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WorksheetsMatter- Matriculation Level
Total questions: 22
Worksheet time: 11mins
One proper way to indicate an isotope of Si with an atomic mass of 28 is
28-Si
Si-28
28Si
Si28
The atomic mass of an element is defined as the weighted average mass of that elements
naturally occurring isotopes
least abundant isotope
radioactive isotopes
most abundant isotope
Average atomic mass is calculated from
atomic mass and atomic number
average of isotope masses
atomic masses and abundance of isotopes
relative abundance of isotopes
A sample of element X contains 90% X-35 atoms, 8.0% X-37 atoms, and 2.0% X-38 atoms. The average atomic mass will be closest to which value?
35
36
37
38
The atomic masses in the periodic table are not integral numbers. For example, carbon is listed as 12.01115 instead of 12.00000. Choose the most appropriate explanation.
There is a theoretical uncertainty in the masses of atom.
Atoms gain and lose electron easily and that changes their masses significantly.
Atomic masses listed in the periodic table are weighted averages of naturally occurring isotopes.
Atomic masses are measured in real samples that are always contaminated with other elements.
Which term is described as the lowest whole-number ratio of elements in a compound?
molecular formula
hydrate
percent composition
empirical formula
When are as empirical formula and a molecular formula the same?
Always
When the mass of the empirical formula unit is equal to the molecular mass
When the mass percentages of all of the elements in the two formula are the same
When the molecular mass is an integer multiple of formula unit mass
Which of the following represent a molecular formula and its empirical formula?
Molecular formula Empirical formula
CH4 CH2
C2H6 CH3
C2H4 C4H8
C8H3 (CH)2
Which of the following is NOT a true statement concerning empirical and molecular Formula?
The molecular formula of a compound can be some whole number multiple of
its empirical formula.
Several compounds can have the same empirical formula, but have different molecular formulas.
The molecular formula of a compound can be the same as its empirical formula.
The empirical formula of a compound can be triple its molecular formula.
What is the definition for molarity?
Grams of solute per moles of solute
Moles of solute per grams of solution
Moles of solute per Liter of solvent
Moles of solute per Liter of solution
What is the definition for mass percent solute?
(grams of solute / grams of solvent) times 100%
(grams of solvent / grams of solute) times 100%
(moles of solute / moles of solvent) times 100%
(grams of solute / grams of solution) times 100%
Which of the following concentration terms below represents moles of solute per kilogram of solvent?
Molarity
Molality
Mole fraction
Mole percent
What is the study of the mass relationships among reactants and products in a chemical reaction?
reaction stoichiometry
electron configuration
composition stoichiometry
periodic law
Which of the following would not be studied in the branch of chemistry called stoichiometry?
the mole ratio of aluminum and chlorine in aluminum chloride
the amount of energy required to break the ionic bonds in calcium fluoride
the mass of carbon produced when a known mass of sucrose decomposes
the number of moles of hydrogen that reacts completely with a known quantity of oxygen
To balance a chemical equation, it may be necessary to adjust the
coefficients
formulas of the products
subscripts
number of products
A balanced chemical equation allows one to determine the
mole ratio of any two substances in the reaction.
energy released in the reaction.
electron configuration of all elements in the reaction.
mechanism involved in the reaction.
If one knows the mole ratio of a reactant and product in a chemical reaction, one can
estimate the energy released in the reaction
calculate the speed of the reaction
calculate the mass of the product produced from a known mass of reactant
decide whether the reaction is reversible
To determine the limiting reactant in a chemical reaction involving known masses of A and B, one could first calculate
the mass of 100 mol of A and B
the masses of all products
the bond energies of A and B
the number moles of B and the number moles of A available
Which reactant controls the amount of product formed in a chemical reaction?
excess reactant
composition reactant
mole ratio
limiting reactant
What is the ratio of the actual yield to the theoretical yield, multiplied by 100%?
mole ratio
Avogadro yield
percentage yield
excess yield
In most chemical reactions the amount of product obtained is
equal to the theoretical yield
more than the theoretical yield.
less than the theoretical yield.
more than the percentage yield.
If the percentage yield is equal to 100%, then
the actual yield is greater than the theoretical yield
the actual yield is equal to the theoretical yield
the actual yield is less than the theoretical yield
there was no limiting reactant
