Multiple Choice
Consider the balanced equation for the combustion of heptane: C7H16(g) + 11 O2(g) → 7 CO2(g) + 8 H2O(g). How many moles of O2 are required to react completely with 4.8 moles of C7H16?
3. Chemical Reactions
Balancing Chemical Equations
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Which of the following is the balanced molecular equation for the reaction between nitric acid (HNO3) and magnesium hydroxide (Mg(OH)2)?
A
2 HNO3 + Mg(OH)2 → Mg(NO3)2 + H2
B
2 HNO3 + Mg(OH)2 → Mg(NO3)2 + 2 H2O
C
HNO3 + Mg(OH)2 → Mg(NO3)2 + H2O
D
HNO3 + Mg(OH)2 → Mg(NO3)2 + 2 H2O
Verified step by step guidance1
Identify the reactants and products in the chemical reaction. The reactants are nitric acid (HNO3) and magnesium hydroxide (Mg(OH)2), and the products are magnesium nitrate (Mg(NO3)2) and water (H2O).
Write the unbalanced chemical equation: HNO3 + Mg(OH)2 → Mg(NO3)2 + H2O.
Balance the equation by ensuring the number of atoms of each element is the same on both sides. Start by balancing the magnesium (Mg) atoms. There is one Mg atom on each side, so they are balanced.
Next, balance the nitrate ions (NO3). There are two nitrate ions in Mg(NO3)2, so you need two HNO3 molecules on the reactant side: 2 HNO3 + Mg(OH)2 → Mg(NO3)2 + H2O.
Finally, balance the hydrogen (H) and oxygen (O) atoms. There are four hydrogen atoms in 2 HNO3 and two in Mg(OH)2, making a total of six hydrogen atoms. To balance, you need three water molecules on the product side: 2 HNO3 + Mg(OH)2 → Mg(NO3)2 + 2 H2O.
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