Drake Glau Posted March 26, 2011 Report Share Posted March 26, 2011 (edited) Yes.It's just like a rate problem. If you go 20 miles in 34minutes than you traveled 20/34 miles per minute. For you it was mass/tablet so you take your (mass of acetylsalicylic acid/# of tablets) Edited March 26, 2011 by Drake Glau 1 Reply Link to post Share on other sites More sharing options...
IBavictim Posted March 28, 2011 Report Share Posted March 28, 2011 (edited) Hi, my Chem SL teacher never really explained the syllabus to us. She just said study it. Now that I'm looking over it, I have a tiny question! It has Topics 1-11 as Core topicsAnd 12-20 as "AHL" topicsSince I'm in SL, do I just go over Topics 1-11 (completely disregard 12-20 o.o) and then choose my 2 options?Edit: Oh and also, say I pick Option C, I would only need to study C1-C7 and not C8-C12? My teacher recommended studying everything but the syllabus says C8-C12 are extension material for HL only ^^" Edited March 28, 2011 by IBavictim Reply Link to post Share on other sites More sharing options...
dessskris Posted March 28, 2011 Report Share Posted March 28, 2011 Hi, my Chem SL teacher never really explained the syllabus to us. She just said study it. Now that I'm looking over it, I have a tiny question! It has Topics 1-11 as Core topicsAnd 12-20 as "AHL" topicsSince I'm in SL, do I just go over Topics 1-11 (completely disregard 12-20 o.o) and then choose my 2 options?Edit: Oh and also, say I pick Option C, I would only need to study C1-C7 and not C8-C12? My teacher recommended studying everything but the syllabus says C8-C12 are extension material for HL only ^^"I am in Chemistry SL too Just study the Core topics. AHL topics are meant for HL students only.So study topics 1-11 and option topics C1-C7.You can completely neglect topics 12-20 and option topics C8-C12 1 Reply Link to post Share on other sites More sharing options...
IBavictim Posted March 28, 2011 Report Share Posted March 28, 2011 Haha I was confused since she made us do some of the material from AHL. Thanks! Reply Link to post Share on other sites More sharing options...
Hinuku Posted March 30, 2011 Report Share Posted March 30, 2011 Hi, I'm confused about the rate determining step (kinetics). How do I know which one it is? I mean, I always thought; for example, that there if there are two steps then because the second step uses the product of the first one then the first one is the rate determining one as the second one can't proceed without it. Meanwhile, my teacher told me that it is not that simple and that sometimes the second step; although depending on the first one, can be the rate determining one. I need help as to recognising the RD step, thanks!Matt Reply Link to post Share on other sites More sharing options...
Daedalus Posted March 30, 2011 Report Share Posted March 30, 2011 Hi, I'm confused about the rate determining step (kinetics). How do I know which one it is? I mean, I always thought; for example, that there if there are two steps then because the second step uses the product of the first one then the first one is the rate determining one as the second one can't proceed without it. Meanwhile, my teacher told me that it is not that simple and that sometimes the second step; although depending on the first one, can be the rate determining one. I need help as to recognising the RD step, thanks!MattIt's always the slow step. The relationship between the two steps only influences the order of the reaction.Think about a massive factory, with thousands of shoes being produced every hour. If you can make 1 million shoelaces an hour but only 500,000 shoes, you're only going to make 500,000 shoes per hour, right? 1 Reply Link to post Share on other sites More sharing options...
IBavictim Posted April 1, 2011 Report Share Posted April 1, 2011 (edited) Hi! Does anyone have an easy way to remember how to name organic compounds with all the functional groups? I tend to mix the order up For example:```````CH3```````CN`````````|```````````` |CH3-CH-CH2-CH-CH3I saw that as 4-methylpentanenitrile .__. (I counted starting from the right)But the answer key says it's supposed to be 2,4-dimethylpentanenitrile (Counting from the left)Can someone explain to me why it's 2,4-dimethyl instead of just say, 2-methyl (counting from left)?And also, this is what I meant by mixing things up. Sometimes I don't know which one is 'more important' to start counting from (lol am I'm making sense? ) ><Thank you so much ! Edited April 1, 2011 by IBavictim Reply Link to post Share on other sites More sharing options...
kiwi.at.heart Posted April 1, 2011 Report Share Posted April 1, 2011 Hi! Does anyone have an easy way to remember how to name organic compounds with all the functional groups? I tend to mix the order up For example:```````CH3```````CN`````````|```````````` |CH3-CH-CH2-CH-CH3I saw that as 4-methylpentanenitrile .__. (I counted starting from the right)But the answer key says it's supposed to be 2,4-dimethylpentanenitrile (Counting from the left)Can someone explain to me why it's 2,4-dimethyl instead of just say, 2-methyl (counting from left)?And also, this is what I meant by mixing things up. Sometimes I don't know which one is 'more important' to start counting from (lol am I'm making sense? ) ><Thank you so much ! I'm probably not the best person to answer questions about organic chemistry but I'll try.When you look at the structure the first carbon you should count from is the one with the N. That is you first carbon in the chain, then you have 2 methyl groups coming off the chain at carbon 2 and carbon 4. Therefore it's 2,4-dimethylpentanenitrile.Hope that helps 2 Reply Link to post Share on other sites More sharing options...
Drake Glau Posted April 1, 2011 Report Share Posted April 1, 2011 (edited) Hi! Does anyone have an easy way to remember how to name organic compounds with all the functional groups? I tend to mix the order up For example:```````CH3```````CN`````````|```````````` |CH3-CH-CH2-CH-CH3I saw that as 4-methylpentanenitrile .__. (I counted starting from the right)But the answer key says it's supposed to be 2,4-dimethylpentanenitrile (Counting from the left)Can someone explain to me why it's 2,4-dimethyl instead of just say, 2-methyl (counting from left)?And also, this is what I meant by mixing things up. Sometimes I don't know which one is 'more important' to start counting from (lol am I'm making sense? ) ><Thank you so much ! FIRST thing you ever do for naming is find the longest chain of carbons. Doesn't matter how many turns you take or anything...find the longest chain possible. After that you find the functional group in the compound and number your carbons starting from there. After that you find the numbers and their groups and whatever. After that you put the functional groups in alphabetical order. If you have a methyl and an ethyl and maybe the methyl is on C2 and the ethyl is in C3, it doesn't matter that the methyl group comes first, ethyl starts with an e so it would be 3-ethyl-2-methylblahblahblah.And kiwia is right Edited April 1, 2011 by Drake Glau 1 Reply Link to post Share on other sites More sharing options...
IBavictim Posted April 1, 2011 Report Share Posted April 1, 2011 Thanks you guys! I appreciate it Naming the compounds is a pain in the behind but hopefully I'll get used to it ! Reply Link to post Share on other sites More sharing options...
adletaY Posted April 7, 2011 Report Share Posted April 7, 2011 I just did a test on Topic 1, it went pretty well, but there was one multiple choice question I was a little unsure about.Avogadro's constant is the same as:A. The number of molecules in 1 mole of solid IodineB The number of molecules in 1 mole of Chlorine gasC. The number of ions in 1 mole of Potassium BromideD. The number of protons in 1 mole of Helium gasI chose A because I think that solid Iodine is just I, so there should be 6.02x10^23 Iodines in 1 mole of solid Iodine. I am still unsure . . . can someone help me out? Reply Link to post Share on other sites More sharing options...
Drake Glau Posted April 7, 2011 Report Share Posted April 7, 2011 (edited) I'd choose B. Solid iodine is indeed just I, but it's just I...that's an atom...that'd be the number of ATOMS in solid iodine. Chlorine gas is diatomic and therefore Cl2 so avagadro's number would be the number of those diatomic molecules in one mole Also, just to explain the rest...C would actually be 2 moles since the KBr would be K+ and Br- and results in 2 moles instead of 1D is 2...yea... Edited April 7, 2011 by Drake Glau Reply Link to post Share on other sites More sharing options...
adletaY Posted April 12, 2011 Report Share Posted April 12, 2011 Ah, thanks, I think that I thought B was "The number of atoms in 1 mole of Chlorine gas," but I guess I was wrong. I should get my test back tomorrow, then I'll see. Reply Link to post Share on other sites More sharing options...
Hammerdown Posted April 17, 2011 Report Share Posted April 17, 2011 I have question:5 dm3 of carbon monoxide, CO (g), and 2 dm3 of oxygen, O2(g), at the same temperature and pressure are mixed together. Assuming complete reaction according to the equation given, what is the maximum volume of carbon dioxide, CO2(g), in dm3, that can be formed? 2CO(g)+O2(g)=2CO2(g)A. 3B. 4C. 5D. 7Thanks Reply Link to post Share on other sites More sharing options...
adletaY Posted April 17, 2011 Report Share Posted April 17, 2011 The limiting reagent is Oxygen gas.This is because, if you divide the volume of CO by 2 (the mole ratio), you get 2.5dm cubedHowever, dividing the volume of Oxygen gas by 1 (the mole ratio), gives 2dm cubedSo, there is less Oxygen gas, and so it is the limiting reagentTherefore, take this, multiply it by 2 to get the volume of Carbon Dioxide produced:2(2dm cubed) = 4dm cubed of Carbon DioxideWhich is B. 2 Reply Link to post Share on other sites More sharing options...
Keel Posted April 17, 2011 Report Share Posted April 17, 2011 The volume of all gases is proportional to the number of moles. Thus you have 5 units of CO and 2 units of O2. The ratio according to the equation is 2:1:2. To find the limiting reagent divide the ration with the units. CO = 2.5 and O2 = 2. Therefore O2 is the limiting reagent. Since 2 units of O2 will make 4 units of CO2, B is the answer. 1 Reply Link to post Share on other sites More sharing options...
Drake Glau Posted April 17, 2011 Report Share Posted April 17, 2011 (edited) Find your limiting reactant using the volume/mol ratio of 22.4. If you have 5dm3 of CO, thats 5/22.4=0.22mol and 2dm3 of O2 is 0.09mol. This makes O2 the limiting reactant and the mol:mol ratio of CO22 is 2:1 so that gives you 0.18mol of CO2. Use the volume per mole thingy again to get 0.18*22.4=4.032...or B Keel beat me, and adletaY beat me...I'm gettin' slow apparently lol Edited April 17, 2011 by Drake Glau 2 Reply Link to post Share on other sites More sharing options...
Hammerdown Posted April 19, 2011 Report Share Posted April 19, 2011 what is the maximum mass of iron that can be produced from the reduction of 80tonnes of iron(III) oxide (Mr = 160) based on this equations: Fe2O3+3CO -> 2Fe+3CO2A. 28 tonnesB. 56 tonnesC. 84 tonnesD. 112 tonnes Reply Link to post Share on other sites More sharing options...
Drake Glau Posted April 19, 2011 Report Share Posted April 19, 2011 (edited) 80tonnes=80,000kg (80,000,000g)80,000,000/160=500,0000mols of iron(III) oxideratio of 2:1 (product:reactant)500,000mols*2=1,000,0000mols of FeMrFe=55.8451,000,000*55.845=55,845,000grams1,000,000 grams per tonne55,845,000/1,000,000=55.845 or BShorter version:Convert tonnes to gramsGrams to molesFind your ratio in your reactionconvert moles back to gramsconvert grams to tonnes. Edited April 19, 2011 by Drake Glau Reply Link to post Share on other sites More sharing options...
Hammerdown Posted April 19, 2011 Report Share Posted April 19, 2011 80tonnes=160,000grams160,000/160=1000mols of iron(III) oxideratio of 2:1 (product:reactant)1000mols*2=2000mols of FeMrFe=55.8452000*55.845=111690grams2000 grams per tonne111690/2000=55.845 or BShorter version:Convert tonnes to gramsGrams to molesFind your ratio in your reactionconvert moles back to gramsconvert grams to tonnes. How exactly are you supposed to find your ratio ? Thanks Reply Link to post Share on other sites More sharing options...
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