 All right youtubers, I haven't forgot about you. I'll go ahead and post a couple videos As reviewed for the final exam I'm gonna go through those Practice questions that we've gone through in class. It's be a great thing to watch as you're prepping for the final exam Again, these are similar questions to what you see on the final So that thought process that goes into it is really what it's all about So this is from the first practice test that I made up These are the questions that I wrote based strictly on what the study guide had to say Study guide says you have to be able to tell the difference in size between different atoms on the periodic table So they give you a set of atoms all in the same group or all in the same period You'd be able to figure out which one's the largest which one's the smallest The two elements we key in on are francium and And As you see in this illustration, francium is the largest atom on the periodic table So the closer something is to francy and the larger it's going to be Fluorine is the smallest atom on the periodic table so the closer to fluorine it is the smaller it's going to be So within a period of horizontal row The stuff that's over here on the left is closer to francium So it's the biggest The stuff that's over here closest to fluorine is going to be the smallest so the largest ones are the left smallest ones to the right within a group The one at the top is closest to fluorine. So it's the smallest The one closest to the bottom is closest to francium. So it's the largest those are the trends in atomic radius So you have magnesium phosphorus sulfur and sodium magnesium phosphorus sulfur And so the question asked which one's the largest so do you miss the one that's closest to francium? So it's the largest We have to note the trends in atomic radius as well As far as atomic radius is concerned. It's the same trend or ion size. It's concerned. It's the same trend Francium is going to be the largest it's down here It's the largest ion and fluorine is going to be the smallest In this case, they'll give you a set of elements. So either be all metals or all non metals They'll again be in the same period or the same group And you're going to say which one's the largest which one's the smallest based on its position on the periodic table Again, if there's three elements that are in the same group as in my question here Brilliant magnesium and calcium The one closest to the top is closest to fluorine. So it's the smallest The one further down as close as to francium. So it's the largest same exact trend you have with Atomic radius, it'll be the same thing if we had elements that were in the same period. So we were talking about phosphorus sulfur chlorine Phosphorus is closest to francium. So it's the largest chlorine is closest to fluorine. So it's the smallest same trend for both things Understand that all the elements in a period have the same number of energy levels. That is the period trend So if we're looking at potassium calcium Across the krypton all these elements here period four I'll have four energy levels. That's what they all have in common We look at lithium beryllium all the way over to neon Period two all those elements have two Energy levels the group trend is valence electrons group one has one group two has two group 13 has three 14 has four 15 has five 16 has six 17 has seven and 18 has eight the group trend is valence electrons the period trend is energy levels Isotope notation you got to know the number on the top is the mass and the number on the bottom is the atomic number When asked for the number of protons you just look at the number on the bottom you're looking at the atomic number the answer is 29 If you were ever asked for the number of neutrons, it's the top number minus the bottom number That's all I got to know about those those isotopes symbols They're atoms of elements that have a different number of neutrons again. That's not important You just got to know what these numbers are and how to interpret that on this one The way that most people define an atom is the smallest particle of an element that retains all the properties of that element That's the most commonly used definition of what an atom is Unfortunately, that's not the definition that they chose to use on the district level They chose to use the smallest unit of matter That retains the properties of matter and that really is a confusing definition I'm assuming by unit they mean a collection of pieces Because you know those each individual pieces protons neutrons electrons are smaller than an atom and even those are made up of smaller particles So one could consider a proton a unit because it's it's composed of two smaller particles still Again, it's a very confusing definition, but they are choosing this definition So we have to make sure that you know it smallest unit of matter that retains the properties of matter just I get it's a bad definition just know it orbital notation We got to remember that the arrows in the orbital notation represent electrons So the question we're to ask you what element is that all you got to do is count the arrows The arrows will tell you the atomic number to two four six eight ten twelve thirteen fourteen arrows there That means atomic number fourteen We look to our periodic table and that is so So again the number of arrows in the orbital notation that tells you the number of electrons in the atom That's going to be the same as the atomic number because we have to assume these things are neutral unless it tells us otherwise so That's your atomic number And a question like this where we have to figure out what's wrong with Orbital notations a few things to keep in mind When you do in p orbitals you have to put one arrow in each box first before you're allowed to double them up So when we look at this first one here, and this is incorrect There's two arrows in that box and these other two them been left empty Again, the rule is one arrow per box and then you can double them up So what we see here is more correct what we see here is what this one should look like with those two arrows separated You've got to watch the order of orbitals 1s 2s 2p 3s 3p 4s 3p and so on And make sure that they are in that order 1s 2s 2p 3s 3p 4s that one's correct 1s 2s 2p 3s 3p 4s that one's correct 1s 2s 2p 3s 3p 4s that one's correct 1s 2s 2p 3s 4s This one is not the order of orbitals bad in that one Another thing, and I didn't mention it up here. This is just a general electron configuration concept Is that you have to fill up levels before you move on to the next one. So we can't move on to 3p Until 3s has been filled completely. So that would be an error in this one So again, what's wrong with this one is this p orbital. You can't put those two together They would have to be separated The problem with this one is that this orbital is not filled before it went on to the next one The problem with this one is the order of orbitals here. They have 4s before 3p. These would have to be switched That's the only one that is correct of those four. It's the only one that fits all those criteria Lewis structures the dots are valence electrons So this particular element has five valence electrons and again the group trend is valence electrons So when you see five valence electrons, you know that this element belongs to group 15 Five valence electrons group 15 And we're looking for the member of period three in group 15 and that would be phosphorus this Lewis structure Has seven dots and again the dots are the valence electrons seven dots means seven valence electrons Seven valence electrons is telling us it's in group 17 on the periodic table again group one has one Group two has two that we script all the way over to group 13 and we drop the ones Group 13 has three 14 has four 15 has five 16 has six 17 has seven 18 has eight So seven valence electrons means group 17 Period four means row four and that is bromine I can make sure you know the dots are valence electrons and that The valence electrons are telling you what group it belongs to This is an important idea understanding that as electrons drop drop between energy levels they emit light and The further they have to drop the longer distance they drop the more energy that light has to have So if an electron drops a long distance it has to release a large amount of energy Which means it's going to be up at the high energy end of the electromagnetic spectrum over the visible spectrum Anyways, it's gonna be up at the violet end So that's what we see here We're going from level one or level seven all the way back down to level one again We're going a long long distance Long distance means a lot of energy a lot of energy means by the light If we're dropping a short distance the electron doesn't have to lose as much energy So what we would expect to see is something on the lower energy side of the visible spectrum and that would be red And remember roige biff red orange yellow green blue indigo violet It's in order from low energy to high energy So red is the lowest energy light violet is the highest energy light if it falls a short distance That's low energy. That's red if it falls a long distance. That's high energy. That's violet That's what you got to remember wish upon combinations Don't like to make a molecular compound and I've said this several times probably at least a dozen times over the past week Molecular compound means that you're dealing with a covalent substance covalent bonding And for covalent bonding you have to have two nonmetals So we look through this and look for the one with two nonmetals and that's light you're doing of roaming Molecular compound means covalent bonding covalent bonding means two nonmetals In order to ask for something ionic you'd be looking for something that has a metal in it metals do ionic bonding Which is the following is a covalent substance again same idea. You're looking for the one that's two nonmetals That would be C If it asked for which one was an ionic substance then we'd be looking for metals covalent all nonmetals ionic You got to have a metal Electron configurations when things ionized they're going to look like a noble gas and that's the important piece We got to recognize what noble gas that element's going to resemble When it makes its ion so metals will resemble the noble gas that come before it on the periodic table They lose electrons when they make their positive ions. So they drop in number Nonmetals will gain electrons when they form their negative ions when they gain electrons That means they'll resemble the noble gas that comes after it on the periodic table. So the number of electrons goes up So we're talking about oxygen in the first question here oxygen is atomic number eight That means oxygen has eight electrons When it makes its ion it has to gain two more electrons oxygen's a group 16 That means it has six bail as electrons already. It needs eight So it's going to de-gain two more So instead of having eight electrons, it'll have 10 Atomic number 10 is neon. That's what it's going to resemble. So we would pick The electron configuration that has 10 electrons in it Again Nonmetals will resemble the noble gas that comes after it. It's atomic number will go up basically Though the protons don't change the number of electrons will match that new atomic number So again oxygen starts off at eight electrons Because it's in group 16. It needs two more. So it ends up with 10 It resembles atomic number 10. It resembles neon What is done? For sodium, sodium is a metal. Metals have to lose their valence electrons to become stable Sodium normally has 11 It's a group one which means it has one valence electron It has to lose that one electron and what it does it'll only have 10 So again, it'll resemble Undoble gas with 10 electrons and again, that's neon See would be the answer here. So as I said, it's more about understanding what noble gas is going to look like Than anything else. That's how you find your answers and problems like this Novaclature remember when it's ionic it's got a metal in it When it's covalent it doesn't So this is an ionic substance that sodium in it And when you're dealing with your ionic substances never use prefixes, that's where they catch you all the time That's probably why this is on the third test now in a row that they've written A lot of mistakes made with those prefixes. If there's a metal in the formula, there's no prefix in the name For the ionic ones, you're just breaking to the positive and negative ion. The positive ion is sodium The negative ion is light-trite At O2 you do get that table of polyatomic ions on the final exam So look at it Make sure you're looking at the right thing because I've got light-tride, light-trite and light-trite in here You look on that table of polyatomic ions and O2 is light-trite So we know it's either this one or that one No Roman numeral in this because sodium is a predictable battle of synthesis. One So the answer is B For your covalence Well, that's where you use your prefixes. Tetra means four. So four bromine There's nothing in front of the carbon. So we assume it was supposed to be mono So this would be one carbon four bromine One carbon four bromine. The answer would be C Mono is one, di is two, tri is three, tetra is four Penta is five and I don't think you'd see anything beyond that Again, no prefixes if you have a metal Prefixes mean covalent Lewis structure question. What's the correct Lewis structure for HCL? I've given to this problem to you on a Quiz I've given this problem to you on a test. I think this problem was on the A third quarter exam as well All of these have HCL and at the questions, which one's right and which was right is the one that has the correct number of electrons around each atom Hydrogen is only allowed to have two electrons The dash counts as two electrons. So this is showing hydrogen with four. So we know that one's not right Again, the dash represents two electrons. That is showing hydrogen with four. So we know that's not right It's one again same problem Two four that's showing hydrogen with four electrons. That's not right That's the only one that shows the correct number of electrons on the hydrogen So that's got to be the right answer Hydrogen has to have two chlorine has to have eight That one only shows chlorine with two That one only shows chlorine with four That one shows it with eight, but again the hydrogen is the issue there That one shows the chlorine with eight. It's got to be two on the hydrogen eight on the chlorine answer is D Shapes bespert You gotta just know that Two atom molecules are always linear five atom molecules are always tetrahedral So those are the easy ones If you see one of these structures and you count two atoms in it You know it's linear you don't think anything more about it If you see one of these structures and you see five in there Tetrahedral, you don't have to think anything more about it It's only with the three and four atom molecules that we have to worry because there's two different shapes Three can be linear or bent Four can be trigonal planar or pure metal So again, it's a matter of trying to figure out what's going on with these pairs of electrons We're only looking at the middle atom When we do this The one that everything else is connected to and we're looking to see if we have a pair of dots on it This is a four atom molecule one two three four The middle atom has a pair of dots on it four atoms With a pair of dots would be pyramidal The answer to that one would be D Again, if they keep it simple on the final It'll either be a two atom or a five atom Two atom structures are linear five atom structures are tetrahedral They want to make it tricky to do three and four. I don't think they're going to make it tricky This is a polarity thing and um, this is a simple polar molecule They make these more complicated on the final then this is going to be a real pain to answer Here's what you got to know This is what works well in class when you're given electronegativities But there are no electronegativities on the reference sheet Which means you can't really use that as your reference So forget Learn this Hydrogen oxygen bonds are polar hydrogen fluorine bonds are polar hydrogen nitrogen bonds are polar So when you're looking at a structural formula if you see one of those bonds and the bond is polar And if you can separate the charge with a straight line put all the positives on one side all the negatives on the other Then it's a polar molecule and if it's polar it dissolves in water So let's take a look at the one we've got up here We've got a hydrogen fluorine bond and again hydrogen fluorine bonds are one of the three That are always polar bonds The hydrogen's always going to be the positive one of those bonds so it's positive that's negative You can split it with a straight line that is a polar molecule And because it's a polar molecule it will dissolve in a polar solvent like water Hydrogen carbon bonds are not polar I tell you that because there's a whole class of compounds called organic compounds and organic compounds have pretty complicated structures And there's a lot of carbons and hydrogens in those structures So what i'm telling you here is you can ignore all those carbon hydrogen bonds Because carbon hydrogen bonds are not polar bonds. We don't have to consider those in our polarity All we have to consider are the hydrogen oxygen hydrogen fluorine and hydrogen hydrogen bonds better in those molecules Molecular empirical formulas molecular formulas are for covalent substances. They are always covalent substances There can't be any metals in a molecular formula Empirical means reduced it's in its lowest terms that subscripts have been reduced It does not mean ionic even though those are the formulas we always use for ionic compounds Molecular means covalent empirical only means reduced. So this is asking which one is a molecular formula It's asking which one is covalent That means two non-metals the answer is b This one is asking which one's an empirical formula and again that is only asking you which one is reduced Two and six can be reduced. It's not a Two and two could be reduced. It's not b Three and one there's your reduced one that can't be reduced any further. So c is your empirical formula This one does happen to be ionic, but again, they don't have to be ionic our answer for the first question here That molecular formula c cl4 is also an empirical formula So empirical applies to both types of compounds ionic and covalent empirical only means reduced in its lowest terms Molecular means covalent Percent composition by mass. This is where we have to do the molar mass of the substance and then we have to plug it into the equation For percent part divided by whole times 100. The part is the mass of the element The whole is the molar mass Again, we multiply by 100. So we have nap04 The first thing we have to do is find the molar mass. There's one sodium times 23 this is 23 There's one phosphorus times 31 is 31 There's four oxygens times 16 is 64 And then we add all three of those together 23 plus 31 plus 64 is 118. That's the molar mass Now we're asked to do the percent mass for sodium So the number we use on top is sodiums. It's 23 over the molar mass 118 Times 100 and that's 19 percent. So the answer is c Again, we do the same thing here with the second one. We're doing methane this time ch4 The process starts with calculating the molar mass ch4 That's one carbon Times 12 is 12 And it has four hydrogens times one is four Add those together you get 60 It's asking for the percent composition of carbon So we use carbon's number on top. That's 12 divided by the molar mass 16 times 100 is 75 percent Which should be b Again the part divided by whole times 100 the part is whatever that element contributes. The whole is the molar mass Times 100 You need to know that the stronger the intermolecular forces the substance has the higher its boiling point is going to be I mean you don't even have to know this stuff hydrogen bondings the strongest dipole dipole attractions in the middle dispersion forces are the Weakest so hydrogen bonding would have the highest boiling point dispersion the lowest You don't even have to know that much Just know that the stronger The intermolecular force the higher the boiling point is going to be so because this is the strongest one It would have the highest boiling point the stronger the intermolecular force The higher the boiling point of the substance You need to know the temperature is a measurement of average kinetic energy that indicates how fast the particles are moving in matter So if something is hot that simply means the particles are moving very fast When something is cold that means the particles are moving very slow So when water is heated up Getting hotter and hotter the particles will be moving faster and faster If you were to cool water down the particles would move slower and slower simple as that State changes whether they're endothermic or exothermic depends on what states you're changing between here We're going from a liquid to a gas Solid liquid gas is in order From the lowest energy to the highest energy We are going from liquid to gas We're going from here to there We are going from low to high We're going from a lower energy state to a higher energy state And whatever you're going from a lower energy state to a higher energy state You're going to have to add energy to it And if you add energy to it, it is an endothermic phase change If we had gone the other direction from gas to liquid We'd be going from high to low. We'd have to remove energy from it and then it would be exothermic You've got to be able to interpret your heating graphs heating curves In particular, you have to pay attention to the state changes B is where it melts D is where it boils where the lines are flat. That's where the phase changes are happening The first phase change you come to is melting The second phase change you come to is boiling While a substance changes state, the temperature stays constant. That's why the line is flat So while it's melting, the temperature stays a constant negative 60 in this graph While it's boiling, the temperature stays a constant positive 60 in this graph Because the temperature is not changing The kinetic energy is not changing. Again, when we looked at it in class We talked a lot about potential energy in that point in the graph That's not the way they want you to look at it. They want you to understand the temperature is kinetic energy And since the kinetic energy or since the temperature is not changing At B and D, temperature is constant here, temperature is constant there You need to know that the kinetic energy is also constant at this place I know gas law. I've got gas law videos up there. I'm looking at the clock here and I'm thinking I want to get through all of these before This class comes in this morning. Again, ideal gas law, you're going to get the equation pv equals nrt You'll know it's an ideal gas law problem because you only have one of each variable There'll only be one pressure. There'll only be one temperature, etc So in this one, we only have one volume. We only have one pressure. We only have one temperature That's your indication that this is ideal gas law problem R will be given to you on the reference sheet so you don't have to memorize that either. It's just substitute and solve to make sure you know this Whenever you have leaders, you know that's B, wherever you have atmospheres, you know that's P, wherever you have Kelvin, you know it's T, wherever you have moles, you know it's n So identify your variables, take the time to do that, slow down to do that And then use your algebra skills to solve I got to have a whole video on the gas laws So go back and watch that if you want to review how to work the gas law problems You need to know how solubility is affected by temperature and pressure For temperature, it affects both the solid and the gas But it affects them in opposite ways For the solid, increasing the temperature generally increases the solubility. It's why you add sugar to T when it's hot You can dissolve more. The higher temperature means you have a higher solubility For gases, it's the other way around. For gases, the solubility decreases as the temperature goes up This is why you see a lot of dead fish around the lakes in the summertime As the water temperature goes up, the dissolved oxygen goes down and fish suffocate Pressure only affects gases So increasing or decreasing pressure would do nothing to a solid But it will change the gas. Increasing pressure will increase the solubility of the gas This is what they do with soda cans They put a high pressure of carbon dioxide in the can That increases the solubility of carbon dioxide and puts more of it in the liquid Then when you pop the can open the pressure drops So the solubility drops and all that carbon dioxide starts bubbling out. That's how they make fizzy drinks Again, the other gas laws just remember You'll know it's one of the other gas laws if there's duplicates of anything Like in this one here, I have two things that are in atmospheres. I have two pressures If I have two pressures, I know it's one of the other gas laws This is pressure that is volume. So I would use the equation that has pressures and volumes in it This one here has two temperatures, 290 kelvin, 225 kelvin I've got a duplicate on temperature. So I know it's one of the other gas laws. It's not the ideal gas law It's temperature and volume. So I picked the equation that has temperature and volume in it Watch your ones and twos read the questions carefully to figure that part out Again, what's most important is you keep the linked numbers together 0.75 liters at 290 kelvin. You know those have to go on the same side of the equal sign It doesn't really matter which side they're on. They just have to be on the same side of the equal sign 2.5 liters at 1.5 atmospheres means those are linked together They have to be on the same side of the equal sign. It really doesn't matter which side it is though Again, if you need more review on the gas laws go watch my gas law video As far as this is concerned it says in the study guide you're going to have pictures of balloons So I searched the internet and found some pictures of balloons This is its original size and these are our three options smaller same or larger If we were to cool down a balloon Decrease its temperature that would decrease its volume That's charles law So if we take this balloon and cool it down we would expect it to look like a We're expected to get smaller We were to heat that balloon up it would get bigger and it would look like see We also have to know the pressure thing to how the pressure wouldn't change it If we were to increase the pressure inside this balloon it would look like see it would get bigger We were to decrease the pressure in that balloon it would look like a The two concepts are really very much interrelated to one another It's really kind of a combined gas line if you have more than anything else But do make sure you understand that if you're going to change the temperature of a balloon Heating it up would make it bigger cooling it down would make it smaller If you were to change the pressure inside that balloon increasing the pressure would make it bigger decreasing the pressure To make it smaller they have kind of common sense stuff there, but it does say in the study guide there are pictures of balloons All right dissociation versus Solvation is the concept here and you got to understand this ionic compounds that dissociate And ionic compound means it has a metal in it. So when a question says which the following would dissociate water It's just asking you which one's ionic So you're looking for the one that has the metal in it and that would be see Like it dissociate means ionic Ionic means it's the one with the metal Well, there are any calculations and it does say in the study guide they're going to give you the molar mass So expect to get the grams of solute Expect to get the molar mass and expect to get the liters of solution Now that makes it simple All you got to do is take the grams of the solute to 55 grams Divide it by the molar mass 40 And then take that answer and divide it by the liters that you have So again when you're doing the molarity questions like this where they give you the mass of the solute Where they give you the molar mass where they give you the liters of solution Is simple We would do 55 the grams that they gave us divided by the molar mass of 40 That's 1.375 Take that number divided by 0.75 The liters of solution and we've got our answer 1.8 molar Again grams of solute divided by molar mass divided by liters of solution. It's all division all the way through Acids under the uranium definition is H something base is something OH So where it asks for The uranium acid is H something that would be It's got to be H and then some negative ion to be an acid Anything OH like this That's base It says in the study guide you have to be able to use particle diagrams to identify strong and weak acids And bases strong means dissociates completely Strong means it breaks down into ions completely So that's what the acid looks like The blue dot with the black dot attached to it and it's strong It's the one that has none of those left All of them have broken down all of them have separated into their component ions. That's what strong means All of these would be weak because you can see we still have acid left in all of those You got out of the properties of acids and bases and specifically these are the properties You got to know acids have a pH of less than 7 they take sour and litmus paper ends up red Blue turns red red stays red Bases have a pH greater than 7 they are bitter and the litmus paper ends up blue blue stays blue red turns blue So if I know the pH is 2 I know it's an acid Which means it's going to take sour and the blue litmus paper is going to turn red If I see that it's bitter I know that's a base and the pH is greater than 7 and I know the red litmus paper is going to turn blue You know those properties Neutralization is an acid reacting with the base something that starts with H reacting with something that ends with OH That's neutralization And when they neutralize they make a salt end of water That's obviously the water The leftover ions are the salts This is my acid H something this is my base something OH Conjugate acid base pairs They have the same negative ions they look a lot alike First thing to remember the acid has one more hydrogen than the base So we're looking at SO4 here So we know A and B are our only answer choices because they have to look like SO4 Okay, these are the only two that look like SO4 and they have SO4 in it The one with the hydrogen on it is going to be the acid that one's going to be the base So the answer is A or answer B This is the conjugate base to that Again, the base has the less hydrogen The acid has one more The conjugate acid for NH3 would have one more hydrogen in it. It'd be NH4 Again, the acid has one more hydrogen than the base does they look an awful lot alike. That's what you got to keep in mind You got to be able to identify those three reaction types and only those three reaction types Synthesis has no plus sign on the product side decomposition has no plus sign on the reactant side Single replacement has plus signs on both sides So no plus sign on the reactant side that is decomposition Plus signs on both sides. That is single replacement Should be some easy points to get there Got to be able to use a solubility table. Again, it's just important to recognize If you see an S on the solubility table, that does not mean solid S means soluble. That means it will dissolve in water And the state is AQ If you see an I on the solubility table, that means insoluble Insoluble. That means it does not dissolve in water. So your state is S I mean, that's the important thing to remember you find your positive ion You find your negative ion you see where they intercept and you see what letters there If it says S there the state is AQ If it says I there the state is solid a solid is called a precipitative. It's on the product side So don't be confused if a question asks you for precipitate They're just asking you which one would be solid On the product side So you're looking for the one that has an I in it when it's on the solubility table This was conservation of matter conservation of matter conservation of mass says that Matter can't be created or destroyed. The mass of the reactants has to be the same as the mass of the products That simply means you have to have the same thing on this side and this side So this is not conservation of matter because over here we have six of the white circles But we only have two on the product side. That's destruction of matter This one's not good because we have three blacks over here, but only two on that side Destroying matter again And in this one we have three white circles over here on the reactants side But four on the products ever creating matter there. So that doesn't work The answer is this one three white ones Three white ones three black ones three black ones Again in the study guide it says you have to be able to use a particle diagram to recognize conservation of matter I searched the internet. That's the best what I found for a multiple choice question. Uh, stoichiometry go watch my video on it Mole ratio problems. That's the key. Make sure you can do mole ratio problems Amagato's number is 6.02 times 10 to the 23rd. Make sure you memorize it. It is not on the reference sheet That is the number of atoms or molecules in one mole of a substance This important concept the higher the concentration of your reactants the faster the reaction will take place So if you have a lot of oxygen around the iron would rust faster If you had less oxygen around the iron would rust slower This might be vacuum seal stuff We vacuum seal stuff to reduce the concentration of oxygen and slow down the oxidation process As with this one would be if you increase the amount of oxygen that would increase the reaction rate That is an exothermic reaction. We know it's exothermic because it's downhill It's a downhill reaction. It's exothermic. You're going from high energy reactants to low energy products If it weren't uphill reaction, then it would be Endothermic. So again, look to see which direction you're going. If you're going downhill, it's exo. If you were going uphill, it's endo Energy kilojoules is on the reacted side when it's on the reacting side. It is an endothermic reaction If the energy had been on the product side, it would be exothermic And that is it Fortunately, there's only a few minutes of some physics here I'm going to do another video today during My second period planning going through the second practice test the one I made for the test banks that I have Same kind of idea. So you can sit there with your test to go back through it Look at questions answer them pause the video watch the video whatever you want to do with it Just so you have lots of resources available so you can base this final