Guest honeybabes_18 Posted April 7, 2004 Share Posted April 7, 2004 Calculate the mass of iron(III) sulfate required to prepare 150.0 mL of a 0.1235 M solution. Link to comment Share on other sites More sharing options...
Gampin Posted April 7, 2004 Share Posted April 7, 2004 (150e-3 L) * (0.1235 M) = 0.018525 mol FeSO4 0.01825 mol FeSO4 * 135.9082 g / 1 mol FeSO4 = 0.0001342818166968586148591475716697 g FeSO4 Link to comment Share on other sites More sharing options...
swansont Posted April 7, 2004 Share Posted April 7, 2004 (150e-3 L) * (0.1235 M) = 0.018525 mol FeSO4 0.01825 mol FeSO4 * 135.9082 g / 1 mol FeSO4 = 0.0001342818166968586148591475716697 g FeSO4 That's a rather egregious abuse of significant digits you've got there. Link to comment Share on other sites More sharing options...
wolfson Posted April 7, 2004 Share Posted April 7, 2004 Calculate the mass of iron(III) sulfate required to prepare 150.0 mL of a 0.1235 M solution. Number of moles = Volume.Molarity Volume in L or dm-3 Number of moles = (150/1000) x 0.1235M = 0.0185(25) 3.S.F. Mass = Molecular weight.Number of moles Mass in grams Molecular weight = Fe(55.845g) + S (32.066) + 04 (63.998) = 151.909g Thus: Mass = 151.909 x 0.0185 = 2.810 g. Wolfson Link to comment Share on other sites More sharing options...
Gampin Posted April 13, 2004 Share Posted April 13, 2004 um, i had some errors in there. Link to comment Share on other sites More sharing options...
wolfson Posted April 13, 2004 Share Posted April 13, 2004 um just a few What level of chem you at Gampin? Link to comment Share on other sites More sharing options...
chemistry Posted April 14, 2004 Share Posted April 14, 2004 It is inappropriate to use the molar mass of Fe on the periodic table when it asks for Fe(III) which has lost three electrons. -------------- Online help with college and high school chemistry -1 Link to comment Share on other sites More sharing options...
wolfson Posted April 14, 2004 Share Posted April 14, 2004 Thats just stupid. At his/her level of chemistry you do not do anything of the sort. Link to comment Share on other sites More sharing options...
chemistry Posted April 14, 2004 Share Posted April 14, 2004 The periodic table refers to atoms with 1:1 ratio of electrons to protons. Especially when we are dealing with high mole values this error will lead to a significant deviation from the true value. And yes, it is General Chemistry even high school chemistry where professors will use subtle problems as this to mark off the A students from the B...and thus your ignorance in chemistry. Link to comment Share on other sites More sharing options...
wolfson Posted April 14, 2004 Share Posted April 14, 2004 And yes, it is General Chemistry even high school chemistry where professors will use subtle problems as this to mark off the A students from the B. 1. I doubt this person is at A-Level grade, 2. It would confuse them, and three the AQA and EDE syllabus mentions nothing to that specification, that is the UK A-Level guides. and i was refering to your comment being stupid not you. Link to comment Share on other sites More sharing options...
wolfson Posted April 14, 2004 Share Posted April 14, 2004 I didnt mean to sound angry, all i am meaning is that a mass of an electron is 9.1093897e-28g, so unless i was aiming to have a value to 31d.p., but if I or anyone used a 32d.p. value then they would be marked down, as this makes no alteration to the mass 151.909g do you understand where i am coming from? Link to comment Share on other sites More sharing options...
chemistry Posted April 14, 2004 Share Posted April 14, 2004 The fact is that this problem also deals with knowledge of oxidation states and the periodic table. So it is significant for any grade level. As I said, the mass of the electron, if associated with a high mole value, will be very significant to the problem and will result in deviations from the real value. If your perspective is that of a step by step process in learning this material...I somewhat understand you. However, my opinion as well as all teachers, I am sure will require that the student understand the subtle aspect of this problem mainly since it deals with contents of other chapters. Link to comment Share on other sites More sharing options...
wolfson Posted April 14, 2004 Share Posted April 14, 2004 Im not saying they should not learn about OIL/RIG, but i am just saying that in the above calculations using the value of e- would be insignificant, i am not saying that they should not learn the concepts of OIL/RIG, most students (A-G grade) will know about OIL/RIG and the formations, but i am saying that nearly all students will not use the e- as part of there calculations. Link to comment Share on other sites More sharing options...
chemistry Posted April 14, 2004 Share Posted April 14, 2004 As I said and explained the value of the e- is not insignificant. How could you learn chemistry without realizing the significance of oxidation states; Fe is not the same as Fe(III). Despite the plausible existence of teachers who are ignorant enough to underemphasize this point, this subtle detail should be pointed out...as I have done. And I'm sure you would agree by now that pointing out this aspect of the problem was not in error, certainly not stupid. Link to comment Share on other sites More sharing options...
wolfson Posted April 14, 2004 Share Posted April 14, 2004 As I said and explained the value of the e- is not insignificant. Show me how it would significantly alter my calculation(s). How could you learn chemistry without realizing the significance of oxidation states; Fe is not the same as Fe(III). Did i say it was NO, i said the student(s) should and do learn the significant value, of oxidation and reduction. Despite the plausible existence of teachers who are ignorant enough to underemphasize this point, this subtle detail should be pointed out Well I teach first and second year students (part of a course), and they do well, and I can be sure i am not ignorant, some teachers though are slightly under achieving. And I'm sure you would agree by now that pointing out this aspect of the problem was not in error, certainly not stupid. I already said that i didnt mean to sound angry, and if you think i didnt know the term "oxidation" you are seriously mistaken. Link to comment Share on other sites More sharing options...
Guest honeybabes_18 Posted April 21, 2004 Share Posted April 21, 2004 I am really sorry for starting such an argument!!! Thankyou for your help wolfson... i got the question right with the explanation you gave me... and it was very easy to understand! Link to comment Share on other sites More sharing options...
YT2095 Posted April 21, 2004 Share Posted April 21, 2004 YOU have nothing to appologise for!!! and we`re glad you got your question right ) Link to comment Share on other sites More sharing options...
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