17

The question is really badly worded. For starters, let’s look at solutions of nickel(II): Figure 1: Nickel(II) solutions. From left to right: $\ce{[Ni(NH3)6]^2+}$, $\ce{[Ni(en)3]^2+}$, $\ce{[NiCl4]^2-}$, $\ce{[Ni(H2O)6]^2+}$. Image taken from Wikipedia, where a full list of authors is available. You can ignore the left two but the rightmost is a standard ...


8

Jan already gave a great answer explaining the real chemistry behind this, which you and your daughter should absolutely read. This answer also makes the point that the question is poorly worded and could be contested on that basis—that is absolutely true, but unfortunately rather common in high school chemistry courses. In high school chemistry, one ...


7

Anhydrous nickel chloride is yellow. However most simple divalent salts of nickel are green. This should be good enough for high school. The question is poorly worded because it is ambiguous (hopefully the textbook will improve it). If they discuss metal complexes it can be mentioned that $\ce{[Ni(H2O)6]^2+}$ is green in color.


3

Yes, they are related. The first comes directly from the conservation of number of moles of the solute in a dilution, $$n_1 = n_2 $$ Since $n = MV$, $$M_1 V_1 = M_2 V_2$$ The second is related to the conservation of the total number of moles in an isothermal compression or expansion, $$n_1 = n_2$$ Using the ideal gas law $n = pV/RT$, $$\frac{P_1 V_1}{...


3

Most metal nitrates decompose on heating to give metal oxides. Decomposition of silver nitrate is different as it yields elemental silver. $$\ce{2AgNO3 -> 2Ag + O2 + 2NO2}$$ Usually the metals which lie very low in the activity series decompose to give their elemental form. I don't think it's possible to extract metals from just any nitrate by strong ...


2

$\ce{HSO4-}$ is acidic ($\mathrm pK_\mathrm a = 1.99$) yet also reacts as a nucleophile e.g. in the acid-catalysed hydration of olefins, which according to my mechanism lecture procedes via a sulphate diester intermediate. If I thought for long enough, I probably could come up with a basic compound that acts as an electrophile in a given situation. However,...


2

It reacted with the baking soda and is no longer sulfuric acid, but much safer sodium sulfate. If you're unsure, add more baking soda until it no longer fizzes. The remaining white powder is a mix of baking soda or $\ce{NaHCO3}$, and sodium sulfate, $\ce{Na2SO4}$. It safe to wipe up with a damp rag and fairly harmless to touch. Just avoid getting the ...


1

The other answers provide valuable insight into what actually happens and are very helpful in understanding the chemistry behind it. But to correctly answer the question, a much more basic understanding of chemistry (and how tests work) would suffice. Let's look at what is given in the Question: Nickel sulfate, NiSO4(aq) is a green solution. Nickel ...


1

$$\ce{Mn^{2+} + Cr2O7^{2-} -> Mn^{3+} + Cr^{3+}}$$ If you were to balance this reaction, using the appropriate molecules of water and protons, you'd get: $$\ce{ Mn^{2+} + Cr2O7^{2-} + 14H+ + 5e- -> Mn^{3+} + 2Cr^{3+} + 7H2O }$$ The presence of protons the left side of equation suggests that this reaction has a higher rate when the concentration of ...


1

Tetrakis(triphenylphosphano)palladium(0) or $\ce{[Pd(PPh3)4]}$ is a common catalyst in organic chemistry that features a palladium(0) core with four triphenylphosphane ligands. It is a bright yellow, sometimes described as canary yellow. See the image below (taken from Wikipedia, where a full list of authors is available); however, I feel the picture doesn’t ...


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