The molar enthalpy of formation for H2O(l) is –285.8 kJ·mol–1.  Which expression describes the enthalpy change for the reaction:2H2O(l)2H2(g) + O2(g)                ΔH° = ?  Data sheet and Periodic Table

In a 10.0 L vessel at 100.0 oC, 10.0 grams of an unknown gas exert a pressure of 1.13 atm.   What is the gas? Data sheet and Periodic Table

Which calculation can be used to determine the standard enthalpy of formation of NO(g)?N2(g) + 2O2(g)2NO2(g)              ΔH°1NO(g) + ½O2(g)NO2(g)              ΔH°2   Data sheet and Periodic Table

Which set of quantum numbers is correct and consistent with n = 4?  Data sheet and Periodic Table

What is the mass (in g) of 0.935 mol of acetone, CH3COCH3?  The molar mass of acetone is 58.08 g∙mol–1.   Data sheet and Periodic Table

Strontium (Sr, atomic number 38, average atomic mass = 87.62) naturally exists as 4 stable isotopes with masses of 84, 86, 87, and 88.  Which statement is correct?  Data sheet and Periodic Table

What is the formal charge on nitrogen in the nitrate ion?           Data sheet and Periodic Table

What is the atomic number of an ion with a –2 charge when it has 18 electrons?   Data sheet and Periodic Table

How many valence electrons are in one acetate ion, CH3COO–?  Data sheet and Periodic Table

In the compound (NH4)2S2O3, which element is present in the largest percent by mass?  Data sheet and Periodic Table