Using the following thermochemical data, calculate ∆Hf° of Tm2O3(s). 2TmCl3(s) + 3H2O(l) –> Tm2O3(s) + 6HCl(g) ∆H° = 388.1 kJ/mol 2Tm(s) + 3Cl2(g) –> 2TmCl3(s) ∆H° = –1973.2 kJ/mol 4HCl(g) + O2(g) –> 2Cl2(g) + 2H2O(l) ∆H° = –202.4 kJ/mol

Fe has __________ that is (are) unpaired in its d orbitals.

Nitric acid, HNO3, was first prepared 1200 years ago by heating naturally occurring sodium nitrate (called saltpeter) with sulfuric acid to produce sodium bisulfate and collecting the vapors of HNO3 produced.  Calculate DH°rxn for this reaction.  ∆H°f[NaNO3(s)] = -467.8 kJ/mol; ∆H°f[NaHSO4(s)] = -1125.5 kJ/mol; ∆H°f[H2SO4(l)] = -814.0 kJ/mol; ∆H°f[HNO3(g)] = -135.1 kJ/mol.NaNO3(s)  +  H2SO4(l)  =>   NaHSO4(s) + HNO3(g)

What is the enthalpy change when 49.4 mL of 0.430 M sulfuric acid reacts with 23.3 mL of 0.309 M potassium hydroxide? H2SO4(aq) + 2KOH(aq) –> K2SO4(aq) + 2H2O(l) ∆H° = –111.6 kJ/mol

Of the following elements, which has the lowest first ionization energy?

When 0.236 mol of a weak base (A–) is reacted with excess HCl, 6.91 kJ of energy is released as heat. What is ∆H for this reaction per mole of A– consumed?

What is the energy of a photon of blue light that has a wavelength of 453 nm?

In an investigation of the electronic absorption spectrum of a particular element, it is found that a photon having l = 500 nm provides just enough energy to promote an electron from the second quantum level to the third. From this information, we can deduce

The heat combustion of acetylene, C2H2(g), at 25°C is –1299 kJ/mol. At this temperature, ∆Hf° values for CO2(g) and H2O(l) are –393 and –286 kJ/mol, respectively. Calculate ∆Hf° for acetylene.

Consider the following orderings. I. Na+ < Mg2+ < Al3+ < Si4+ II. Be < Mg < Ca < Sr III. I < Br < Cl < F IV. Al < Si < P < Cl Which of these give(s) a correct trend in ionization energy?