Problem Set 1.9:       Unit 1 Review

 

Note: Show all work and correct units throughout each calculation. Use correct sig. figs when doing calculations

1.   Define

         a) element a pure substance made up of only one kind of atom

         b) matter anything that has mass and occupies space

         c) compound a pure substance made up of two or more kinds of atoms

         d) mixture two or more pure substances placed together/mixed

         e) inference a conclusion drawn from observed information

         f) observation gathering information using the five senses

         g) hypothesis an educated guess/temporary explanation

         h) kinetic energy energy of movement

         g) classification organizing items into groups based upon similarities

         h) interpretation any knowledge obtained indirectly to describe or explain a substance or process

         i) accuracy how close one comes to an accepted value

         j) uncertaintythe amount of imprecision in a measurement

         k) precision number of decimal places in a measurement

 

2.     Describe the difference between chemical and physical change in terms of what occurs with the atoms involved. Chemical – atoms are rearranged to form new chemicals; Physical – atoms speed up or slow down (NO NEW CHEMICALS ARE MADE)

 

3.     A sample of an element has a mass of 146.28 g and will displace 27.50 mL of water. What is the density and identity of the element?             5.319 g/mL  germanium

 

4.   Draw the heating curve for zinc, as it is heated from a solid to a gas. Indicate its m.p. and  b.p. and use correctly labeled axes.

 

5.   State the element that has a:

            a) m.p. of 1064 °C                                                                  gold Au

            b) b.p. of 2831°C                                                                    scandium Sc

            c) density of 6.15 g/cm3                                                            lanthanum La

               d) a freezing point of 631°C                                                   antimony Sb

 

6. Describe each of the following as a physical or chemical change.

        a) snow changes to water on a hot day                                                     physical

        b) an egg is fried on a frying pan                                                               chemical

        c) wood is burned in a fire place                                                               chemical

        d) ice cubes shrink in a freezer                                                                  physical

        e) irons rusts (Fe + O2        Fe2O3)                                                          chemical

 

7.   What volume does 852.6 g of lead take up?         74.8 mL

 

8.   What mass does 17.358 mL of mercury have?     236 g

 

9.   Draw the cooling curve for iodine. Indicate the mp, bp and label each axis.

 

10. State what WHMIS and MSDS stand for? (make sure you study the safety section of your Study Guide!) WHMIS – workplace hazardous materials information system ; MSDS material safety data sheet

 

11. What word describes the change from a

        a) solid to a gas                                                   sublimation

        b) gas to a liquid                                                  condensation

        c) liquid to solid                                                  freezing /solidification

        d) liquid to gas                                                    vaporization

 

12. State the number of significant digits for each number:

      a)  25.0 g   3          b)       1000 g  infinite           c)  25.036 A    5          d)  5.214  x  10-62  mL   4

                                                1 kg

e) 0.0000005 L      1                      f) 8.2000 m 5

13. Determine the average and uncertainty given the following measurements from a

a) centigram balance (in g): 82.62 g  82.54 g  82.48 g  82.72 g  82.65 g                             82.6 ± 0.1 g

b) decigram balance (in g):    236.74, 236.65, 236.68, 236.78, 236.75, 236.79, 236.73      236.73 ± 0.08 g

c) voltmeters (in mV):    5.812, 5.810, 5.826, 5.815, 5.823, 5.807                              5.82 ± 0.01 mV

14. Perform the following calculations quoting answers to the appropriate number of significant figures.

(Assume that all numbers come from measurements!)

a)  18 - 0.21                                   18                    b)   620.1  x  30451.56   1.888 x 107

c)  2.1262 L + 253 mL + 6.0 cL    2.44 L              d)   (9.4  x  10-3)(3.21  x  106)   3.0 x 104

e)  276.4  +  7.2295                       283.6               f)   (10)(25)   3 x 102

g)  60.55 - 0.2  =                           60.4                 h)   41.7  x  702.15 =   2.93 x 104

i)   34.912 + 1.5 + 253.48 =          289.9               j)    (4.418  x  10-15)(6.02  x  1023)  =    2.66 x 109

k) (9.054  x  10-6) + (3.5  x  10-7)  9.40 x 10-6       l)    (4.321  x  10-8)(2.54  x  1045)    =    2.31 x 1013

                                                                                 (9.2465  x  109)(5.14233  x  1014)

15. Complete the relationships.

a)                          1 Mg  =                       1 000 000 g                    c)                      100 m  =                       1 hm

b)                         100 cL            =                       1 L                  d)                      1000000µL          =                       1 L

 

16. Use unit analysis to perform the following conversions:

a) 6.372 hL to mL            6.372 x 105 mL

b) 4.9 x 1015 µg to Mg     4.9 x 103 Mg

c) 8.774 x 103 cm3 to m3  0.008774 m3

 

17. Given the following relationships, determine how many zings can be obtained when you trade 20.6 balls.

            4 clangs  = 3 dangs    7 dangs  = 3 jars        2 balls  = 5 clangs      6 jars  = 1 zing  2.76 zings