APA Chemistry Fall Semester Review

Front

What is the electron configuration for Rubidium (Rb)?

Back

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹

Front

How do you calculate the mass of a compound from moles?

Back

Mass (g) = Moles × Molar Mass (g/mol). For CaO, Molar Mass = 40.08 (Ca) + 16.00 (O) = 56.08 g/mol. Thus, 1.6 moles × 56.08 g/mol = 89.728 g, rounded to 90 g.

Front

What indicates a chemical change?

Back

A chemical change is indicated by the production of gas, color change, temperature change, or formation of a precipitate. Example: Gas is produced when sodium mixes with water.

Front

What is the name of K₃PO₄?

Back

Potassium phosphate.

Front

How do you determine the number of protons in an element?

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The number of protons is equal to the atomic number of the element. For the element with isotopes given, the atomic number is 33.

Front

What is the molar mass of CaO?

Back

Molar mass of CaO = 40.08 g/mol (Ca) + 16.00 g/mol (O) = 56.08 g/mol.

Front

What is the significance of isotopes in chemistry?

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Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons, affecting their mass.

Front

What is a physical change?

Back

A physical change is a change that does not alter the chemical composition of a substance, such as melting or boiling.

Front

What is the difference between a chemical change and a physical change?

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A chemical change results in the formation of new substances, while a physical change does not change the substance's chemical identity.

Front

What is the formula for calculating the number of moles?

Back

Number of moles = Mass (g) / Molar Mass (g/mol).