What mass of KH₂PO₄ should be measured out for the spectrophotometric method (1st lab period)?

0.17g		~0.1g
	~0.215		~0.44g
	0.56g

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What mass of fertilizer should be measured out for the second and third lab periods for the spectrophotometric method?

	~0.17g		~0.1g
	~0.215		~0.44g
	0.56g

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In the analysis of the fertilizer sample (2nd and 3rd lab period), what step should be included in the spectrophotometric analysis to remove insoluble material from the sample solution?

	No additional step is necessary.		The sample should be dissolved in water.
	The developing solution should be added first.		The sample solution should be filtered.
	The sample solution should be diluted.

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Why should a new calibration curve be generated for each lab period that the spectrophotometric analysis is performed?

	Because it is important to practice the technique.		Because we will use the slope from the calibration curve.
	Because the fertilizer sample may change slightly from one lab period to the next.		Because the spectrometer varies slightly from lab period to lab period.
	Because the heteropoly blue reagent may change slightly from one lab period to the next.

How is the presence of blue food dye in the fertilizer factored out when obtaining absorbance spectra of the colored fertilizer solutions during the second and third lab periods?

	By using the working fertilizer solution to make the blank solution (without the developing solution).		By using water as the blank solution.
	By using heteropoly blue solution to make the blank solution (without the working solution).		By removing the food dye.
	By changing the fertilizer to a different color.

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