2021年AP化学简答题真题+答案+PDF下载
1. Methanoic acid, HCOOH, ionizes according to the equation above.
(a) Write the expression for the equilibrium constant, Ka, for the reaction.
(b) Calculate the pH of a 0.25 M solution of HCOOH.
(c) In the box below, complete the Lewis electron-dot diagram for HCOOH. Show all bonding and nonbonding valence electrons.
(d) In aqueous solution, the compound H2NNH2 reacts according to the equation above. A 50.0 mL sample of 0.25M H2NNH2（aq)is combined with a 50.0 mL sample of 0.25 M HCOOH(aq) .
(i) Write the balanced net ionic equation for the reaction that occurs when H2NNH2 is combined with HCOOH.
(ii) Is the resulting solution acidic, basic, or neutral? Justify your answer.
When a catalyst is added to a solution of HCOOH(aq), the reaction represented by the following equation occurs.
HCOOH(aq) → H2(g)+CO2(g)
(e) Is the reaction a redox reaction? Justify your answer
(f) The reaction occurs inarigid 4.3 L vessel at 25°C, and the total pressure is monitored, as shown in the graph above. The vessel originally did not contain any gas. Calculate the number of moles of CO2(g) produced in the reaction. (Assume that the amount of CO2(g) dissolved in the solution is negligible.)
(g) After the reaction has proceeded for several minutes, does the amount of catalyst increase, decrease, or remain the same? Justify your answer.
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