Carbonic acid (H₂CO₃) is diprotic acid. Draw the Lewis dot structure of carbonic acid and tell whether it is polar or not. (place the polarity here) If a 36.4 g piece of Iron (III) carbonate (Molar Mass = 291.72 g/mole) is dropped into a large excess of hydrochloric acid how many liters of carbon dioxide (at STP) are produced. Enter your answer with two decimal places.
The Correct Answer and Explanation is :
Solution:
1. Lewis Dot Structure of Carbonic Acid (H₂CO₃)
Carbonic acid is composed of one carbon atom, two oxygen atoms (double-bonded to carbon), one oxygen atom (single-bonded to carbon), and two hydrogen atoms bonded to the singly-bonded oxygen. The Lewis structure shows:
- Carbon (C) is the central atom.
- One oxygen is doubly bonded to carbon.
- One oxygen is singly bonded to carbon and also bonded to a hydrogen atom.
- The third oxygen is singly bonded to carbon and also bonded to the other hydrogen atom.
Polarity:
Carbonic acid is polar because it has polar bonds (C=O and O-H bonds) and an asymmetrical shape, causing a net dipole moment.
2. Calculating CO₂ Produced
Step 1: Write the reaction.
The reaction between Iron (III) carbonate (Fe₂(CO₃)₃) and hydrochloric acid (HCl) produces iron (III) chloride, water, and carbon dioxide:
[
Fe_2(CO_3)_3 + 6HCl \rightarrow 2FeCl_3 + 3CO_2 + 3H_2O
]
Step 2: Moles of Fe₂(CO₃)₃.
[
\text{Moles of } Fe_2(CO_3)_3 = \frac{\text{Mass}}{\text{Molar Mass}} = \frac{36.4 \, \text{g}}{291.72 \, \text{g/mol}} = 0.1247 \, \text{mol}
]
Step 3: Moles of CO₂ produced.
From the reaction, 1 mole of Fe₂(CO₃)₃ produces 3 moles of CO₂:
[
\text{Moles of CO}_2 = 0.1247 \, \text{mol} \times 3 = 0.3741 \, \text{mol}
]
Step 4: Volume of CO₂ at STP.
At STP, 1 mole of any gas occupies 22.4 L. Thus:
[
\text{Volume of CO}_2 = 0.3741 \, \text{mol} \times 22.4 \, \text{L/mol} = 8.38 \, \text{L}
]
Answer:
- Polarity: Polar
- Volume of CO₂: 8.38 L
Explanation:
Carbonic acid is a diprotic acid that can donate two protons due to the presence of two -OH groups. The asymmetry in its structure makes it polar. In the reaction, Fe₂(CO₃)₃ reacts with HCl, releasing CO₂ as a gas. The stoichiometric calculation considers the molar ratio and the gas law at STP, providing the volume with high accuracy.