Topic content:
A chemical reaction takes place in the container, during which there are six substances: H2O, H2S, S, NH4+, H+, NO3. The curve of the amount of NO3 - and S measured in the reaction process versus time is shown in the figure. The following judgments are correct
A. The stoichiometric ratio of oxidant and reducing agent after balancing is 1:4
B. Sulfur is reduced in the reaction
C. The reducing agent is a substance containing NH4+
D. If 1mol NH4+is generated, 2mol electrons are transferred.
Best answer:
A
Answer analysis:
It can be seen from the image that with the reaction going on, the amount of substance S increases, which should be the product, then H2S is the reactant, while the amount of substance NO3 - decreases, which should be the reactant, then NH4+is the product. Then according to the principle of redox reaction, the ionic equation of the reaction can be written as: 2H ++ NO3 - + 4H2S=NH4 ++ 4S + 3H2O, the chemical equation is: 2HNO3 + 4H2S=NH4NO3 + 4S + 3H2O, the oxidant is HNO3, and the reducing agent is H2S. Since only 1mol HNO3 in 2mol HNO3 undergoes redox reaction, the ratio of oxidant to reducing agent is 1:4, and item A is correct; S is oxidation product, item B is wrong; The substance containing NH4+is a reduction product, item C is wrong; If 1molNH4+is generated, 8mol of electrons will be transferred, and item D is wrong.
Test core:
Introduction to balancing: The chemical reaction equation strictly abides by the law of conservation of mass. After writing the chemical reaction equation and writing the reactants and products, the number of atoms on the left and right sides is often not equal, which does not meet the law of conservation of mass, which needs to be solved by balancing.