Ammonia in seawater was measured with an ammonia-selective electrode. A 100.0 mL aliquot of seawater was treated with 1.00 mL of 10 M NaOH to convert NH⁺₄ to NH₃. Therefore,V₀ = 101.0 mL. A reading was then taken with the electrode. Then a series of 10.00 mL aliquots of standard NH⁺₄ Cl^- were added with results in the table.

The standard contains 100.0 ppm (mg/L) of nitrogen in the form of NH⁺₄Cl^-. A separate experiment determined that the electrode slope RT (ln 10)/F is 0.056 6 V.
(a) Prepare a standard addition graph. Find the concentration and 95% confidence interval for ammonia nitrogen (ppm) in the 100.0 mL of seawater.

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Vs (mL) E (V) -0.084 4 -0.058 1 -0.046 9 Vs (mL) E (V) 30.00 40.00 -0.039 4 -0.034 7 10.00 20.00