Malinn

I have been given a graph to sketch. The original graph was: T= 20-4cos(pi(x-1)/12) I think I understand how to graph this , but later on they change it to this: T= 20-loge(x) 4cos(pi(x-1)/12) What type of graph is that? I don't even know if it exists, as I can't find anything in the textbook. I know it must follow the same shape as a log graph would because it asks you to do this after sketching the second graph: If the cycle starts at midnight Sunday, what day(s) will the temperature of the pool be more than 24.5 degrees celcius? (Just days not times) So could someone please tell me how to graph it? I have a "Texas Instruments Ti-nspire CAS" if that helps Thanks alot.

I undertook a practical experiment where a back titration was used to determine the amount of nitrogen in fertiliser.My titres are 3.9, 3.7 and 4.2 So I know this reaction occurred: NH4+ + OH- ---> NH3 +H2O I then boiled the solution to expel the Ammonia which means the excess OH- ions were titrated against 0.1 M HCl. I think? NaOH- +HCl ---> NaCl +H2O Is this equation correct? If so are the following calculations correct too? n (HCl)= 0.1 x 0.0039 n(HCl)=0.0039 If this calculation is correct, what do I have to do next?

We did an experiment to find out how much sulphate was in a sample of homemade fertiliser. This is the method: Å Finely grind a small quantity of fertiliser using a mortar and pestle. Weigh out accurately about 1.0 g of fertiliser into a 100 mL beaker. Record the mass of fertiliser to three decimal places. Ç Add about 50 mL of deionised water and stir to dissolve as much of the fertiliser as possible. Filter the mixture into an approx. 500 mL beaker, washing the residue (the solid trapped in the filter paper) several times with a small amount of deionised water. É Add about 3 mL of 2 M hydrochloric acid to the filtrate (the solution passes through the filter paper) and then add more deionised water so that the total volume of solution is now about 200 mL [Don't have the total volume of solution larger than about 200 mL as both boiling and filtering will take too long.] Ñ Boil the solution for 3 minutes. Ö Slowly add 15 mL of 0.5 M barium chloride solution to the hot solution, stirring all the time. Record your observations. Ü Boil for another minute, then remove the beaker from the heat and allow the beaker and contents to cool. á This step is only feasible if your barium sulfate clumps sufficiently for it to settle. Ensure that no more sulfate ions remain in solution by adding a couple of drops of barium chloride solution to the supernatant solution. (If more BaSO4 forms, add 3 mL more barium chloride solution to precipitate the remaining sulfate ions.) à Name a filter paper around the edge using a pencil or insoluble ink and weigh the named filter paper. Once again, record its mass to three decimal places. â Filter the barium sulfate using a buchner funnel and vacuum filtration - filtration is more rapid if most of the solution is filtered before the bulk of the solid is poured on to the filter paper. Ensure that the solid remains on the paper. ä Carefully remove the damp filter paper and residue from the Buckner funnel, put it where directed and allow the filter paper and barium sulfate to dry overnight. Then, reweigh the filter paper and barium sulfate. The weight of my precipitate was 1.5575g I understand that we are fidning the concentration of sulphate in the feriliser, I just don't understand what the precipitate consists of. Is it pure sulphate (because you use BaCl2 to neutralise the BaSO4) or is it actually BaSO4 and I am required to calculate the amount of sulphate? And also, what do I write in my results analysis section? I thought we would be told what the correct measurement was so we could compare and contrast, but we haven't so now I'm confused about how I analyse my results.