CHEM 101 - Exam 1
Determine the neutral formula unit for the compound formed from the ions NH+4 and CO2−3.
(NH4)2CO3
For each element, identify the charge of its most common ion. (Rb)
+1
What is the charge on a hypothetical ion with a 25 protons and 23 electrons
+2
For each element, identify the charge of its most common ion. (Al)
+3
A 9.97 g sample of calcium sulfide was decomposed into its constituent elements, producing 5.54 g of calcium and 4.43 g of sulfur. Which of the statements are consistent with the law of constant composition (definite proportions)? - The mass ratio of Ca to S in every sample of calcium sulfide is 1.25 - The ratio of calcium to sulfur will vary based on how the sample was prepared. - Every sample of calcium sulfide will have 5.54 g of calcium. - The mass percentage of calcium plus the mass percentage of sulfur in every sample of calcium sulfide equals 100%. - Every sample of calcium sulfide will have 55.6% mass of calcium.
- The mass ratio of Ca to S in every sample of calcium sulfide is 1.25 - The mass percentage of calcium plus the mass percentage of sulfur in every sample of calcium sulfide equals 100%. - Every sample of calcium sulfide will have 55.6% mass of calcium.
Arrange the statements made during a process to correspond with the scientific method - The instrument provides evidence that the sample is zinc - You use an instrument to identify elements in the shiny material - You notice a shiny metal speck in a rock - You suspect the tiny spect could be gold - You conclude that the material is zinc
- You notice a shiny metal speck in a rock - You suspect the tiny spect could be gold - You use an instrument to identify elements in the shiny material - The instrument provides evidence that the sample is zinc - You conclude that the sample is zinc
Physical properties
- melting point - boiling point - color - conductivity
Chemical properties
- susceptible to rust - flammability
For each element, identify the charge of its most common ion. Fluorine (F)
-1
For each element, identify the charge of its most common ion. (Se)
-2
Convert 6.91 mL to liters.
0.00691
How many protons are in an ion with 18 electrons and a -1 charge
17 Protons
identify the exact numbers: 3 lbs (the weight of an object measured on a scale) 2.54 cm (the number of centimeters in exactly 1 inch) 56.00 s (the time measured by a stopwatch) 4 choices (the number of choices in a list)
2.54 cm (the number of centimeters in exactly 1 inch) & 4 choices (the number of choices in a list)
Round each number to two significant figures. 233.356: 0.002353: 1.005:
233.356: 2.3x10^2 0.002353: 2.4x10^-3 1.005: 1.0
How many total electrons are in a Fe 2+ ion
24 electrons
Convert 264.9 °F to degrees Celsius.
264.9 °F = 129.4 °C
To how many significant figures should each answer be rounded? equation B: (6.022× 10^23 atoms/mol)(0.801 g)20.18 g/mol =2.390×1022 atoms(unrounded)
3 significant figures
To how many significant figures should each answer be rounded? equation A: (6.626× 10^−34 J⋅s)(2.9979× 10^8 m/s)/4.710×10^−7m =4.217427898089×10^−19 J(unrounded)
4 significant figures
The surface temperature on Mercury has been measured to be 425 K . What is this temperature in degrees Celsius?
425 K = 151.85°C
Convert 6.66 μm to inches.
6.66 μm = 0.0002622
Convert a temperature of 67.0 °C to kelvins.
67.0 °C = 340.15
Convert 9.72 km to centimeters.
972000
Which of the statements about hypotheses and theories is TRUE? A scientific theory summarizes a hypothesis that has been supported with repeated testing. To be called a hypothesis, an explanation must be tested by multiple independent researchers. A hypothesis always leads to a scientific theory. The scientific theory is established first followed by the hypothesis.
A scientific theory summarizes a hypothesis that has been supported with repeated testing.
Name the ionic compound Al2O3
Aluminum oxide
Which of the statements describes a chemical property? Water freezes at 0 ∘C. Iodine (a purple solid) becomes a purple gas. Helium is the lightest monatomic element. Antacid tablets neutralize stomach acid.
Antacid tablets neutralize stomach acid.
Determine the formula: barium phosphate
Ba3(PO4)2
One molecule of caffeine contains 8 atoms of carbon, 10 atoms of hydrogen, 4 atoms of nitrogen, and 2 atoms of oxygen. Write the formula
C8H10N4O2
Write the chemical formula for each compound described. calcium chloride (1Ca ion, 2Cl ions):
CaCl2
Name the ionic compound CaS
Calcium sulfide
CO
Carbon oxide
CoF2(s):
Cobalt(II) Fluoride
CuI(s):
Copper(I) Iodide
copper(I) oxide:
Cu2O
copper(I) bromide:
CuBr
copper(II) bromide:
CuBr2
copper(II) oxide:
CuO
Allotropes of carbon
Diamond fullerenes (buchminsterfullerene) graphite
Proton, neurons, and electrons ___________ have a relative charge of 1-
Electrons
A well-controlled procedure used to obtain data in order to describe a phenomenon.
Experiment
A valid explanation about some natural phenomena
Fact
Anions carry a positive charge.
False
The Cl− and Br− ions have the same number of electrons.
False
The Cu+ and Cu2+ ions have the same number of electrons.
False
When an atom gains an electron, it becomes a cation.
False
iron(III) oxide
Fe2O3
iron(III) oxide:
Fe2O3
iron(III) bromide:
FeBr3
hydrogen gas
H2
water
H2O
Hydrofluoric acid
HF
identify the elements that are diatomic
Hydrogen (H) Nitrogen (N) Oxygen (O) Chlorine (Cl) Fluorine (F) Bromine (Br) Iodine (I)
A statement that can be, but has yet to be, supported by experimental data.
Hypothesis
A tentative model or picture that offers an explanation for the behavior of a reaction
Hypothesis
FeO(s):
Iron(II) Oxide
Fe2O3(s):
Iron(III) Oxide
A generalization that concisely summarizes information about natural phenomena
Law
Write the chemical formula for each compound described. lithium sulfide (2Li ions, 1S ion):
Li2S
Name the ionic compound LiBr
Lithium bromide
Which best describes what happens when molecular compounds melt?
Molecules arranged in a regular pattern change to an irregular pattern.
Classify each of the compounds as molecules or salt NO2 C6H6 CaSO4 KI CH2O CaS
Molecules: NO2, CH2O, C6H6 salt: KI, CaSO4, CaS
A statement describing a natural phenomenon that humans sense.
Observation
lead(IV) bromide:
PbBr4
lead(IV) oxide:
PbO2
Name the ionic compound: K2O
Potassium oxide
Proton, neurons, and electrons __________ have a relative charge of 1+
Protons
A statement that is explained by reproducible experimental data.
Scientific fact
A statement that describes a natural phenomenon by summarizing collected facts.
Scientific law
Identify each transition in this flowchart as a chemical change or a physical change.
See attachment
Name the compound with the chemical formula: SrBr2
Strontium Bromide
Name the compound with the chemical formula: SrO
Strontium Oxide
Name the ionic compound SrCl2
Strontium chloride
SF2
Sulfur difluoride
Which one of the following statements a about scientific hypothesis is FALSE? - The previously known outcome of an observation or experiment can be used as solid proof that a newly-created scientific hypothesis is absolutely true. - A scientific hypothesis is an explanation for a natural phenomenon. - A scientific hypothesis is an educated guess about why something happens. - In order to be useful, a scientific hypothesis must be testable in a way that is replicable by other scientists.
The previously known outcome of an observation or experiment can be used as solid proof that a newly-created scientific hypothesis is absolutely true.
A tentative model that has been tested over and validated over long periods of time
Theory
A scientific theory summarizes a hypothesis that has been supported with repeated testing.
True
The Fe2+ and Fe3+ ions have the same number of protons.
True
The K+ ion is formed when a potassium atom loses one electron.
True
which of the items adopt neither the shape nor volume of its container helium in a balloon soda in a bottle coin in a plastic bag
coin in a plastic bag
Proton, neurons, and electrons _________ have a much lower mass than the other two types of particles
electrons
Label the zeros as significant or not significant in the number 0.020
first: not significant second: not significant third: significant
Which of these substances are elements? silicon lead silicone water quartz iodine
lead silicon iodine
Determine the classes of matter described by each question. Each question may describe more than one class of mater.
molecules arranged in a regular pattern change to an irregular pattern
Identify the power of ten that defines each of these prefixes. Input your answers as 10𝑥 where 𝑥 is the power of ten. nano - centi - milli - kilo - micro - mega -
nano - 10^-9 centi - 10^-2 milli - 10^-3 kilo - 10^3 micro -10^-6 mega - 10^6
Isotopes are atoms of a particular element that contain a different number of _________
neutrons
Proton, neurons, and electrons __________ have no charge
neutrons
Write the names of the metric system units given. Spelling counts. - ng: - mg: - pm: - μm:
ng: nanogram mg: milligram pm: picometer μm: micrometer
Proton, neurons, and electrons ___________ located in the nucleus of an atom
protons and neutrons
P4S3
tetraphosphorus trisulfide
P3N5
triphosphorus pentanitride
Which are examples of matter energy water heat air sound
water; air