Solutions to Metric Unit Conversion Problems

Solution to Problem #1: The absolute exponential distance between kilo- (103) and pico- (10¯12) is 1015. This problem can be done two ways.

Method #1: Convert km to pm

40,075.02 km times (1015 pm / 1 km) = 4.007502 x 1019 pm

4.007502 x 1019 pm / (140 pm per atom) = 2.86 x 1017 atoms

Method #2: Convert pm to km

140 pm times (1 km / 1015 pm) = 1.40 x 10¯13 km

40,075.02 km / (1.40 x 10¯13 km/atom) = 2.86 x 1017 atoms

Comment: this amount of Pd is:

2.86 x 1017 / 6.022 x 1023 mol¯1 = 4.75 x 10¯7 mol

and weighs:

4.75 x 10¯7 mol x 106.42 g mol¯1 = 5.06 x 10¯5 g

Solution to Problem #2: When I solved this problem, I did not clear the calculator at any point before rounding off the answer to three significant figures.