Answer:
the entropy change for the surroundings when 1.68 moles of Fe2O3(s) react at standard conditions = 49.73 J/K.
Explanation:
3Fe2O3(s) + H2(g)-----------2Fe3O4(s) + H2O(g)
∆S°rxn = n x sum of ∆S° products - n x sum of ∆S° reactants
∆S°rxn = [2x∆S°Fe3O4(s) + ∆S°H2O(g)] - [3x∆S°Fe2O3(s) + ∆S°H2(g)]
∆S°rxn = [(2x146.44)+(188.72)] - [(3x87.40)+(130.59)] J/K
∆S°rxn = (481.6 - 392.79) J/K =88.81J/K.
For 3 moles of Fe2O3 react, ∆S° =88.81 J/K,
then for 1.68 moles Fe2O3 react, ∆S° = (1.68 mol x 88.81 J/K)/(3 mol) = 49.73 J/K the entropy change for the surroundings when 1.68 moles of Fe2O3(s) react at standard conditions.
The Bohr Model, which was proposed by Niels Bohr in 1913
Strong acids can dissolve the salts of weak acid. When we consider the different salts of silver:
Salts of silver with the conjugate bases of a weak acid are soluble in strong acidic solutions. Some of these salts are:
![2Ag^{+}(aq)+CO_{3}^{2-}(aq) --->Ag_{2}CO_{3}(s)](https://tex.z-dn.net/?f=2Ag%5E%7B%2B%7D%28aq%29%2BCO_%7B3%7D%5E%7B2-%7D%28aq%29%20---%3EAg_%7B2%7DCO_%7B3%7D%28s%29)
![Ag^{+}(aq)+C_{2}H_{3}O_{2}^{-}(aq)-->AgC_{2}H_{3}O_{2}(aq)](https://tex.z-dn.net/?f=Ag%5E%7B%2B%7D%28aq%29%2BC_%7B2%7DH_%7B3%7DO_%7B2%7D%5E%7B-%7D%28aq%29--%3EAgC_%7B2%7DH_%7B3%7DO_%7B2%7D%28aq%29)
![2Ag^{+}(aq)+SO_{3}^{2-}(aq) --->Ag_{2}SO_{3}(s)](https://tex.z-dn.net/?f=2Ag%5E%7B%2B%7D%28aq%29%2BSO_%7B3%7D%5E%7B2-%7D%28aq%29%20---%3EAg_%7B2%7DSO_%7B3%7D%28s%29)
Salts of silver with the conjugate bases of a strong acid are not affected by change in pH:
![Ag^{+}(aq)+Cl^{-}(aq) --->AgCl(s)](https://tex.z-dn.net/?f=Ag%5E%7B%2B%7D%28aq%29%2BCl%5E%7B-%7D%28aq%29%20---%3EAgCl%28s%29)
![2Ag^{+}(aq)+SO_{4}^{2-}(aq) --->Ag_{2}SO_{4}(s)](https://tex.z-dn.net/?f=2Ag%5E%7B%2B%7D%28aq%29%2BSO_%7B4%7D%5E%7B2-%7D%28aq%29%20---%3EAg_%7B2%7DSO_%7B4%7D%28s%29)
These two salts with Chloride and sulfate ions are not soluble in acidic solutions as the salts of silver with the conjugate bases of a strong acid are not soluble in acidic solutions, they remain unaffected by any change in pH.
So for salts of Ag and Ba with the conjugate bases of a weak acid, solubility is increased upon the addition of an acid. So, the interference from the ions of weak acids can be removed by decreasing the pH.
Answer:
D) sodium t-butoxide + bromomethane
Explanation:
The alkoxide ion is a strong nucleophile, that unlike alcohols, will react with primary alkyl halides to form ether. This general reaction is known as <em>the Williamson synthesis</em>, and is a SN₂ displacement. The alkyl halide must be primary so the back side attack is not hindered, and the alkoxide ion must be formed with the most hindered group.
The mechanism can be seen in the attachment.