Multiple Choice
Which set of coefficients correctly balances the chemical equation: __C_2H_6 + __O_2 → __CO_2 + __H_2O?
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3. Chemical Reactions
Balancing Chemical Equations
Multiple Choice
Which of the following is the correctly balanced chemical equation for the dissolution of CaCO3 in water?
A
CaCO3 (s) + H2O (l) → Ca(OH)2 (aq) + CO2 (g)
B
CaCO3 (aq) → Ca^{2+} (aq) + CO2 (g) + H2O (l)
C
CaCO3 (s) → Ca (s) + CO3 (g)
D
CaCO3 (s) → Ca^{2+} (aq) + CO3^{2-} (aq)
Verified step by step guidance1
Step 1: Understand the process of dissolution for ionic compounds like calcium carbonate (CaCO3). When CaCO3 dissolves in water, it dissociates into its constituent ions rather than forming new compounds or gases directly.
Step 2: Write the general dissociation equation for CaCO3 dissolving in water, which involves solid CaCO3 separating into calcium ions (Ca^{2+}) and carbonate ions (CO3^{2-}) in aqueous solution.
Step 3: Check the physical states of each species to ensure they are correctly represented: CaCO3 is a solid (s), and the ions Ca^{2+} and CO3^{2-} are aqueous (aq) because they are dissolved in water.
Step 4: Verify that the equation is balanced in terms of both atoms and charge. On the left, CaCO3 is neutral; on the right, Ca^{2+} has a +2 charge and CO3^{2-} has a -2 charge, so the charges balance out to zero overall.
Step 5: Confirm that no extra water molecules or gases are produced or consumed in the dissolution process, as dissolution typically involves only the solid and its ions in solution.
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