In Kjeldahl's estimation of nitrogen, the standard formula used to calculate the percentage of nitro — Qualitative and Quantitative Analysis Chemistry Question
Question
In Kjeldahl's estimation of nitrogen, the standard formula used to calculate the percentage of nitrogen is $\%N = \frac{1.4 \times (N_1V_1 - N_2V_2)}{W}$. Physically, what does the term $(N_1V_1 - N_2V_2)$ directly represent?
Answer: C
💡 Solution & Explanation
$N_1V_1$ represents the total milli-equivalents of standard acid taken. $N_2V_2$ represents the milli-equivalents of base used in back-titration, which equals the unreacted acid. The difference $(N_1V_1 - N_2V_2)$ gives the milli-equivalents of acid neutralized by the evolved $NH_3$. Thus, it exactly equals the milli-equivalents of $NH_3$ produced.
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