Answer:A(n) molecule that is made up of atoms that are chemically bonded is the smallest recognizable unit of a compound.
Explanation:
The answer is "A. a pure substance can be separated by chemical means, while a mixture can be separated by physical means". A pure substance only has one type of substance, whereas a mixture has more than one. A pure substance therefore, can only be separated chemically, because it is not two things mixed together, whereas a mixture can be separated physically because there are multiple substances.
The Answer is D. a polymer is a substance that has a molecular structure consisting of a large number of similar units bonded together
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.
