Manganese dioxide (MnO2(s), Delta. Hf = –520.0 kJ) reacts with aluminum to form aluminum oxide (AI2O3(s), Delta. Hf = –1699.8 kJ/mol) and manganese according to the equation below. 3 upper M n upper O subscript 2 (s) plus 4 upper A l (s) right arrow 2 upper A l subscript 2 upper O subscript 3 (g) plus 3 upper M n (s). What is the enthalpy of the reaction? Use Delta H r x n equals the sum of delta H f of all the products minus the sum of delta H f of all the reactants.. –1,839.6 kJ –1,179.8 kJ 1,179.8 kJ 1,839.6 kJ

Ageochemist examines a piece of metal that he found in the soil. he performs tests to identify the metal from its density, electrical conductivity, and melting point. which statement best describes his investigation? a. he is determining physical properties that are sufficient to identify the metal. b. he is determining chemical properties that are sufficient to identify the metal. c. he is determining physical properties that are insufficient to identify the metal. d. he is determining chemical properties that are insufficient to identify the metal.

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.

Why is retrograde motion an apparent motion