Blog

What is the percent by mass of oxygen in (NH4)2SO3?

How many protons, electrons, and neutrons (respectively) are in an atom of iodine-131?     

Use the Lewis dot structure (make sure you show all electron pairs) and VSEPR theory to predict which of the following molecules is polar  

Considering the limiting reactant problem, calculate the number of moles of N2 produced from 2.50 moles of O2 and 4.5 moles of NH3 by the following reaction. 4NH3(g) + 3 O2(g)   →   2N2(g)  + 6H2O(g)

Which of the following pure substances has the lowest vapor pressure?

The following phase change is endothermic:

Answer the following question. Show the answer on the screen provided. After uploading your exam, take the picture of your work and upload it to Exam 4 Solutions, Extra Credit, and Partial Credit assignment. Your work must reflect the answer provided here. NO CREDIT will be awarded for the answer without work shown. Standard Enthalpies of Formation, in kJ/mol ΔHof     ΔHof NO(g)       +90.25           NO2(g)      +33.2        NH3(g)     -45.9          N2O(g)        81.6   H2O(l)        -285.8         H2O(g)         -241.8 Use the properties of enthalpy as a state function (version of Hess’s law) and  data above to calculate the enthalpy change for the reaction (Hint: Do not forget about the coefficients):                                         8 NO2(g)  + 6 NH3(g)  =>  7 N2O(g)  +  9 H2O(g)                      ΔH = ?  

If the heat produced by the reaction of combustion of 1 mole of ethanol is 8 kJ/mol, (see the thermochemical equation below), how much heat in kJ is produced by the combustion of 155 g of ethanol at the same conditions (MMethanol= 46.07 g/mol)? C2H6O(g) + 3O2(g)  → 2CO2(g) + 3H2O(g);       ∆H°rxn=−1366.8 kJ/mol  

Use the appropriate gas law and units to calculate the pressure exerted on a 10.0L container with only 5.0 g of CO2(g) at a temperature of 25 oC

Explain traditional chronology used in history and art history, define terms “b.c.”, “a.d.”, “c”, and no letters accompanying date; describe also religiously neutral chronology – “b.c.e.” and “c.e.”: