Significant figures
What is represented by the following prefixes:
a) mega-
b) kilo-
c) deci-
d) centi-
a) 1 × 10^ 6
b) 1 × 10^3
c) 1 × 10^−1
d) 1 × 10^−2
What mass of helium contains the same number of atoms as 55.63g of mercury?
1.110g He
What is the density of an object that has a volume of 69.5cm3 and a mass of 121g
1.74 g/cm3
The argon in nature consists of three isotopes: 126I, 125I, and 127I. Which of the following
statements is TRUE
(A) All three isotopes exist in nearly equal quantities.
(B) 126I is the most abundant isotope.
(C) 125I is the most abundant isotope.
(D) 127I is the most abundant isotope.
(E) All of the isotopes are extremely radioactive and decay quickly into other stable elements.
D
Convert 0.00456 kilograms to grams. How many significant figures should your answer have?
3
How many Zn atoms are in 545g of Zn?
5.02 X 1024 atoms
Convert a density of 16.2 g/mL to kg/µm3
1.62 X 10-14 kg/µm3
Write the nuclide symbol for an atom that contains 80 protons and 120 neutrons
200Hg
Multiply 5.6 × 10³ by 0.00456. How many significant figures should your result have?
2
Arrange the following in order of increasing mass:
i: 1.85 X 1024 Fe atoms
ii: 7.68X 1023Ba atoms
iii: 9.68 X 1023 Pd atoms
iv: 1.22 X 1024 Kr atoms
Ice cubes float in a glass of water because solid water is less dense than liquid water.
a) calculate the density of ice given that at 0oC, a cube that is 2.0 cm on each side has a mass of 7.36g
b) determine the volume occupied by 23g of ice at 0oC.
a) d= 0.92 g/cm3 or 0.92 g/mL
b) V= 25cm3 or 25mL
The atomic masses of the two stable isotopes of copper 6329Cu (69.17%) and 6529Cu (30.83%), are 62.929599 and 64.927793 amu, respectively. Calculate the average atomic mass of copper.
63.55amu
Add 123.45 and 0.0023, then multiply the result by 0.100. How many significant figures should the final answer have?
3
One container holds a mixture of metals containing 72.09g of sodium and 6.99g of strontium. Another container holds 47.87g of titanium. What mass of calcium would have to be added to the second container for it to hold the same number of atoms as the first container?
88.80g
Given that 20.0mL of mercury has a mass of 272g, calculate
a) The density of mercury
b) The volume of 748g of mercury.
a) 13.6 g/mL
b) 55.0mL
A piece of metal weighing 345986.0 mg is placed in a graduated cylinder containing 296.1 mL of water. The volume of the water rises to 327.0 mL. What is the density of the metal in g/cm3 ?
11.2 g/cm3
Bromine has two naturally occurring isotopes, 79Br 81Br, which have masses 78.92 and 80.92 amu, respectively. given the average atomic mass of bromine (79.90 amu) deter the percent abundance of each isotope.
79Br: 51%
81Br: 49%
The distance from Charlotte to New York is 8.45 × 109 mi. If sound travels at a speed
of 340 m/s, how many minutes does it take for a sound wave to travel from Charlotte to new York?
1.00 mi = 1.60934 km
6.7 X 108 mins
Given that the density of gold is 19.3g/cm3, calculate the volume (in cm3) of a gold nugget with a mass of 5.98g.
0.310cm3
The average atomic mass of nitrogen is 14.0067. the atomic masses of the two stable isotopes of nitrogen, 14N and 15N, are 14.003074002 and 15.000108898 amu, respectively. Use this information to determine the percent abundance of each nitrogen isotope.
14N: 99.64%
15N: 0.36%