Question: 5. Explain the meaning of the following terms: (a) chromophore (c) spiking (b) auxochrome 6. Nitrite in water can be determined by its reaction with sulphanilimide and N-(1-naphthyl)ethylenediamine to give a pink-coloured complex. Five standard solutions of nitrite were prepared, the pink colour was developed and the absorbances were recorded at 550 nm as

5. Explain the meaning of the following terms: (a) chromophore (c) spiking (b) auxochrome 6. Nitrite in water can be determined by its reaction with sulphanilimide and N-(1-naphthyl)ethylenediamine to give a pink-coloured complex. Five standard solutions of nitrite were prepared, the pink colour was developed and the absorbances were recorded at $550\mathrm{nm}$ as shown in the table below. (a) Plot a calibration curve from the data given. (b) Determine by interpolation of the calibration curve, the nitrite concentration of an unknown sample which gave an absorbance of $0.035$. (c) Using Beer-Lambert law, calculate the molarabsorptivity (ع) assuming that the cell path is $1\mathrm{cm}$. 7. Explain how UV-VIS spectroscopy can be used to distinguish between ${\mathrm{CH}}_3\mathrm{CH}(\mathrm{OH})\mathrm{CHO}$ and ${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{COOH}$.