Download (density = 19.3 g/cm 3 ).

Chapter
1
COURSE NAME: CHEMISTRY 101
COURSE CODE: 402101-4
Chapter 1
2
International System of Units (SI)
Science problem solving requires both: 
Metric system —
English system —
3
4
Volume – SI derived unit for volume is cubic meter (m3)
1 cm3 = (1 x 10-2 m)3 = 1 x 10-6 m3
1 dm3 = (1 x 10-1 m)3 = 1 x 10-3 m3
1 L = 1000 mL = 1000 cm3 = 1 dm3
1 mL = 1 cm3
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Density – SI derived unit for density is kg/m3
1 g/cm3 = 1 g/mL = 1000 kg/m3
density =
mass
volume
m
d= V
A piece of platinum metal with a density of 21.5 g/cm3
has a volume of 4.49 cm3. What is its mass?
m
d= V
m=dxV
= 21.5 g/cm3 x 4.49 cm3 = 96.5 g
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A Comparison of Temperature Scales
K = 0C + 273.15
273 K = 0 0C
373 K = 100 0C
0F
=9
5
x 0C + 32
32 0F = 0 0C
212 0F = 100 0C
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6
Convert 172.9 0F to degrees Celsius.
=9 x 0C + 32
5
0F – 32 = 9 x 0C
5
0F
5
9
x (0F – 32) = 0C
=5 x (0F – 32)
9
5x (172.9 – 32) = 78.3
0C =
9
0C
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Scientific Notation
The number of atoms in 12 g of carbon:
602,200,000,000,000,000,000,000
6.022 x 1023
The mass of a single carbon atom in grams:
0.0000000000000000000000199
1.99 x 10-23
N x 10n
N is a number
between 1 and 10
n is a positive or
negative integer
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Significant Figures
Any digit that is not zero is significant•
1.234 kg
4 significant figures
Zeros between nonzero digits are significant•
606 m
3 significant figures
Zeros to the left of the first nonzero digit are not significant•
0.08 L
1 significant figure
If a number is greater than 1, then all zeros to the right of the decimal point are •
significant
2.0 mg
2 significant figures
If a number is less than 1, then only the zeros that are at the end and in the middle of •
the number are significant
0.00420 g 3 significant figures
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How many significant figures are in each
of the following measurements?
24 mL
2 significant figures
3001 g
4 significant figures
0.0320 m3
3 significant figures
6.4 x 104 molecules
2 significant figures
560 kg
2 significant figures
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Significant Figures
Addition or Subtraction
The answer cannot have more digits to the right of the decimal
point than any of the original numbers.
89.332
+ 1.1
one significant figure after decimal point
90.432
round off to 90.4
3.70
-2.9133
0.7867
two significant figures after decimal point
round off to 0.79
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Significant Figures
Multiplication or Division
The number of significant figures in the result is set by the original number that has the
smallest number of significant figures
4.51 x 3.6666 = 16.536366
3 sig figs
round to
3 sig figs
6.8 ÷ 112.04 = 0.0606926
2 sig figs
= 16.5
round to
2 sig figs
= 0.061
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Significant Figures
Exact Numbers
Numbers from definitions or numbers of objects are considered
to have an infinite number of significant figures
The average of three measured lengths; 6.64, 6.68 and 6.70?
6.64 + 6.68 + 6.70
3
= 6.67333 = 6.67
Because 3 is an exact number
=7
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Accuracy – how close a measurement is to the true value
Precision – how close a set of measurements are to each other
accurate
&
precise
precise
but
not accurate
not accurate
&
not precise
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Dimensional Analysis Method of Solving Problems
Determine which unit conversion factor(s) are needed
Carry units through calculation
.1
.2
If all units cancel except for the desired unit(s), then the problem was solved
correctly.
.3
given quantity x conversion factor = desired quantity
given unit x
desired unit
= desired unit
given unit
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Dimensional Analysis Method of Solving Problems
How many mL are in 1.63 L?
Conversion Unit 1 L = 1000 mL
1.63 L x
1000 mL
1L
= 1630 mL
1.63 L x
1L
1000 mL
= 0.001630
L2
mL
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Question 1
Question 3
Which of the following is an example of a physical property?
A) combustibility
Convert 240 K and 468 K to the Celsius scale.
A) 513oC and 741oC
B) corrosiveness
C) explosiveness
D) density
E) A and D
Question 2
Which of the following represents the greatest mass?
A) 2.0 x 103 mg
B) 10.0 dg
B) -59oC and 351oC
C) -18.3oC and 108oC
D) -33oC and 195oC
Question 4
Calculate the volume occupied by 4.50 X 102 g of
gold (density = 19.3 g/cm3).
A) 23.3 cm3
C) 0.0010 kg
D) 1.0 x 106 μg
E) 3.0 x 1012 pg
B) 8.69 x 103 cm
C) 19.3 cm3
D) 450 cm3
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Question 5
Question 7
The melting point of bromine is -7oC. What
is this melting point expressed in oF?
A) 45oF
How many significant figures should you
report as the sum of 8.3801 + 2.57?
A) 3
B) -28oF
B) 5
C) -13oF
C) 7
D) 19oF
D) 6
E) None of these is within 3oF
of the correct answer.
E) 4
Question 6
How many significant figures are there in
the measurement 3.4080 g?
A) 6
B) 5
C) 4
D) 3
E) 2
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Question 8
Walking fast can consume 5.0 kcal per minute. How many
hours of exercise are required to consume 450 kcal, the
energy in a large candy bar?
A) 7.5 hr
Question 10
A bar of gold is measured with the ruler shown. The
length of the bar should be reported as:
A) 3 cm
B) 1.25 hr
C) 1.75 hr
B) 3.0 cm
D) 1.5 hr
C) 2.7 cm
D) 2 cm
E) 1 hr
Question 9
Together, Americans drive about 5.0 x 109 miles per day,
and their cars get an average of 22 miles per gallon of gas
used. For each kilogram of gasoline used, about 3 kg of
carbon dioxide is produced. How many kilograms of CO2
are emitted into the atmosphere by cars in the US each
day? [1 gal = 3.5 kg]
A) 2 x 109 kg
B) 2.4 x 109 kg
C) 8.3 x 109 kg
D) 1.6 x 109 kg
E) None of the above
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Question 14
What is the SI unit of mass?
A) Meter
B) Centimeter
C) Gram
D) Kilogram (kg)
Question 15
Which is a useful equivalent?
A) 1 liter = 1 decimeter cubed
B) 1 meter = 1 centimeter cubed
C) 1 cubic centimeter = 1 cubic
decimeter
D) 1 kilogram = 1 liter
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Question 16
Question 18
Which of the following is true about the scientific method?
A) A hypothesis is a set of observations that are
explained by an experiment.
A 9.4-g sample of powdered titanium was added to a
graduated cylinder originally containing 6.8 mL of
water. After addition of the titanium, the water level in
the graduated cylinder was 8.9 mL. What is the density
of titanium?
A) 1.4 g/cm3
B) Researchers design experiments to prove the
conclusions they have already reached.
C) The purpose of performing an experiment is
to confirm or contradict a hypothesis.
D) To be useful, data must be qualitative.
E) Quantitative data are usually in the form of
descriptive observations.
B) 4.5 g/cm3
C) 1.1 g/cm3
D) 0.22 g/cm3
Question 17
Question 19
Which of the following is not an example of a mixture?
A) iced tea
At one atmosphere pressure, mercury solidifies at -38.0
oF. Express this temperature in degrees Celsius and
Kelvin.
A) -126 oC and 147 K
B) distilled water
C) mashed potatoes
D) vegetable soup
B) -39 oC and 234 K
E) tomato juice
C) -21 oC and 252 K
D) 39 oC and 312 K
E) -68 oC and 205 K
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Question 20
Question 22
How many significant figures are there in the number
0.0203610 g?
A) 8
A laboratory technician analyzed a sample three times for
percent iron and got the following results: 22.43% Fe, 24.98%
Fe, and 21.02% Fe. The actual percent iron in the sample was
22.81%. The analyst's
A) precision was poor but the average result was
accurate.
B) 7
C) 6
D) 5
B) accuracy was poor but the precision was
good.
C) work was only qualitative.
D) work was precise.
Question 21
A sample of a liquid has a density of 2.1 g/mL. What
volume of the liquid has a mass of 4.242 g?
A) 8.9 mL
B) 2.0 mL
C) 2.02 mL
D) 2.020 mL
E) 0.50 mL
E) C and D.
Question 23
The density of magnesium is 1.7 g/cm3, and the density of iron
is 7.9 g/cm3. Consider a block of iron with a mass of 819 g.
What is the mass of a block of magnesium that has the same
volume as the block of iron?
A) 1.8 x 102 g
B) 61 g
C) 2.8 x 103 g
D) 3.8 x 103 g
E) None of the above.
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Question 24
Which of the following is
a measurement of mass in
the metric system? A)
Celsius B) centimeter C)
milliliter D) kilogram
E) meter A
26.
The recommended daily allowance (RDA) of calcium is 1200 mg.
Calcium carbonate contains 12% calcium by mass. How many grams of
calcium carbonate are needed to provide the RDA of calcium?
A) 1.3 g
B) 1.4 g
C) 0.14 g
D) 10. g
27. A value of 25˚C is a
measurement of A) density.
B) distance. C) mass. D)
volume. E) temperature.
E) 0.19 g
Question 25
Table salt (sodium chloride) is 42.7% sodium. How many grams of salt
contain 76.0 g of sodium?
A) 32.5 g
B) 178 g
C) 3.25 x 103 g
28. A value of 36 mL is a
measure of A) distance
B) density C) temperature
E) volume
D) mass
D) 1.78 g
E) 1.78 x 104 g
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29. value of 345 mm is a measure of
A) temperature B) density C) volume
D) distance E) mass
30. The measurement 0.000 004 3 m,
expressed correctly using scientific
notation, is
A) 0.43 x 10-5 m B) 4.3 x 10-6
C) 4.3 x 10-7
D) 4.3 x 10-5
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