CHEMISTRY 1112

Review Quiz 4

Summer Session II

 

  1. The solubility of borax at room temperature is about 6.3 g/100mL.  Assuming the formula of borax to be Na2B4 O5(OH)4 8H2O (molar mass = 313.34 g/mol), what is the molar solubility of borax and what is the Ksp of borax at room temperature? [Answer: molar solubility = 0.20 mol/L, Ksp = 3.3 x 10-2]

 

 

 

 

 

  1. The dissolution of most salts is an endothermic process, a process that absorbs energy from the surroundings.  Explain why/how and endothermic process can be spontaneous.

 

 

 

 

  1. A .406g sample of anhydrous sodium carbonate (molar mass = 106 g/mol) is used as a primary standard to standardize a hydrochloric acid solution. If 19.6 mL of the HCl solution is required to reach the stoichiometric point in the titration, what is the molar concentration of the HCl solution? [Answer: 0.391 M HCl]

 

 

 

 

 

 

 

  1. Oxidation occurs at the (anode, cathode) and is connected to the (positive, negative) terminal of the voltmeter in a galvanic cell.

 

 

 

 

  1. Why is it not possible to use a nonmetal as an electrode in a nonmetal-nonmetal ion redox couple, such as the Cl2/Cl-redox couple?