CHEMISTRY WKST
SIGNIFICANT DIGITS / METRIC SYSTEM REVIEW
NAME: __________JMS_________________________
1) Tell how many significant digits are in each of the following quantities.
a) 3200 g
2
f)
b) 106 mL
3
c) 12.006 g
5
4
k) 3.240 g
g) 0.450 ns
3
l)
h) 0.0610 L
3
m) 312.000 s
6
d) 10.204 mL 5
i)
0.00308 g
3
n) 0.1006 cm
4
e) 47000 m
j)
70000 km
1
o) 5.0040 mL
5
2
227.0 g
2.00 x 108 m
4
3
2) The following data readings were taken from a balance reading in hundredths of a gram, a meter stick reading in
thousandths of a meter and a graduated cylinder in tenths of a milliliter. However, some of the readings are wrong in
the way they were recorded. It is your task to look at each reading and decide what the reading should have been
and correct it and then tell how many significant digits are in the new reading. If the reading is correct, write “OK” in
the first blank, but still tell how many significant digits are in the measurement.
a) 12.6731 g
12.67 g
4
e) 0.0741 m
0.074 m
2
i) 50 mL
50.0 mL
3
b) 42.006 m
OK
5
f) 3.399 mL
3.4 mL
2
j) 18.00 g
OK
4
c) 7.423 mL
7.4 mL
2
g) 0.00274 g
0.00 g
1
k) 78421.0062 g 78421.01 g
7
d) 127 mL
127.0 mL
4
h) 200 m
200.000 m
6
l) 0.22 mL
1
0.2 mL
3) In chemistry, rounding numbers correctly is a must. If the digit to the right of the one to be rounded is higher than 5,
round up. If it is less than 5, round down. If it is 5 and there are numbers after it, round up. If it is exactly 5 with no
numbers after it, round to the nearest even number—if this is not done, then when taking large numbers of readings
that are always rounded up, the mean (average) data is higher than is accurate.
Round the following numbers to 3 significant digits.
a) 5.344 x 107
5.34 x 107
d) 7.278278
7.28
g) 5,555,555
5,560,000
b) 6.6888 x 10−4 6.69 x 10−4
e) 4.997997
5.00
h) 6.9851
6.99
c) 6.675
f)
3.88
i)
0.00833
6.68
3.885
0.0083294
4) Write the following decimal numbers in scientific notation. Keep the same number of significant digits as already in
the number.
a) 4490000 4.49 x 106
b) 0.0002200 2.200 x 10−4
c) 3000000 3 x 106
5) Write the following scientific notation numbers in decimal form. Keep the same number of significant digits as already
in the number.
a) 3.2 x 10−5 0.000032
b) 9.254 x 10−3 0.009254
c) 2.95 x 106 2950000
6) What are the 5 fundamental measurements, and their base unit, that you are responsible for?
MEASUREMENT
BASE UNIT
length
meter
mass
kilogram
time
second
temperature
Kelvin
amount of substance
mole
-27) Indicate what metric prefix is used for the following powers of 10.
d) 103 kilo
g) 10−6 micro
b) 10−3 milli
e) 109 giga
h) 10−2 centi
c) 10−9 nano
f)
a) 106
mega
10−1 deci
i)
10−12 pico
8) Give the abbreviation for the following metric units.
a) kilometer
km
d) milligram
mg
g) megaliter
ML
b) gigasecond
Gs
e) decimeter
dm
h) nanosecond
ns
c) micrometer
μm
f)
cg
i)
pm
centigram
picometer
9) Compute the following addition and subtraction calculations. Round off answers to the correct number of significant
digits and label the answer with the correct unit.
a)
5.432 cm
2.52 cm
+ 1.6 cm
9.552 cm
9.6 cm
b)
d) 5000 cm + 0.123 cm + 2.1 cm =
5002.223 cm
5000 cm
7.136 mL
0.02 mL
+ 0.0032 mL
7.1592 mL
7.16 mL
e) 125.7 g ─ 32.62 g = 93.08 g
c)
47.892 m
─ 4.2 m
43.692 m
43.7 m
f)
6000. mL ─ 0.2 mL = 5999.8 mL
93.1 g
6000. mL
10) Compute the following multiplication and division calculations. Round off answers to the correct number of significant
digits and label the answer with the correct unit.
a) (0.063 cm)(0.063 cm) = 0.003969 cm2 = 0.0040 cm2
b) (32.31 m)(0.043 m) = 1.38933 m2 = 1.4 m2
c) (270 cm)(3.04 cm) = 820.8 cm2 = 820 cm2
d) (121 m)(0.32 m)(2 m) = 77.44 m3 = 80 m3
e)
g)
54.2 g
61.21 mL
200. cm
20 s
g
g
= 0.885476229 mL
= 0.885 mL
= 10 cm
s
f)
h)
7.85 g
200.4 mL
g
g
= 0.039171656 mL
= 0.0392 mL
(32.0 m)(14 kg)
0.005689 h
= 78748.46194 m∙kg
= 79000 m∙kg
h
h
11) Compute the following and give the answer in the correct number of significant digits and unit label.
a)
321.0 cm + 40 cm
25.00 s
=
360 cm
25.00 s
= 14.4 cm
= 14 cm
s
s
b)
(35.0 g)(261.00 g + 0.255 g)
(150 mL + 37.5 mL)
= 48.12684211
g2
mL
g2
= 48 mL
=
(35.0 g)(261.26 g)
190 mL
-312) Perform the given metric conversions. Keep the number of significant digits the same for the answer as the original
quantity.
a) 150 g = 0.15 kg
i)
0.003450 L = 3.450 mL
b) 422.5 mL = 0.4225 L
j)
4.256 x 10−4 dg = 4.256 x 10−3 cg or 0.004256 cg
c) 0.0035 km = 3.5 m
k) 350,000,000 m = 0.35 Gm
d) 6.25 x 105 μg = 0.625 g or 6.25 x 10−1 g
l)
e) 2.50 m = 250. cm
m) 180 ps = 0.18 ns
f)
32.10 ns = 0.03210 μs
15 mmol = 0.015 mol
n) 4205000 cm = 42.05 km
g) 0.0150 Mm = 15.0 km
o) 86.000 dg = 8.6000 g
h) 55.35 cg = 553.5 mg
p) 0.54202 ks = 542020000 μs
13) Perform the following calculations using the rules for significant digits.
20̅ 0
b) + 185.41
̅̅̅̅̅̅̅̅̅̅̅̅̅̅
385.41
390
4000
40̅ 00
d) - 40.4
̅̅̅̅̅̅̅̅̅̅̅̅
3959.6
40̅ 00 = 4.0 x 103
3960.
f)
16.748
4.2
a)
+ 3.06
̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅̅
24.008
24.0
c)
4000
- 40.4
̅̅̅̅̅̅̅̅̅̅̅̅
3959.6
e)
4000̅
- 40.4
̅̅̅̅̅̅̅̅̅̅̅̅
3959.6
g) (4100)(40.4) = 165640 = 170000
i)
45.0
90.0
= 0.5 = 0.500
4000.0
- 40.4
̅̅̅̅̅̅̅̅̅̅̅̅̅
3959.6
3959.6
h) (4100.0)(40.4) = 165640 = 166000
j)
(20.20)(0.004)(150)
3030
= 0.004
14) Perform the following calculations and give your answers in scientific notation using significant digits.
a) (4.52 x 109) + (6.23 x 1010) = 6.682 x 1010
b) (8.3 x 108) – (7.34 x 107) = 7.566 x 108 = 7.6 x 108
= 6.68 x 1010
c) (5.320 x 106)(4.23 x 10−3) = 2.25036 x 104
= 2.25 x 104
d) (9.090 x 108) ÷ (4.1 x 10−10) = 2.21707317 x 1018
= 2.2 x 1018
15) Calculate the density of an object having a mass of 32.56 g and a volume of 12.4 cm 3.
𝑑𝑒𝑛𝑠𝑖𝑡𝑦 =
𝑚𝑎𝑠𝑠
32.56 𝑔
𝑔
𝒈
=
= 2.625806452𝑐𝑚3 = 𝟐. 𝟔𝟑 𝟑
𝒄𝒎
𝑣𝑜𝑙𝑢𝑚𝑒
12.4 𝑐𝑚3
16) What property of water and hexane was utilized in the bromide/iodide lab?
Solubility.
17) What color was the hexane layer if the following ion was present in the original solution?
a) iodide
pink (purple)
b) bromide
gold (orange)
c) chloride
clear
d) iodide and bromide
pink (purple)
18) What are the 3 steps of the chloride test? Tell what happens for each step is chloride is present.
-add AgNO3 → precipitate forms
-add NH4OH → precipitate clears
-add HNO3 → precipitate forms
19) What is the precipitate in the chloride test when AgNO3 is added to a solution containing chloride?
silver chloride (AgCl)
20) What ion gives off a gas when acid was added in the chloride test?
carbonate ion (CO32−)