In a Kjeldahl analysis, ammonia from 1.000 g of a food sample is absorbed in 40.0 mL of 0.1000 M H2SO4. The excess acid (both protons) needs 22.1 mL of 0.2000 M NaOH. Taking N = 14, find the mass percent of nitrogen (two decimals).

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In a Kjeldahl analysis, ammonia from $1.000 g$ of a food sample is absorbed in $40.0 mL$ of $0.1000 M$ $H X_{2} SO X_{4}$ . The excess acid (both protons) needs $22.1 mL$ of $0.2000 M$ $NaOH$ . Taking N = 14, find the mass percent of nitrogen (two decimals).

Numerical answer type, answer in %, tolerance 0.02.

Answer: 5.01 %

H+ supplied = 2 x 0.0400 x 0.1000 = 0.0080 mol. NaOH used = 0.0221 x 0.2000 = 0.00442 mol = H+ left over. H+ neutralised by NH3 = 0.00358 mol = mol N. Mass N = 0.00358 x 14 = 0.0501 g; percent = 5.012, about 5.01%.

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In a Kjeldahl analysis, ammonia from 1.000 g of a food sample is absorbed in 40.0 mL of 0.1000 M HX2​SOX4​. The excess acid (both protons) needs 22.1 mL of 0.2000 M NaOH. Taking N = 14, find the mass percent of nitrogen (two decimals).

Answer: 5.01 %

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In a Kjeldahl analysis, ammonia from $1.000 g$ of a food sample is absorbed in $40.0 mL$ of $0.1000 M$ $H X_{2} SO X_{4}$ . The excess acid (both protons) needs $22.1 mL$ of $0.2000 M$ $NaOH$ . Taking N = 14, find the mass percent of nitrogen (two decimals).