Multiple Choice
Which of the following is the correct chemical formula for magnesium nitrate?
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3. Chemical Reactions
Naming Ionic Compounds
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Which of the following is the correct chemical formula for chromium(III) oxide?
A
Cr3O2
B
Cr2O3
C
CrO3
D
CrO2
Verified step by step guidance1
Identify the oxidation state of chromium in chromium(III) oxide. The Roman numeral III indicates that chromium has a +3 charge, so Cr is Cr^{3+}.
Determine the charge of the oxide ion. Oxygen typically forms an oxide ion with a charge of O^{2-}.
Balance the total positive and negative charges to find the correct ratio of chromium to oxygen atoms. Let the number of chromium ions be x and oxygen ions be y, so the total charge is x(3+) + y(2-) = 0.
Set up the equation: 3x = 2y, which means the ratio of chromium to oxygen atoms must be 2:3 to balance the charges.
Write the chemical formula using the ratio found: Cr_2O_3, which corresponds to the compound chromium(III) oxide.
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