Honors Chemistry
Unit 1 Review Guide
Name __________________________
Class _______ Date _______
Key Terms:
precision accuracy %error %difference significant figures mole density John Dalton JJ Thomson cathode ray tube
Ernest Rutherford gold foil exp. Robert Millikan
oil drop experiment conservation of mass
definite proportions multiple proportions
proton neutron electron ion atomic number mass number average atomic mass isotope mass spectrometer atomic mass unit
pure substance element compound heterogeneous homogeneous half-life emission spectrum
Equations:
%𝑒𝑟𝑟𝑜𝑟 =
|𝑦𝑜𝑢𝑟 𝑟𝑒𝑠𝑢𝑙𝑡−𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒|
𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒
average deviation =
c=λ∙ν
∑|𝑒𝑥𝑝.𝑣𝑎𝑙𝑢𝑒−𝑚𝑒𝑎𝑛|
Ephoton = h ∙ ν
ℎ = 6.626 × 10
1.
𝑁
−34
𝑚
× 100
𝑑= 𝑉
%deviation= 100(
h∙c
𝑎𝑣𝑒. 𝑑𝑒𝑣𝑖𝑎𝑡𝑖𝑜𝑛
) 𝑎𝑚𝑡. 𝑟𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 = (𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝑎𝑚𝑜𝑢𝑛𝑡)(1⁄2)𝑛
𝑚𝑒𝑎𝑛
−2.18x10−18 J
En=
Ephoton = λ
mav = %1m1 + %2m2 . . .
𝐽∙𝑠
n2
∆Eelectron = En-final – En-initial
5.
What is the %composition of water in the following hydrated
compound: CuSO4•7H2O?
6.
Ascorbic acid (vitamin C) is 40.92% C, 4.58% H and 54.50%
O by mass. What is the empirical formula of ascorbic acid?
7.
Caffeine contains by mass composition 49.5% C, 5.15% H,
28.9% N and 16.5 % O and the molar mass is about 195
g/mol.
8.
The structure of glucose is shown:
a. What is it’s chemical formula?
b. What is it’s molar mass?
c. How many molecules of glucose in 1.2 x 10-3 g?
9.
Identify the scientists:
a. ____________; elements made of indestructible,
identical atoms that combine to make compounds
b. ____________: identified cathode rays as electrons and
measured charge-to-mass ratio
c. ____________: measured electron charge with oil drops
in a vacuum chamber
d. ____________: characterized nucleus as dense and
positive with gold foil and alpha () radiation
e. ____________: characterized electron region in terms of
energy levels and concentric "orbits"
Look at each target and decide whether the “hits” are
accurate, precise, both accurate and precise, or neither
accurate nor precise: (Note: An accurate “hit” is a bulls eye!)
Accurate?: Yes / No
Precise?: Yes / No
Accurate?: Yes / No
Precise?: Yes / No
Accurate?: Yes / No
Precise?: Yes / No
2.
3.
A student adds 7.76 g of metal pellets to a graduated cylinder
containing 5.00 mL. The total volume of the pellets and
water is 7.87 mL. What is the density of the pellets? If the
actual density of the metal pellets is 2.30 g/mL, then what is
the %error?
Express the following with the correct sig. fig’s.
a.
b.
4.
992.0+1.01+6
71.4
(3.016)(4.23)
(0.0031)
=
=
10. To illustrate Robert Millikan’s determination of the charge on
an electron, suppose that you were given the task of
determining the mass of a single jelly bean given the
following experimental data: Various scoops of jelly beans
were weighed and the following masses determined. The
number of jelly beans in each scoop was not known.
Masses (in grams) of ten different scoops:
12.0 g of CO2 has a volume of 6.11 L.
a. What is the density of the CO2?
b.
What is the molar mass of CO2?
c.
How many moles of CO2?
d.
How many molecules of CO2?
4.96
8.68
13.64
7.44
21.08
16.12
9.92
19.84
6.20
12.40
11. Write the symbol for the following ions: Mg losing 2 e-, Al
losing 3 e-, N gaining 3 e-, S gaining 2 e-
19. A gaseous sample of chromium can be analyzed in a mass
spectrometer. Before deflection, the chromium atoms are
ionized and then accelerated.
a. Describe briefly how positive ions are formed from
gaseous chromium atoms in a mass spectrometer?
12. Which of the following atoms are isotopes of the same
element? Identify the elements of these isotopes and
describe the number of protons and neutrons in the nucleus
of them all.
15
18
16
12
13
14
14
13
17
7𝑋
6𝑋
7𝑋
8𝑋
7𝑋
6𝑋
8𝑋
6𝑋 8𝑋
b.
What is used in a mass spectrometer to accelerate the
positive ions?
c.
What is used to deflect the positive ions?
d.
13. Law of multiple proportions.
a. What is the mass ratio of oxygen to nitrogen in NO2?
O2 = _____N = ______
Oxygen/Nitrogen =_____ / _____ = _________
The mass spectrum of a sample of chromium shows four
peaks. Use the data below to calculate the relative
mass of chromium in the sample.
m/z
50
52
53
54
relative
4.3
83.8
9.5
2.4
abundance %
b. In NO, what is the mass ratio?
O = ______N = ______
Oxygen/Nitrogen =_____ / _____ = _________
The multiple of the mass ratios is______ / ______=______
20. Use the mass spectrograph to calculate the average atomic
mass of zirconium
14. The mass ratio of sodium to fluorine in sodium fluoride is
1.21:1. A sample of sodium fluoride produced 28.8 g of
sodium upon decomposition. How much fluorine in grams
was formed? What’s the name of this law?
relative
abundance %
H+,
15. Place the forms of hydrogen (H,
Atom
Cation
Anion
H- ,
51.5
H2) in the table.
Molecule
17.4
5
17.1
11.2
16.
2.8
Particle
proton
neutron
electron
Location
Charge
Mass
Symbol
88
b.
90 91
92
93 94 95 96
mass/charge
(m/z)
17. If copper is a mixture of two isotopes, Cu-63, mass=62.93 u
and Cu-65 mass=64.93 u. The average mass of copper is
63.55 u. Calculate the % abundances of the two isotopes of
copper.
25
18. Magnesium has two common isotopes 24
12𝑀𝑔 , 12𝑀𝑔
a. How many protons, electrons & neutrons are in
89
25
2+
12𝑀𝑔
21. Classify each change as physical or chemical.
?
What is the average atomic mass if the abundance of Mg24 is 70.0 %?
22. The half-life of francium is 21 minutes. Starting with 4.0x1018
atoms of francium, how many atoms would disintegrate in
1 hour and 45 minutes? What fraction of the original sample
remains?
23. Selenium-83 has a half-life of 25.0 minutes. How many
minutes would it take for a 10.0 mg sample to decay and
have only 0.3125 mg of it remain?
24. Element-106 has a half-life of 0.90 seconds. If one million
atoms of it were prepared, how many atoms would remain
after 4.5 seconds?
25. A lab group conducted 5 trials to measure the density of lead
with the following data: 11.10 g/cm3, 11.59 g/cm3, 11.63
g/cm3, and 10.58 g/cm3.
Determine the following:
a. mean
b.
average deviation
c.
percent deviation
26. Complete the chart.
mass
molar mass
# moles
#atoms, molecules
2.50 g NH3
0.50 moles Fe atoms
1.85x1024 molecules CO2