Without referring to tables, predict which of the following has the higher enthalpy in each case.

(a) 1 mol CO2(s) or 1 mol CO2(g) at the same temperature.
(b) 2 mol of hydrogen atoms or 1 mol of H2.
(c) 1 mol H2(g) and 0.5 mol O2(g) at 25 °C or 1 mol H2O(g) at 25 °C.
(d) 1 mol N2(g) at 100 °C or 1 mol N2(g) at 300 °C.

How does a catalyst increase the speed of a reaction? a. the catalyst eliminates the activated complex stage, allowing products to form immediately. b. the catalyst lowers the energy level of the reactants, making it easier for them to react. c. the catalyst makes it easier for the activated complex to form, lowering the activation energy. d. the catalyst raises the energy level of the products, making the reaction finish sooner. reset next