Rio Salado CHM 130 Midterm Objectives
with Complete Solutions
What is the definition of an element in chemistry?
✔✔ An element is a pure substance consisting of only one type of atom.
How is a compound different from a mixture?
✔✔ A compound is a substance composed of two or more different elements chemically
combined, while a mixture is a combination of two or more substances that are not chemically
bonded.
What does the term “molarity” refer to in chemistry?
✔✔ Molarity refers to the concentration of a solution, specifically the number of moles of solute
per liter of solution.
What is an ionic bond?
✔✔ An ionic bond is a chemical bond formed through the transfer of electrons from one atom to
another, resulting in the attraction between positively and negatively charged ions.
1
,What is the difference between an exothermic and an endothermic reaction?
✔✔ An exothermic reaction releases heat to the surroundings, while an endothermic reaction
absorbs heat from the surroundings.
What is the role of a catalyst in a chemical reaction?
✔✔ A catalyst speeds up a chemical reaction by lowering the activation energy required without
being consumed in the process.
How do you determine the empirical formula of a compound?
✔✔ The empirical formula is determined by finding the simplest whole-number ratio of the
elements in the compound.
What is the principle of conservation of mass?
✔✔ The principle of conservation of mass states that mass cannot be created or destroyed in a
chemical reaction; it remains constant.
What is a mole in terms of chemistry?
✔✔ A mole is a unit that represents \(6.022 \times 10^{23}\) particles (atoms, molecules, ions,
etc.) of a substance.
2
, What does the term “oxidation state” refer to?
✔✔ The oxidation state refers to the charge of an atom within a compound, indicating the
number of electrons lost or gained.
What is the difference between a physical change and a chemical change?
✔✔ A physical change affects only the physical properties of a substance without altering its
chemical composition, while a chemical change results in the formation of one or more new
substances with different chemical properties.
How is the atomic number of an element defined?
✔✔ The atomic number of an element is the number of protons in the nucleus of an atom of that
element.
What is a chemical reaction?
✔✔ A chemical reaction is a process in which substances, called reactants, are transformed into
new substances, called products, with different chemical properties.
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with Complete Solutions
What is the definition of an element in chemistry?
✔✔ An element is a pure substance consisting of only one type of atom.
How is a compound different from a mixture?
✔✔ A compound is a substance composed of two or more different elements chemically
combined, while a mixture is a combination of two or more substances that are not chemically
bonded.
What does the term “molarity” refer to in chemistry?
✔✔ Molarity refers to the concentration of a solution, specifically the number of moles of solute
per liter of solution.
What is an ionic bond?
✔✔ An ionic bond is a chemical bond formed through the transfer of electrons from one atom to
another, resulting in the attraction between positively and negatively charged ions.
1
,What is the difference between an exothermic and an endothermic reaction?
✔✔ An exothermic reaction releases heat to the surroundings, while an endothermic reaction
absorbs heat from the surroundings.
What is the role of a catalyst in a chemical reaction?
✔✔ A catalyst speeds up a chemical reaction by lowering the activation energy required without
being consumed in the process.
How do you determine the empirical formula of a compound?
✔✔ The empirical formula is determined by finding the simplest whole-number ratio of the
elements in the compound.
What is the principle of conservation of mass?
✔✔ The principle of conservation of mass states that mass cannot be created or destroyed in a
chemical reaction; it remains constant.
What is a mole in terms of chemistry?
✔✔ A mole is a unit that represents \(6.022 \times 10^{23}\) particles (atoms, molecules, ions,
etc.) of a substance.
2
, What does the term “oxidation state” refer to?
✔✔ The oxidation state refers to the charge of an atom within a compound, indicating the
number of electrons lost or gained.
What is the difference between a physical change and a chemical change?
✔✔ A physical change affects only the physical properties of a substance without altering its
chemical composition, while a chemical change results in the formation of one or more new
substances with different chemical properties.
How is the atomic number of an element defined?
✔✔ The atomic number of an element is the number of protons in the nucleus of an atom of that
element.
What is a chemical reaction?
✔✔ A chemical reaction is a process in which substances, called reactants, are transformed into
new substances, called products, with different chemical properties.
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