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Complete combustion of 0.0100 mol of an organic acid produced 0.0200 mol of carbon dioxide - AQA - A-Level Chemistry - Question 7 - 2022 - Paper 3
Question 7
Complete combustion of 0.0100 mol of an organic acid produced 0.0200 mol of carbon dioxide. The same amount of the acid required 20 cm³ of 1.00 mol dm⁻³ NaOH (aq) f... show full transcript
Worked Solution & Example Answer:Complete combustion of 0.0100 mol of an organic acid produced 0.0200 mol of carbon dioxide - AQA - A-Level Chemistry - Question 7 - 2022 - Paper 3
Step 1
Calculate moles of the acid
Answer
From the balanced equation for the combustion of the acid, we know that the production of carbon dioxide indicates the number of moles of the acid.
Given that 0.0200 mol of carbon dioxide is produced from the complete combustion of 0.0100 mol of the organic acid, we can establish that:
Thus, 0.0100 mol of the acid yields 0.0200 mol of CO₂.
Step 2
Analyze the neutralization reaction
Answer
The amount of NaOH that reacts is 20 cm³ of 1.00 mol dm⁻³ NaOH.
To convert this volume to moles, use the formula:
[ \text{moles of NaOH} = \text{concentration (mol/dm}^3) \times ext{volume (dm}^3) ]
[ = 1.00 \times 0.020 = 0.020 \text{ mol} ]
This indicates that 0.020 mol of NaOH is required to neutralize the organic acid.
Step 3
Determine possible acid formulas
Answer
Given that the organic acid reacts with NaOH in a 1:1 ratio and that 0.0100 mol of acid is used, we should consider the formulas provided in the options:
- A) HCOOH
- B) CH₃COOH
- C) HOOCCCOOH
- D) HOOCC₆H₁₁COOH
Out of these, the only formula that suggests a corresponding amount of hydrogen ions available for neutralization and fits the combustion data is C) HOOCCCOOH, as it can produce 0.0200 mol of CO₂.