The name of the sub-atomic particles in the nucleus of atom are protons and neutrons
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Answer:
Noble gases are a unique set of elements in the periodic table because they don't naturally bond with other elements.
Explanation:
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Answer: A. It can identify the elements in the sample.
Explanation: on edge
Answer:
![\% Fe^{+2}=70%](https://tex.z-dn.net/?f=%5C%25%20Fe%5E%7B%2B2%7D%3D70%25)
Explanation:
Hello,
In this case, we could considering this as a redox titration:
![Fe^{+2}+(Cr_2O_7)^{-2}\rightarrow Fe^{+3}+Cr^{+3}](https://tex.z-dn.net/?f=Fe%5E%7B%2B2%7D%2B%28Cr_2O_7%29%5E%7B-2%7D%5Crightarrow%20Fe%5E%7B%2B3%7D%2BCr%5E%7B%2B3%7D)
Thus, the balance turns out (by adding both hydrogen ions and water):
![Fe^{+2}\rightarrow Fe^{+3}+1e^-\\(Cr_2^{+6}O_7)^{-2}+14H^++6e^-\rightarrow 2Cr^{+3}+7H_2O\\\\6Fe^{+2}+(Cr_2^{+6}O_7)^{-2}+14H^++6e^-\rightarrow Cr^{+3}+7H_2O+6Fe^{+3}+6e^-](https://tex.z-dn.net/?f=Fe%5E%7B%2B2%7D%5Crightarrow%20Fe%5E%7B%2B3%7D%2B1e%5E-%5C%5C%28Cr_2%5E%7B%2B6%7DO_7%29%5E%7B-2%7D%2B14H%5E%2B%2B6e%5E-%5Crightarrow%202Cr%5E%7B%2B3%7D%2B7H_2O%5C%5C%5C%5C6Fe%5E%7B%2B2%7D%2B%28Cr_2%5E%7B%2B6%7DO_7%29%5E%7B-2%7D%2B14H%5E%2B%2B6e%5E-%5Crightarrow%20Cr%5E%7B%2B3%7D%2B7H_2O%2B6Fe%5E%7B%2B3%7D%2B6e%5E-)
Thus, by stoichiometry, the grams of Fe+2 ions result:
![m_{Fe^{+2}}=0.04021\frac{molK_2Cr_2O_7}{L}*0.02872L*\frac{6molFe^{+2}}{1molK_2Cr_2O_7}*\frac{56gFe^{+2}}{1molFe^{+2}}=0.388gFe^{+2}](https://tex.z-dn.net/?f=m_%7BFe%5E%7B%2B2%7D%7D%3D0.04021%5Cfrac%7BmolK_2Cr_2O_7%7D%7BL%7D%2A0.02872L%2A%5Cfrac%7B6molFe%5E%7B%2B2%7D%7D%7B1molK_2Cr_2O_7%7D%2A%5Cfrac%7B56gFe%5E%7B%2B2%7D%7D%7B1molFe%5E%7B%2B2%7D%7D%3D0.388gFe%5E%7B%2B2%7D)
Finally, the mass percent is:
![\% Fe^{+2}=\frac{0.388g}{0.5562g}*100\%\\ \% Fe^{+2}=70%](https://tex.z-dn.net/?f=%5C%25%20Fe%5E%7B%2B2%7D%3D%5Cfrac%7B0.388g%7D%7B0.5562g%7D%2A100%5C%25%5C%5C%20%20%5C%25%20Fe%5E%7B%2B2%7D%3D70%25)
Best regards.