So with basic knowledge of chemistry and the notation used, basic logic can give us the answer. The other one contains Ni, S and O - Ni is going in, but where would the S and O come from? (Technically the O could come from the air I guess, but even allowing for that the S would still be unaccounted for) One of the two possible output solutions contains Ni and Cl - these are going in, so this solution would be possible to produce. Let's look at the options we were given for output: Now, if we can assume that the student in question knows the notations, she can figure out that the elements going in are Ni, H and Cl. two chemicals to be mixed, with their formulas:.two solutions with their names, colors and formulas:. If you add nickel, Ni(s), to hydrochloric acid, HCl(aq), what color solution do you expect? Nickel chloride, NiCl2(aq), is a yellow solution. Nickel sulfate, NiSO4(aq) is a green solution. Let's look at what is given in the Question: The other answers provide valuable insight into what actually happens and are very helpful in understanding the chemistry behind it.īut to correctly answer the question, a much more basic understanding of chemistry (and how tests work) would suffice. You can absolutely contest this, but at least now you understand what the question wanted you to say and how they expected you to arrive at that conclusion. Overthinking it may cause you to arrive at a different answer than was expected, which will lead you to getting the question wrong. The question does not expect you to know, be able to figure out, or go research what color the solution will actually be if you do the reaction in the laboratory. Since the described reaction will yield nickel chloride (not nickel sulfate), the question is expecting you to answer that the solution will be yellow in color. From left to right: $\ce,$ is a yellow solution.Įssentially, you're supposed to decide which of these two salt solutions will be formed by the described reaction. For starters, let’s look at solutions of nickel(II):įigure 1: Nickel(II) solutions. You can do the same thing with frosted glass beads which, when in air, scatter a lot but in water become virtually invisible.The question is really badly worded. If you could add a solvent say dichloromethane which has a high refractive index and will probably not dissolve the ppt then the crystals can be made to almost disappear as scattering is now far less. The amount of reflection at each surface depends on the difference in refractive index between the crystal and air for the wavelength of light used. If the ppt is coloured then absorption of light occurs at some wavelengths as well as scattering at all wavelengths.Īt the surface of a crystal some small fraction of light is reflected, but with millions of randomly oriented crystals numerous reflections occur. If you use red light to illuminate then the 'white colour' will become red. So the 'whiteness' is due to the scattering of light back towards your eyes after the light is repeatedly reflected of the many facets of the many crystals in the ppt. The 'white colour' is due to the fact that the product does not absorb light in the visible part of the spectrum but forms as many fine crystals which in themselves scatter room lights.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |