In an electrolysis experiment, the ammeter records a steady current of 1A. The mass of copper deposited is 0.66g in 30 minutes. Calculate the error in the a...
Question 1 Report
In an electrolysis experiment, the ammeter records a steady current of 1A. The mass of copper deposited is 0.66g in 30 minutes. Calculate the error in the ammeter reading (Electrochemical equivalent of copper = 0.00033g C\(^{-1}\)).
Answer Details
Faraday's first law of electrolysis: \( m = zIt \), where \(z\) is the electrochemical equivalent.
Step 1: Convert the time. \( t = 30 \times 60 = 1800\,\text{s} \).
Step 2: Find the true (actual) current that must have flowed to deposit the copper.
\[ I = \frac{m}{zt} = \frac{0.66}{0.00033 \times 1800} = \frac{0.66}{0.594} = 1.11\,\text{A} \]Step 3: Compare with the ammeter reading. The ammeter shows \(1.0\,\text{A}\), but the mass of copper proves the true current was \(1.11\,\text{A}\).
\[ \text{Error} = 1.11 - 1.00 = 0.11\,\text{A} \]Answer: the ammeter under-reads by \(0.11\,\text{A}\). (As a percentage of the true value this is \(\tfrac{0.11}{1.11}\times100\% \approx 10\%\).)
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