  # SNF

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Female
• Exams
May 2017
• Country
Rwanda
1. the question was ---- log a (a^2)-4 log (1/a). And it said simplify. for my final answer I got log a (a^2/1/4)^4. It is correct? please correct me if I'm wrong. Do you think there is more simplification to this?
2. Hello there, I have finished my o/levels in Cambridge and is doing IB, but its only been a few months since I started IB. Our school is having a lot of university visits and this had made me think more deeply on what I want to do. I love biology specially, and something had come up that says that they give scholarships for those students who had completed IGCSE to do biomedical engineering in UK. I'm not really a math and physics person even though I love chemistry and biology. Do you think biomedical engineering is the right way to go? what are your opinions if you were in my shoes? thank you.
3. Just curious, is this Math SL? I don't know. I'm doing math SL (its only been a few weeks now). the teacher just read the question out of his own book for practice
4. The tangent to the circle (x+4)^2+(y-1)^2=242 at )7,-10) meets the y axis at S and the x axsis at T. 1) Find the coordinates of S and T 2) Hence, find the area of OST, where O is the origin
5. So what your saying is that universities will not accept me with only an IGCSE qualification? Out of curiosity why did you think IGCSE would get you into uni? It's like clearly only a grade 9 and 10 course. Several friends of mine got into uni with just their IGCSE but most of them went into a business or IT degree. I asked the carrier guidance in our school and she told me that anyone can go into uni with igcse but it depends on the course that you would want to pursue. I have done some research and there are universities that accept only igcse but we have to do a six month foundation.
6. So what your saying is that universities will not accept me with only an IGCSE qualification?
7. Hello there, I had been doing IB but it seems like I'm going to switch schools, more specifically switch to a different country. I did IGCSE (Cambridge Qualification) and I have a GPA of 3.70/4.00. I'd like to know if there are any universities that would accept me for my IGCSE. I am doing SATs, ACTs and APTs at the moment. I want to major in biology in uni. Pls help out. Thank you
8. Khan Academy is a great website when it comes to any subject. Just google it.
9. No, it shouldn't. The theoretical yield is the maximum amount of product that can be formed if all of the reactant reacts whereas the experimental yield is how much actually reacts. The percentage yield would be calculated by: (experimental (actual) yield/theoretical yield) * 100 Thank you. the experiment yield was given as 28g.. and the theoretical yield is 10g. therefore when u divide and multiply by a 100 you get 280%. I know it cannot be possible. No you didn't get 280%. The reason is because the equation that you wrote wasn't balanced. The right equations must be: 4FeS2 + 11O2 ---> 2FeO3 + 8SO2 2SO2 + O2 ---> 2SO3 First, let's consider the first equation. Number of moles of FeS2 is 30/(56+32*2) = 30 / 120 = 0.25 moles. Since the ratio of the coefficient of FeS2 to the coefficient of SO2 is 4:8 = 1:2 --> this means that the number of moles of SO2 yielded is 0.25 * 2 = 0.5 moles Now, all SO2 yielded in the first equation will react with the excess oxygen to yield SO3 in the second equation, with the ratio of SO2:SO3 = 2:2 = 1:1 --> this means that the number of moles of SO3 yielded is 0.5 moles. The mass of SO3 corresponding to 0.5 moles is 0.5 * (32+16*3) = 0.5 * 80 = 40g. Since you got 28g for your experiment, the percentage yield is 28 / 40 * 100 = 70%
10. No, it shouldn't. The theoretical yield is the maximum amount of product that can be formed if all of the reactant reacts whereas the experimental yield is how much actually reacts. The percentage yield would be calculated by: (experimental (actual) yield/theoretical yield) * 100 the experiment yield was given as 28g.. and the theoretical yield is 10g. therefore when u divide and multiply by a 100 you get 280%. I know it cannot be possible.
11. thank you. I understand so much better. I have a question. can the percentage ever be more than 100? because when I calculated the percentage yield with a given experimental yield I get 280%.
12. sulfur trioxide SO3 can be produced in the following two step reaction; 4FeS2+11O2--->2FeO3+8SO2+2SO2+O2--->2SO3 30.0g of iron disulfide FeS2 reacts in the presence of excess oxygen to completion. a)Calculate the theoretical yield in g of sulfur trioxide
13. 1. Acetylsalicylic acid, also known as aspirin, C9H8O4, is synthesized by reacting salicylic acid, C7H6O3, with acetic anhydride, C4H6O3. C7H6O3+C4H6O3=C9H8O4+C2H4O2. a) Calculate the theoretical yield, in g, of aspirin when 3.0 g of salicylic acid is reacted with 4.0 g of acetic anhydride.
14. Hello there, Our chem teacher told us to solve this question; An organic compound contains 58.8% Carbon, 9.8% Hydorgen and 31.4% oxygen by mass. Its moral mass is 102 g mol- a) calculate the empirical formulae b) calculate the molecular formulae It doesn't make any sense to me cuz when I work it out I get C5H10O4. The mass of this compound is 102 so does that mean that the molecular formulae is the same as the empirical formulae
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