Chapter 2 Homework – 30 points total (front and back pages)

Unit Conversions/Significant digits/Scientific Notation Homework

Convert the following:  (Answers are in ()’s and are for the exponent of the answer ONLY.                                

1.  3.45 Km to m    (3)                                                    10.  3.45 x 105 mm to cm (4)

2.  4.87 m to Km    (-3)                                                   11.  5.78 x 108 cm to Km (3)

3.  1.87 m2 to Km2 (-6)                                                 12.  6.87 x 10-2 cm to mm (-1)             

4.  4.79 Km2 to m2 (6)                                                  13.  8.90 x 10-5 mm to Km (-11)

5.  8.97 mm to cm (-1)                                                 14.  9.00 x 10-12 mm2 to Km2 (-24)

6.  9.08 mm to dm (-2)                                                 15.  4.56 x 10-15 cm2 to m2 (-19)

7.  8.67 cm2 to Km2 (-10)                                                      

8.  7.54 Km3 to pm3 (45)                                                        See p. 40-42 of your textbook for extra help

9.  5.90 mm to Km (-6)

Significant Digits:  (Sometimes these are called “sig figs” for short)
How many significant digits are in the following numbers?  Make sure you know all of the rules for significant digits before any test or quiz.

16.  100                                                                          24.  765.0

17.  1000                                                                        25.  0.765

18.  1000.0                                                                     26.  0.0000203

19.  101                                                                          27.  0.002000

20.  100.                                                                         28.  0.100020

21.  0.00001                                                                   29.  200 x 10-3

22.  0.001                                                                       30.  450 x 10-5

23.  100.00001                                                                        See p. 47-48 of textbook for sig fig rules and for

                                                                                                rules on rounding numbers.

Scientific Notation:

If a number is written in scientific notation, change it into a decimal number.  If a number is written as a decimal number, change it into scientific notation in standard form (eg.  1.23 x 103).  Round any decimal numbers to the correct number of significant digits when you put it in scientific notation. (Answers in ()’s)

31. 4.56 x 105                (456000)                                                40.  6780000          (6.78x106)

32. 3.45x 10-5                 (0.0000345)                                           41.  598201            (5.98201x105)

33. 44.6 x 105                 (4460000)                                              42.  0.0000236       (2.36x10-5)

34. 12.3x 10-5                 (0.000123)                                             43.  0.0980             (9.80x10-2)

35. 136 x 103                  (136000)                                                44.  9.76                 (9.76x100)

36. 187 x 10-3                 (0.187)                                                   45.  0.00000000000003769  (3.769x10-14)

37. 154323 x 10-2       (1543.23)                                               DON’T JUST DO THESE IN YOUR HEAD!

38. 25433 x 10-2       (254.33)                                                 PUT PENCIL TO PAPER!                               

39. 4.56 x 100           (4.56)                                                               See p. 50-52 of textbook for help.

 

Scientific notation with division and multiplication:

     Multiply or divide the following problems dealing with scientific notation.  All answers are to be in scientific notation with only one significant digit.  Notice that all of these must have only one sig fig in their answer because that is the least in all of the problems!  (See p. 51-52 of your textbook for help)

 

46. 10 x 1015/5.00 x 105          (2x1010)                                         51. (5 x 105)  (2 x 105)        (1x1011)

47. 10 x 10-15/5.00 x 105        (2x10-20)                                        52. (5 x 10-5)  (2 x 10-5)       (1x10-9)

48. 10 x 10-15/5.00 x 10-5      (2x10-10)                                        53. (8 x 10-5)  (10 x 105)      (8x101)

49. 40 x 10-5/20 x 1010            (2x10-15)                                        54. (2 x 1015)  (10 x 10-20)    (2x10-4)

50. 40 x 10-5/4.56 x 10-10       (9x105)                                         55. (9 x 10-8)  (10 x 10-10)    (9x10-17)

 

What’s going to be on the quiz:

1.  Conversion questions (Remember how to do it if something is squared or cubed?)

2.  Significant digits (you’ll get a number and be asked how many sig figs are in it)

3.  Converting scientific notation to decimal form and back again.

4.  Density problems like those found on the other side of this paper (word problems like those)

5.  Problems like the conclusion questions #1-8 on Bubble Lab.  You’ll be given some data and need to create a graph and a conversion factor. 

 

Density Homework

 

 

All answers are to be in decimal form (not scientific notation).  All answers need to be rounded to the correct number of significant digits.

 

1.  A rock with a density of 4.56 g/mL and a mass of 3.45 g has what volume? (0.757 mL)

 

 

 

2.  A rock with a mass of 4.59 g and a volume of 5.78mL has what density? (0.794 g/mL)

 

 

 

3.  A rock with a volume of 10.0 mL and a density of 3.87 g/mL has what mass? (38.7 g)

 

 

 

4.  A marble with a density of 8.93 g/mL and a mass of 9.00 g has what volume? (1.01 mL)

 

 

 

5.  A marble with a volume of 80.9 mL and a density of 1.90 g/mL has what mass? (154 g)

 

 

 

6.  A boat with a mass of 9.04 x 105 Kg and a volume of 8.90 x 107 mL has what density (notice that you will have to convert Kg into grams before beginning this problem).  (10.2 g/mL)

 

 

 

7.  A styrofoam ball with a density of 1.05 g/L and a volume of 5.90 mL will have what mass?  (notice that you will have to convert g/L into g/mL before beginning this problem). (0.00620 g – that’s 3 sig figs)

 

 

 

8.  A computer monitor with a density of 89.0 Kg/mL and a volume of 5.00 L will have what mass?  (notice that Kg/mL will have to be converted to g/mL and volume will need to be converted to mL before beginning this problem.)  (445,000,000 g or 4.45 x 108g)

 

 

 

9.  A stapler with a mass of 3.48 Kg and a density of 9.00 g/L will have what volume?

(387,000 mL or 3.87 x 105mL)

 

 

 

10.  A watch with a mass of 0.09 Kg and a volume of 18.0 mL will have what Density? (5 g/mL)

 

 

 

REMEMBER:

1 L = 1 dm3

1 L = 1000 mL

1mL = 1 cm3