Flashback Problems


6.     How much energy in kJ does a 120 V appliance drawing 2.5 A current use in 6 hours?



This question is out of place. We will cover it in the next section.



7.     If eight 10 W resistors are connected in parallel to a 120 V source, how much current will be drawn by each resistor? Draw out this situation before you tackle the problem.


I=V/R = 120 V /10 W = 12 A. Recall that voltage is constant in parallel.


8.     What two families of the periodic table form compounds involving the +1 and +2 ions, respectively?


Alkali metals (first column)  form +1 ions

Alkaline earth metals (2nd column)  form +2 ions



9.     Specific heat is a characteristic physical property.


          a.       Give another physical characteristic property for water.


          Density, or boiling point or melting point


b.       Give a characteristic chemical property of water.   


          2 moles of water can react to produce hydrogen and oxygen in a 2:1 ratio.