Multiple Choice
Which of the following is the correct chemical formula for copper(II) oxide?
3. Chemical Reactions
Naming Ionic Compounds
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Which of the following is the correct chemical formula for potassium oxide?
A
KO2
B
K3O
C
K2O
D
K2O2
Verified step by step guidance1
Understand that potassium oxide is a compound formed between potassium (K) and oxygen (O). Potassium is an alkali metal with a charge of +1 as an ion (K⁺), and oxygen typically forms an oxide ion with a charge of -2 (O²⁻).
To write the correct chemical formula, balance the total positive and negative charges so that the compound is electrically neutral. Since potassium has a +1 charge and oxygen has a -2 charge, determine the ratio of potassium ions to oxide ions needed to balance the charges.
Set up the charge balance equation: Let the number of potassium ions be x and the number of oxide ions be y. The total positive charge is +1 * x and the total negative charge is -2 * y. For neutrality, +1 * x + (-2) * y = 0.
Solve the equation for the smallest whole number ratio: x = 2 and y = 1, meaning two potassium ions balance one oxide ion. This gives the formula K₂O.
Compare this formula to the options given. K₂O matches the correct charge balance and is the correct chemical formula for potassium oxide.
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