Chemistry Conversions

Question

A) Convert grams to pounds by converting grams to kilograms and then kilograms to pounds. Then solve:

 

35.4 g/1 X 1 kg/1000 g X 2.2 lb/1 kg

 

 

Solve:

 

B)1,324,000 ug/1 X 1 kg/10^6 ug

Answer 1

The point of this problem is to be able to convert units.  That is called Dimensional Analysis and it uses the Multiplicative Identity (that is, 1).  Any value multiplied by 1 remains the same, but the units might change.  For example:

      1 dollar

      (1 dollar)*1

      (1 dollar)*(100 cents per dollar)

      (1 dollar)*((100 cents) / (1 dollar))

      (1*100)/(1) cents    [dollars cancel, leaving only cents]

      100 cents

 

The identity is:

    1 = ( (100 cents) / (1 dollar) )  =  ( (1 dollar) / (100 cents) ) 

         [select the one so that units will cancel]

 

O.K.,

   35.4 g         [grams]

   (35.4 g) * 1         [identity]

   (35.4 g) * ( (1 kg) / (1000 g) )        [unit conversion; now, cancel units]

    0.00354 kg        [to kg]

    (0.00354 kg)*1

    (0.00354 kg)*( (2.2 lbs) / (1 kg) )             [why?]

    0.007788 lbs     [note: this is far too many digits to be correct; round it!]

 

 

B)1,324,000 ug/1 X 1 kg/10^6 ug

    1324000 μg

    (1324000 μg)*1

    (1324000 μg)*( (1 kg)/(1000000 μg)     [the problem statement]

    0.001324 kg         [note: again, too many digits]