Ch. 5 measurement & calculations                              30 points                                   chemistry

In problems involving any calculation, show your work in an organized manner, include (i) any relevant equation (or formula), (ii) conversion factor(s), (iii) put the proper units in your calculations and answer, and (iv) have the proper number of significant figures in your answer.

If you use Mathematica, state that you used it, write the command, and answer.  Scoring will tend to be “all or none” with minimal / no points for any error in your code.

1. Fill-in the blank.  [10 points]

a.  Express the number, 0.0000203 using scientific notation:  ___________________________

b.  123.456  +  34.57  =  ________________

c.  5789 ÷  25  =  _____________________ (it’s a division problem)

d. The number of significant figures in  0.0000203 is  _________

e. 5789 *  25  =  _____________________

2.  Solve.  [10 points]

a.  7.25 * 105 cm =  __ km

b. a student ran 5.0 km in 19.0 minutes; what is the student’s pace in minutes per mile ?  hint: 1.0 mile = 1760 yards exactly and 1.0 inch = 2.54 cm, exactly.

3. In a lab activity, when a 125.0 g cylinder is put into a graduated cylinder with 35 mL of water, the volume of water rises to 42 mL.  What is the density of the cylinder ?  [10 points]