the reaction into two half-cells before balancing. You will learn this method in Chem 102 when you cover chapter 20. We will balance RedOx reactions using the Oxidation Number method.

Oxidation-Reduction Reactions Balancing Simple RedOx Reactions There are some steps to follow to balance these reactions. Assign ON to ALL elements in the reaction Identify the species that are oxidized/reduced Compute the number of e-s lost in OX and gained in RED draw lines between the two pairs including the number of e-s lost/gained Multiply one or both reactions so that both numbers match, use these factors as balancing coefficients Balance any other species that were not involved in the electron exchange.

Quantitative Analysis
Analytical chemistry deals with the determination of composition of materials-that is, the analysis of materials. Quantitative analysis involves the determination of the amount of a substance or species present in a sample of material.

Gravimetric Analysis Gravimetric analysis is a type of quantitative analysis in which the amount of a species in a material is determined by converting the species into a product that can be isolated and weighed. Precipitation reactions are often used in gravimetric analysis. The precipitate from these reactions is then filtered, dried, and weighed.

Gravimetric Analysis Consider the problem of determining the amount of lead in a sample of drinking water. Adding sodium sulfate (Na2SO4) to the sample will precipitate lead(II) sulfate. The PbSO4 can then be filtered, dried, and weighed. This figure shows a similar procedure.

Gravimetric Analysis Suppose a 1.00 L sample of polluted water was analyzed for lead(II) ion, Pb2+, by adding an excess of sodium sulfate to it. The mass of lead(II) sulfate that precipitated was mg. What is the mass of lead in a liter of the water? Express the answer as mg of lead per liter of solution.

Gravimetric Analysis First we must obtain the mass percentage of lead in lead(II) sulfate, by dividing the molar mass of lead by the molar mass of PbSO4, then multiplying by 100. Then, calculate the amount of lead in the PbSO4 precipitated.

Volumetric Analysis An important method for determining the amount of a particular substance is based on measuring the volume of the reactant solution. Titration is a procedure for determining the amount of substance A by adding a carefully measured volume of a solution with known concentration of B until the reaction of A and B is just complete. Volumetric analysis is a method of analysis based on titration.

Chemical Reactions Summary
Reactions often involve ions in aqueous solution. Many of these compounds are electrolytes. We can represent these reactions as molecular equations, complete ionic equations (with strong electrolytes represented as ions), or net ionic equations (where spectator ions have been canceled). Most reactions are either precipitation reactions, acid-base reactions, or oxidation-reduction reactions. Acid-base reactions are proton-transfer reactions. Oxidation-reduction reactions involve a transfer of electrons from one species to another.

Oxidation-reduction reactions are the most important type of reactions. Oxidation-reduction reactions usually fall into the following categories: combination reactions, decomposition reactions, displacement reactions, and combustion reactions. Molarity is defined as the number of moles of solute per liter of solution. Knowing the molarity allows you to calculate the amount of solute in a given volume of solution. Quantitative analysis involves the determination of the amount of a species in a material.

In gravimetric analysis, you determine the amount of a species by converting it to a product you can weigh. In volumetric analysis, you determine the amount of a species by titration.

Operational Skills Using solubility rules.
Writing net ionic equations. Deciding whether precipitation occurs. Classifying acids and bases as weak or strong. Writing an equation for a neutralization. Writing an equation for a reaction with gas formation. Assigning oxidation numbers. Balancing simple oxidation-reduction reactions. Calculating molarity from mass and volume. Using molarity as a conversion factor. Diluting a solution. Determining the amount of a substance by gravimetric analysis. Calculating the volume of reactant solution needed. Calculating the quantity of a substance by titration.

Dissociation Return to Lecture

Electrolytic Solutions
Negatively charged ions move towards the positive electrode and positively charged ions moves towards the negative electrode Return to Lecture

Conductivity Since there are no “free” ions on non-electrolytic solutions there is no flow of energy and the bulb does not lit. The “free” ions on electrolytic solutions completer the circuit and allow energy to flow lighting the bulb. Return to Lecture

Weak vs Strong Electrolytes
While both types of electrolytes conduct electricity the amount of “free” ions manifests itself by the brightness of the light emitted by the bulb. Return to Lecture

Water Solvation of Ions
Return to Lecture

Mixing KI (aq) and Pb(NO3)2 (aq) leading to precipitation of PbI2
Return to Lecture

Return to Lecture

Figure 4. 7: Household acids and bases
Figure 4.7: Household acids and bases. Photo courtesy of American Color. Return to Lecture

Figure 4.8: Preparation of red cabbage juice as an acid-base indicator.Photo courtesy of James Scherer. Return to Lecture

Neutralization Reaction
Neutralization reaction between Acetic Acid (Vinegar) and Baking Soda (Sodium Bicarbonate).

Making a Solution c) a) b)
a) Measure the mass of the compound to dissolve, b)make sure all solid makes it into the volumetric flask using the solvent, then dilute to the bottom of the neck, and c) add the last amount of solvent carefully making sure not to go past the volumetric mark. Return to Lecture

Titration c) a) b) Titration of an acid with a base. a) the flask contains acid and a few drops of phenolphthalein, which is colorless in acidic conditions, b) the endpoint has been reached (notice the faint pink color of the solution), finally in c), the solution is well beyond the end point since more base was added. Return to Lecture

Electron Exchange Electrons from the iron nail are transferred to the copper in solution, the solid copper plates the nail. Notice the color change in the solution, this is due to the lower amount of copper ions in solution. Return to Lecture

RedOx Summary Return to Lecture

Figure 4.13: A representation of an oxidation reduction reaction.
Return to Lecture

Figure 4.14: Oxidation reduction reaction of mercury (III) oxide into its elements. Photo courtesy of James Scherer. Return to Lecture

Figure 4.15: Oxidation reduction reaction of zinc metal and hydrochloric acid. Photo courtesy of American Color. Return to Lecture

Figure 4. 16: Oxidation reduction reaction of iron wool and oxygen
Figure 4.16: Oxidation reduction reaction of iron wool and oxygen. Photo courtesy of James Scherer. Return to Lecture

Calcium/Chlorine Reaction
Return to Lecture

Gravimetric Analysis A solution of potassium chromate is poured down a stirring rod into a solution containing an unknown amount of barium ion to precipitate Barium Chromate which is then filtered dried and weighed. Return to Lecture

Chemical Reactions Chapter 5 Dr. Victor Vilchiz.

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