Category: Uncategorized

Which balanced thermochemical equation corresponds to the enthalpy of formation (ΔHfo) of carbon monoxide, CO(g)? The enthalpy of formation (ΔHfo) of CO(g) is –110.53 kJ/mol 

What mass of sodium hydroxide (NaOH, molar mass = 40.0 g/mol) is needed to make 100.0 mL of a 0.125 M NaOH solution?

A 1.0 L flask is filled with NO and O2 initially, and after the reaction establishes equilibrium, the flask is found to contain 0.0018 mol NO, 0.0012 mol O2 and 0.78 mol NO2. What is the value of the equilibrium constant, Kc, at this temperature? 2NO(g) + O2(g) ⇌ 2NO2(g)

The density of a 3.539 M HNO3 aqueous solution is 1.150 g/mL at 20 oC. What is the molal concentration? The molar mass of HNO3 is 63.02 g/mol.

What is the molecular geometry around the indicated O atom in the molecule depicted?   

For the process: O2(g) → 2O(g)   ΔH° = 498 kJ/mol What would be the predicted sign of ΔS°rxn and the conditions under which this reaction would be spontaneous?

Which gas, helium or argon, effuses faster under the same conditions and by how much?          

A 1.0 g sample of zinc sulfide, ZnS, is mixed with 100.0 mL of pure water and 100.0 mL of a 0.100 M sodium sulfide, Na2S, solution. Which set of diagrams best represents the two solutions? The Ksp of ZnS is 3.0×10–23, and both solutions are saturated. Water molecules and sodium ions are omitted for clarity.

How many hydrogen atoms are in a 1.0 g sample of acetic acid, CH3COOH? The molar mass of acetic acid is 60.06 g/mol. NA = 6.022 x 1023 mol-1

Which figure best represents what will happen when Pb(NO3)2(aq) is treated with an excess of NaCl(aq)? Water molecules are omitted for clarity.