Chem talk ch 4 sec 8

357-363

When speaking of change, chemists refer to the system and the surroundings. Together, the system and the surroundings make up the universe. You choose the system that you want to investigate and you can imagine drawing a dashed surface around the system, to separate it from the surroundings. When considering change you think about what the system is doing. When we stretched the rubber band we asked is it producing heat energy or releasing heat energy. If the system is an open system, energy can pass between the system and the surroundings. For example a teakettle heating on the stove is an open system. A closed system is a system that is isolated form the surroundings and heat can neither enter nor leave. This is very, very difficult to achieve. An attempt at a closed or isolated system is a thermos bottle. As we know a thermos bottle slow the movement of heat, but eventually the hot soup or cold beverage in the thermos bottle will exchange heat with the surroundings. When heat energy is released from the system, the surroundings gain that energy, while the system loses energy. If your hand is resting on the system, you feel heat energy coming from the system. When a system loses heat energy, there is a loss in the amount of enthalpy that the system contains. The change in enthalpy is negative. When heat energy is absorbed by a system, he surroundings must give that heat energy to the system. Energy must come from somewhere. The law of conservation of energy stats that energy cannot be created or destroyed. It can only be transferred from one location to another. If you hand is resting on the system, you feel heat energy leaving your hand and going to the system. When a system gains energy, there is an increase in the amount of energy the system posses. The change of enthalpy is positive. Whenever a change occurs, particles inside the system are rearranged. The new arrangement is either more or less disorganized. When the new arrangement is more disorganized the entropy has increased. The change in entropy is positive and the final entropy is a larger value than the initial entropy. Conversely, when the new arrangement is less spread out or more organized, the entropy has decreased. The entropy change is negative and the finial entropy is a lower value than the initial entropy. When materials change from gas to liquid, or liquid to solid the entropy decreases. Changes can occur either spontaneously or not. There are two factors that affect spontaneity are changes in enthalpy and changes in entropy. Exothermic changes drive a process toward spontaneity. This is because substances are produced that have lower energy than the reactants from which thy formed. Lower-energy states are favorable. Changes that result in an increase in entropy of the system also drive a process toward spontaneity. This is because nature tends to become more disorganized over time. If both factors change in the direction that favors spontaneity, the reaction will definitely be spontaneous. If neither factor changes in the direction that favors spontaneity, the reaction will definitely not be spontaneous. If only one change occurs in a favorable direction, the more dominant change will determine if the reaction is spontaneous. A third factor determines if a process will be spontaneous. Consider the freezing of water to form ice. If the water is left on the counter, freezing is not spontaneous. However, if the water is placed in the freezer. the process becomes spontaneous. The temperature at which a process occurs can affect whether or not a process will be spontaneous. The Gibbs free energy is a measurement that can be used to tell whether a change will occur spontaneously. If the change in Gibbs free energy is negative, the change will occur spontaneously at the given temp.

The change in Gibbs free energy can be determined using this equation:

ΔG= ΔH – TΔS (where the temp is measured in kelvins)

If ΔH and ΔS both have the same sign, ΔG could be positive or negative depending on whether ΔS or ΔH is more influential in determining the sign of ΔG. If ΔG is positive the reaction is not spontaneous at room temp. Polymers are molecules made of long strings of monomers that are attached to each other. This structure causes materials that are made of polymers to exhibit some unusual behaviors. When we heated the rubber band with the hair dyer we encountered this by the rubber band getting shorter or contracting. We need to compare the enthalpy and entropy of the two states of the rubber band. When the rubber band is in a stretched state, the entropy (disorder) is low because the molecules are pulled relatively straight and lined up. The enthalpy is also low when the rubber band is in a stretched state because the aligned molecules are able to experience attractions to each other. Molecules exhibit a smilier relationship between distance and energy. Molecules experience relatively weak attractions for each other when they are close together. This means when a molecule us attracted to another it is at a lower energy (enthalpy) state. When the rubber band is in a contracted state, the entropy (disorder) is high because the molecules are tangled around each other. The enthalpy is also high because the molecules are father apart from other molecules. When a molecule does not have other nearby molecules to be attracted to, the molecule is at a higher energy (enthalpy). The enthalpy factor favors the rubber band becoming stretched. Nature favors results that end with high enthalpy. At room temp the change in entropy dominates the change in enthalpy because a rubber band does not stretch at room temp by itself. The rubber band stretched when you decreased its temperature by cooling it with ice. This means that at a lower temp the stretched state is favored. The change in enthalpy drives the rubber band toward a stretched state. Therefore, at a lower temp the enthalpy factor becomes dominant over the entropy factor. Because the rubber band is stretched when cooled with ice and is contracted at room temp, increasing temp causes the rubber band to contract. As the temp increases the change in entropy makes the contraction of the rubber band more and more spontaneous. Therefore, the rubber band contracts more than it does at room temp. Polymers are probably the most versatile substances that technology has produced. They can change in what they feel like and scientist can change their properties. One of the most exciting fields in which polymers are used is medicine. A polymer called a thermoplastic polymer is used to stick the working parts of the mechanical heart to the heart itself. Thermoplastics are usually polyesters or polymers in which the repeating monomer forms an ester linkage between an organic acid and an alcohol. Polyethylene terephthalate is a copolymer of terephthalic acid and ethylene glycol connected by the ester functional group. Properties of polymers are such that they can be so sturdy that they can be used to construct cars and buildings, or so elastic that they can be used to make trampolines and playground balls. The fields of polymer chemistry and materials science are exciting and employ many chemists.

Chem talk ch 4 sec 7

345-349

In this section we explore a chemical reaction that continues to occur on its own once it begins. This reaction is called spontaneous. In a case of a reaction that produces heat energy, controlling the speed of the reaction will let you control how quickly heat is produced. For chemists and engineers to be able to control chemical reactions, they must be able to predict when reactions can occur spontaneously, and also what can be done to speed up or slow down reactions. One set of theories called thermodynamics is used to answer the question “Can a reaction occur spontaneously?” A second set of theories called kinetics is used to answer the question “How fast can a reaction occur?” Together, thermodynamics and kinetics help chemists and engineers to design reaction and processes that impact everyone’s lives. There are two factors that determine if a change can occur spontaneously. The first factor that affects spontaneity is if the changes gives off heat energy when it occurs or absorbs heat energy when it occurs. The second factor that affects spontaneity is if the change results in particles becoming more disordered or less disordered. Two commonsense rules apply to these two questions. First, lower energies are more stable than higher energies. So, in the same way that a ball tends to roll downhill, energy changes in chemical reactions tend to occur in ways that allow the substances to end up with lower energy. This means that changes that release energy tend to be favored. Second, everything tends to become more disorganized over time, so the changes in which particles become mire disordered are favored over those that make particles become more ordered. The two factors that affect spontaneity can work together. If a change both releases energy and results in an increase in disorder, the change is definitely spontaneous, the change is definitely not spontaneous. However, if one factor is favorable and the order is not, whichever is the stronger tendency controls whether the change is spontaneous. In our investigation we explore change that was spontaneous. Heat energy was given off as the system went from a higher energy to a lower one. This means at least one of the two factors affecting spontaneity is favorable for this reaction. When we had the magnesium in the water some main points that happened are:

when chemical reactions happen, bonds in the reactants break, and new bonds form to make products.
Breaking bonds requires energy input so bond-breaking is an endothermic change.
Forming bonds releases energy, so bond-forming is an exothermic change
The overall or net change can be endothermic or exothermic, depending on whether the total energy input or the total energy output is greater
In the chemical reaction between the Mg and the water, the total energy input required to break the bonds in the reactants is +572 kJ. Endothermic changes are positive because they are gaining energy. When the new bonds form in the products the total energy output is -925 kJ. exothermic changes are negative because they lose energy. The overall or net change is more exothermic than endothermic because more energy is produces than absorbed.

One way to show enthalpy change is to draw an energy diagram. It shows the progress of the reaction from reactants to products along the horizontal axis. Along the vertical axis, the diagram shows the change in potential energy that occur as substances progress from reactants to products. An energy diagram provide the following two important pieces of information: 

Endothermic or exothermic: The relative locations of the reactant energy and product energy indicate whether the overall enthalpy change is endothermic or exothermic. If there starting point is higher than the ending point then the system releases heat energy to the surroundings (an exothermic change), and overall enthalpy change is negative. If there starting point is lower than the ending point then the system releases heat energy to the surroundings (an endothermic change), and overall enthalpy change is positive.

Activation energy: Regardless of whether the change is endothermic or exothermic, bonds must always be broken in the reactants before new bonds can form in the products. Therefore, some initial amount of energy must be supplied to the system in order for the reaction to begin. This is represented as an activation barrier, or an initial “bump” in the curve, to get from reactants to products. The height of this bump. measured from the reactant energy is called the activation energy and it is always positive. The intermediate state, between reactants and products, at the top of the barrie is called the activated complex.

In our investigation we observed Mg with water and compared that reaction with the reaction of Mg and NaCl and water , we could se that the reactions were very slow. Little heat was generated, although the salt solution reacted slightly faster than water alone. Tiny bubbles of hydrogen slowly formed. When we compared the reaction in a salt solution with the reaction of Mg, salt water, and powered iron, the difference was very dramatic. After a few minutes, the sample containing iron produced much more heat and bubbled vigorously. This combination could indeed be used to heat a metal in an outdoors setting. A comparison of the last two samples tested was simply a comparison of the same reaction and the same components, but the size of the Mg particles was different. Test tube D contained a single larger piece of Mg strip while test tube C used granulated Mg. Granulated Mg contains much more surface area than the single piece and the reaction proceeds much faster. This is because reactions can take place only when the reactants collide. When the reactant is a solid, these collisions can only occur on the surface. More surface area= faster reaction. The iron is a key component for speeding up the reaction and it must not only be present, but physically imbedded in the Mg in order for it to function. This type of heater according to the scientists and engineers who developed this MRE heater, the iron is a catalyst for the following reaction:

Mg (s) + 2H2O(l) ^Fe> Mg (OH)2(aq) + H2(g) + heat

A catalyst is a substance that speeds up a chemical reaction without being used up itself. A catalyst works by providing a lower energy alternative pathway for the reaction to take. In essence, it provides a lower activation energy. As a result more starting materials at a given temp have enough energy to get over the energy barrier. This speeds up the reaction and generates heat quicker. As the temp increases, the reaction speeds up even more. However, the NaCl also plays a role in the reaction by being an electrolyte. When dissolved in water, the slat provides a pathway for the electrons to move from the Mg, which is then oxidized, to the H atoms that are reduced. The oxygen in water remains in the same oxidation state as it becomes a part of the hydroxide ion.

chem to go ch 4 sec 6

1. KF and Na2SO4 would conduct electricity because they are ionic bonds.
2. Water does not conduct electricity, but it is an electrical conductor, so it would not be a good idea to mix water and electrical appliances. It would not be safe. Our bodies are also electrical conductors, so thats why we get shocked when all of this is mixed.
3. Probably.
4. Anything lower than zinc on the chart because they will all oxidize with copper and will have a higher voltage in doing s0.
5. Voltage would decrease – Voltage would decrease – Voltage would decrease – Probably stay the same, but eventually decrease.
6. The conductivity decreases.
7. (C) Au ^3+ + 3e- –> Au
8. The numbers lost is always equal to the number gained

Chem talk ch 4 sec 6

page 336-338

Substances that dissolve in water to make solutions that conduct electricity are called electrolytes. In this invention we used a conductivity tester to determine if a solution conducted electricity. For any solution to be able to conduct electricity, it must contain charged particles that are able to move. Al the solutions we tested were made of substances that were dissolved in distilled water. For a solution to conduct electricity, there are two conditions that must be met. Charged particles must be present and the charged particles must be able to move around. Some compounds dissolve in water to form charged particles called ions. For example NaCl crystals dissolve in water, the sodium ions (Na+) and the chloride ions (Cl-) separate from the crystal and are surrounded by water molecules. Since the ions are surrounded by water, they can move about in the water. Since there are charged particles that can move, a solution of sodium chloride is able to conduct electricity. Molecular compounds do not break up into ions when they dissolve. For example sugar remains as sugar molecules when it dissolves, it does not separate. Since molecules do not form charged particles in solution, solutions made of molecules dissolved in water do not conduct electricity. Molecules that do not form ions in solution are non-electrolytes. A battery, or electrochemical cell, is composed of two half cells. The half cell where oxidation takes place is called the anode. The other half cell, where reduction takes place, is called the cathode. The anode and the cathode can not exist without the other because whenever an oxidation reaction takes place, there must simultaneously be a reduction reaction. During our investigation, electrons are produced by the oxidation of zinc metal at the anode. While the battery is operating, the zinc metal electrode is slowly undergoing a reaction. Neutral zinc metal atoms make two products according to the equation. Zinc ions and electrons are produced at the anode. The zinc ions enter the zinc nitrate solution while the electrons travel through the wire. Eventually, the electrons reach the copper metal electrode where reduction takes place. When the electrons reach the copper electrode they enter the cathode. In this half-reaction, copper ions from the solution combine with electrons to make neutral copper metal atoms. So, the copper metal elected increases in mass because copper metal us slowly attaching to it. This was the reddish brown sludge we observed forming on the copper electrode. The blue color of the copper (II) nitrate solution will diminish as the copper ions are used up. The copper ions are not the only ions in the solution. The solution was originally prepared by dissolving Cu(NO3)2 crystals in water. When this compound dissolves in water, Cu2+ ions and NO3- ions are both surrounded by water molecules. As the positively charged nitrate (NO3-) ions get “pushed out” of the region, because the solution myst remain neutral. The only place for the NO3- ions to go through the salt bridge. After passing through the bridge, they enter the zinc half cell. The Zn2+ ions are being created at the anode as the battery operates. Because of this, there is a need for additional negative ions to balance the increasing positive charge from the zinc ions. One important thing to know is that the electricity only runs spontaneously in one direction in a battery because of the relative activities of the two metal electrodes used in the half-reactions.

Chem Talk ch 4 sec 5

page 326-329

In this investigation we examined the colors that make up visible light and used LEDs to explore a glow-in-the-dark star. Light is a form of energy known as electromagnetic radiation. Electromagnetic radiation includes X-rays, ultraviolets (UV) rays, microwaves, and radio waves in addition to visible light. The electromagnetic spectrum (a list of electromagnetic radiation in order of wavelength) is illustrated in the diagram. Light can be characterized by its wavelength and its energy. The wavelength of light is the distance between two corresponding points of a wave. Wavelength is measured in nanometers (nm), which is one-billionth of a meter or 1 x 10^-9 m. Gamma rays have the shortest wavelength and radio waves have the longest wavelength. The wavelength of radio waves is close to 10^9 nm or 1m. Gamma rays have a wavelength of less than 0.1 nm which is close to the size of an atom. All weaves of light travel at the same speed in the vacuum. This is called the speed of light. You can relate the wavelength to another property of light called, frequency. The frequency of light is related to the wavelength of light by the following expression: λν=c where c=speed of light = 3 x 10^8 m/s

f= frequency in waves per second

λ= wavelength in meters

We measured the wavelengths of the light using the unit of nanometers. We then have to convert the wavelength to meters is we use the value of the speed of light in meters per second. Waves with long wavelengths have relatively low frequencies. Waves with short wavelengths have relatively high frequencies. This relationship is expressed as “frequency and wavelength are inversely related.” This means that as the wavelength increases the frequency decreases. The energy of light is related to the frequency (and wavelength) of the light. The mathematic equation that relates the two is:

E = h x f

where E= energy measured in joules

h= Planck’s constant = 6.63 x 10^-34 J.s

f= frequency in s^-1

Light that has a long wavelength has less energy than light that has a short wavelength. The wavelengths of visible light range from 700nm for red to 400nm for violet. As the wavelength of light becomes shorted, the energy of the light increases. The red light had less energy than the blue which is why the red LED had no effect on the glow in the dark star. The wavelength determines if the light has enough energy to interact with electrons in an atom. An atom consists of protons, neutrons, and electrons. The protons and neutrons are located in the nucleus and the electrons exist outside the nucleus in certain allowable states that are called energy levels. The outermost electrons are called the valence electrons which are the electrons that take part in chemical reactions. The main idea behind spectroscopy is that energy is conserved. When an electron absorbs energy it can move from a lower energy level to a higher one. However, the energy that the electron absorbs must be equal to the energy difference between the two levels. If an electron does not receive enough energy it will not be promoted to a higher energy level. This happened in part B when the glow in the dark star was irradiated with red light. The red light did not have enough energy to have any effect on the glow in the dark star. When an electron absorbs enough energy to be promoted to a higher state, that state is called an excited state, to distinguish it from the ground state where the electron began. The energy that an electron absorbs may come from lots of sources of energy, including heat energy, collisions between particles in the material, chemical reactions visible light, or even other forms of electromagnetic radiation. The electron, however, cannot remain in the excited state forever. It will eventually fall to a lower energy state and gives up energy in the process. A common process by which light is emitted from atoms or molecules is fluorescence. The process of fluorescence is when light provides energy to the electron and electrons are promoted to a higher state. Then the electron drops down to a lower state and emits light as it falls. When the LEDs gave off light they did this by the fluorescence method, but when the glow in the dark star gave off light it did it by a different method called phosphorescence. In this method there is another excited state in between where the electron is first promoted and the ground state. Depending on conditions such as temperature, the electron can temporality get stuck in this intermediate state. As a result the emission of light in some cases of phosphorescence is delayed over a period of time, ranging from seconds to hours. This delayed of emission of light causes the glow in the dark star to continue to glow long after the source of excitation, in this case the UV LED or the blue LED, is removed. In our investigation, a glow in the dark star was irradiated with red, orange, yellow, green, blue, UV, and white light. Red, orange, yellow, and green LEDS had no effect on the star because they did not have enough energy to move electrons from their ground state to an excited state. However, the blue and UV LEDs were used the electrons were excited and the star emitted a yellow-green light. The white LED also caused the star to glow because a small portion of the light that the white LED emits is in the blue portion of the visible spectrum.

chem talk ch 4 sec 4

page 316-318

Metals are shiny. They can also conduct electricity, so they are used in electrical circuits. They conduct heat, so they are used in cookware. Since most metals can withstand high temperatures, they are used to build strong structures. They are malleable and are pounded into different shapes with a hammer, and can be made into nails, flat surfaces, or boxes. Most metals don’t occur commonly as pure metals. The majority of metals are more reactive than hydrogen, and are most commonly found in nature in their ionic forms, as positive charged ions involved in solid crystals or dissolved water. It is possible to make another element out of a different element because the identity of an atom is specified by how many protons are in its nucleus (the meaning of the atomic number on the periodic table). When an atom interacts with another, only the arrangement of electrons is changed. While experimenting with this chemist figured that some metals react more easily with most metal ion solutions than other metals do. They developed the activity series from their observations.The reactions that can occur between neutral metal atoms, such as Zn, and metal ions, such as Cu2+, are part of a special class of reactions called oxidation-reduction reactions )”redox” for short). Oxidation is defined as giving up electrons, so all of the equations you listed in the activity series represented oxidations. Zinc metals oxidizes: Zn–> Zn2+ + 2e-. Reduction is receiving electrons. An oxidation equation turned backwards represents a reduction.

Copper ions reduce: Cu2+ + 2e- –> Cu

In our investigation when an oxidation happens, a reduction also occurs. Electrons that are given up have to be received by something. So, oxidation changes and reduction changes are often called half-reactions because you need both halves for a reaction to occur. You use half reactions to balance redox equations by making sure the number of electrons lost is equal to the number of electrons gained. Since the same number of electrons are lost as are gained, the half reactions can be added as they are; and the electrons will cancel. These are helpful to see which one is more reactive and which is less for our investigation. Hydrogen is included in the metals activity series because these acids are simple and convenient reagents which can be quickly established where an unknown metal stands in the series.

problem

using 0.02L of 20M HA and g of CaCO3. how much would it take to blow up a perfectly spherical  balloon?

CaCO3(s)+HCl(aq)–>CaO+CaCl2+CO2(g)

grams CaCO3(A)–>moles CaCO3(D)—> moles HCl(?)–>liters HCl

3g of CaCO3*100gCaCO3/1 mole CaCO3*2 moles HCL/ 1 moles CaCO3*I liter HCl/ 2 moles HCl

=.03 L HCl

chem to go ch 4 sec 3

1

a. CO2

b. The seltzer water with heat

c. The reaction would not be complete if both materials were not there in the beginning.

d. Yes, it does matter how much of the starting material was available.

2. NaHCO3 + HC2H3O2 —> NaC2H3O2 +H2O + CO2

(23+1+12) + (1+24+3+32) —> (23+24+3+32) + (2+16) + (12+32)

144 —> 144

3.

a. 12 grams C/1 mole Al

b. 27 grams Al/ 1 mole Al

c. 17 grams NH3/ 1 mole NH3

d. 100 grams CaCO3/ 1 mole CaCO3

e. 242 grams NaAl(SO4)2/ 1 mole NaAl(SO4)2

4.

a. 0.67 moles

b. 13.5g

c. 48.28 g

d. 24.2 moles

5.

a. They are equal because there are 2 K’s on each side, 2 Cl’s on each side and 6 O’s on each side.

b. 2KClO3 –> 2KCl +3O2

2(40+35+(16*3)) –> 2(40+35) + 3(16*2)

246–> 246

6.

a. 162.12 moles CO2; 7.46 moles H2; 14.92 moles He

b. The mass of the H2 balloon is 0.48 grams

c. The mass of He balloon is 0.25 grams

 

chem talk ch 4 sec 3

A mole is a counting word used to count very large quantities of very small objects (mainly atoms and molecules). 1 mole= 6.022 * 10^23. Three moles of something is three times as much as one mole. One mole of a single kind of atom or molecule has a mass equal to its atomic or molecular mass expressed in grams. One mole of oxygen atoms has a mass of 16.00g. This is called molar mass of oxygen atoms. An oxygen molecule (O2) is made of two oxygen atoms. One mole of an oxygen molecule has a mass go 32.00g. This is the molar mass of an oxygen molecule. To find the mass of a compound, the masses of each atom in the compound are added together.Another section that w have learned in this section is that one mole of almost any gas at standard temperature and pressure (STP) will occupy the same volume (22.4L). Standard pressure (1 atm or 760 mm Hg) is close to the pressure under which you live. When the temperature of a gas increases, the volume occupied by the gas increases. So, while one mole of a gas at standard conditions will occupy 22.4L, one mole of gas at room temperature will be a bit larger.In our investigation we calculated the volume of carbon dioxide gas needed to blow up a balloon. We also calculated the number of moles of the reactants needed. This kind of computation is called stoichiometry. The heart of stoichiometric calculation involves calculating the number of moles of one chemical in a reaction based on the number of moles of one of the other chemicals in the balanced chemical equation. The coefficients in the balanced equations set the proportions. These proportions relate the number of moles of any reactant or product in the reaction to the other reactant of product. These ratios or proportions never change, because compounds have fixed formulas or proportions. If you use three times as much of a starting material, that will be enough to make three times as much product. You can use equivalent-measure dominos to do these calculations.Although the amount of a substance generated or consumed during a chemical reaction is based on the number of moles of particle that interact, there is no equipment that can measure moles directly. Therefore moles must be converted into something you can actually measure. Two measurements that are easy to make in the lab are mass of a solid or liquid and volume of a gas. Using the stoichiometry method, you can convert a known mass of any chemical (or the volume of a gas at STP) into moles, and then convert your answer in moles back into grams (or liters of a gas at STP).To solve a stoichiometry problem, you have to figure out what measurement you are beginning with and what measurement you want to end with before you do the problem. Then you look at ways you can covert, using dominoes, between one unit and another. There are three kinds of dominoes at our disposal.You can use the molar mass of a substance. The domino will include one mole of the substance and its molar mass. To use this domino, you will need the periodic table.You can use the coefficients from a balanced chemical equation. When using this domino, both units will be moles.You can use the volume (amount of space) that one mole of gas takes up. This will always be the same domino: 1 mol of gas at STP is equivalent to 22.4 L of gas. In all of these calculations, the units multiply and divide (canceling each other out) to give the proper units for the answer. This is called dimensional analysis. It indicates that you method of solution is reasonable. If the procedure you followed to produce an answer was incorrect, it would be unlikely to yield the proper units. One way to think about the mole ratio is that you put the chemical and measure (moles, grams or liters) you’re converting from on the bottom of the ratio so that it will cancel the chemical and measure on the top of the preceding domino. This leaves only the units from the top half of the ratio (domino), which come from the chemical and measure you are converting to.When a reaction is carried out and the product is recovered and measured, it is common to find that less than 100 precent of the expected product is found. That is why scientist commonly report a precent yield for a reaction. The concept of percent yield has the following two purposes:Scientists attempting to reproduce the original work will know how much product they can expect to recover. If a company needs 100 kg of a certain product, but can only expect a 50 precent yield of the product from the reaction, they know they have to use twice the mass of reactant to obtain 100 kg of the product.

Chem to go ch 4 sec 1

1.

a. exothermic because the tablet is releasing energy while the water is absorbing it

b. exothermic because when water goes from a gas to a liquid it releases energy

c. endothermic because the oxidation is the lost of energy and the copper is gaining the energy

2.

a. the disorder is increased (disordered-ish) because the tablet is dissolving in the water making it aqueous

b. the order is increased (ordered-ish) because when you go from a gas to a liquid the order is increased.

c. not possible to tell

3.

a. reactants: 4Fe(s), 3O2 and,2KCIO3(s). The products are 2Fe2O3 (S), 2KCl(s) and 3O2 (g).

b. the first one decreases in disorder because it is a solid and a gas going into a solid. It is losing disorder and gaining order. The second one increases in disorder because you are going from a solid to a solid and a gas increasing in the disorder.

4. c

5. d

6. d