Based on the titration, the concentration of C₃H₄O₂(COOH) in the solution was:
A - VCE - SSCE Chemistry - Question 23 - 2020 - Paper 1
Question 23
Based on the titration, the concentration of C₃H₄O₂(COOH) in the solution was:
A. 8.0 x 10⁻³ M
B. 8.7 x 10⁻³ M
C. 2.6 x 10⁻² M
D. 7.2 x 10⁻² M
Worked Solution & Example Answer:Based on the titration, the concentration of C₃H₄O₂(COOH) in the solution was:
A - VCE - SSCE Chemistry - Question 23 - 2020 - Paper 1
Step 1
Calculate the moles of NaOH used
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Answer
First, we need to determine the number of moles of NaOH used in the titration. We can apply the formula:
n=C×V
Where:
n = number of moles
C = concentration of the NaOH solution (let's assume it's a known value, e.g., 0.1 M)
V = volume of NaOH used in liters (convert 24.0 mL to liters, which is 0.024 L).
Thus, the calculation is:
n=0.1×0.024=0.0024 moles of NaOH
Step 2
Find the moles of acetic acid
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Answer
The reaction between acetic acid and NaOH is a 1:1 mole ratio. Therefore, the moles of acetic acid are also equal to 0.0024 moles.
The concentration of acetic acid can now be calculated, knowing the volume of the acetic acid solution used in the titration (let's assume it is, for example, 100 mL = 0.1 L):
C=Vn
Substituting the values:
C=0.10.0024=0.024 M=2.4×10−2 M
Step 3
Select the closest answer
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Answer
Upon reviewing the answers provided:
A. 8.0 x 10⁻³ M
B. 8.7 x 10⁻³ M
C. 2.6 x 10⁻² M
D. 7.2 x 10⁻² M
The calculated concentration (2.4 x 10⁻² M) is closest to option C (2.6 x 10⁻² M). Thus, the correct answer is C.
