9.25. In standardizing a soln. of NaOH against 1.431 g of potassium acid phthalate, the analyst uses 35.50 mL of the alkali and has to run back with 5.12mL of acid (1.000mL=0.003100 g Na2O). What is the normality of the NaOH soln.?
9.28. A sample of crude ammonium salt weighing 1.000g is treated with hot KOH soln. The NH3 liberated is collected in 50.00mL of 0.5000N acid, and the excess acid requires 3.12mL of 0.2500N NaOH for neutralization. Calculate the percentage of NH3 in the sample.
9.30. In order to have obtained 97.60% KHC4H4O6 what wt. of a sample of cream of tartar must have been taken for an analysis which involves the following data: NaOH used=30.06mL; H3SO4 used=0.50mL; 1.000mL H2SO4=0.02550 g CaCO3; 1.000mL H2SO4=1.020mL NaOH?