!Answer!:  69.95% Na_{2}Co_{3}; 30.02% NaHCO_{3}.

26.  In the analysis of a one-gram sample of soda ash, what must be the normality of the acid in order that the number of cubic centimeters of acid used shall represent the percentage of carbon dioxide present?

!Answer!:  0.4544 gram.

27.  What weight of pearl ash must be taken for analysis in order that the number of cubic centimeters of 0.5 N acid used may be equal to one third the percentage of K_{2}Co_{3}?

!Answer!:  1.152 grams.

28.  What weight of cream of tartar must have been taken for analysis in order to have obtained 97.60% KHC_{4}H_{4}O_{6} in an analysis involving the following data:  NaOH used = 30.06 cc.; H_{2}so_{4} solution used = 0.50 cc.; 1 cc.  H_{2}so_{4} sol. = 0.0255 gram CaCO_{3}; 1 cc.  H_{2}so_{4} sol. = 1.02 cc.  NaOH sol.?

!Answer!:  2.846 grams.

29.  Calculate the percentage of potassium oxide in an impure sample of potassium carbonate from the following data:  Weight of sample = 1.00 gram; HCl sol. used = 55.90 cc.; NaOH sol. used = 0.42 cc.; 1 cc.  NaOH sol. = 0.008473 gram of KHC_{2}O_{4}.H_{2}C_{2}O_{4}.2H_{2}O; 2 cc.  HCl sol. = 5 cc.  NaOH sol.

!Answer!:  65.68%.

30.  Calculate the percentage purity of a sample of calcite (CaCO_{3}) from the following data:  (Standardization); Weight of H_{2}C_{2}O_{4}.2H_{2}O = 0.2460 gram; NaOH solution used = 41.03 cc.; HCl solution used = 0.63; 1 cc.  NaOH solution = 1.190 cc.  HCl solution. (Analysis); Weight of sample 0.1200 gram; HCl used = 36.38 cc.; NaOH used = 6.20 cc.

!Answer!:  97.97%.

31.  It is desired to dilute a solution of hydrochloric acid to exactly 0.05 N. The following data are given:  44.97 cc. of the hydrochloric acid are equivalent to 43.76 cc. of the NaOH solution.  The NaOH is standardized against a pure potassium tetroxalate (KHC_{2}O_{4}.H_{2}C_{2}O_{4}.2H_{2}O) weighing 0.2162 gram and requires 49.14 cc.  How many cc. of water must be added to 1000 cc. of the aqueous hydrochloric acid?

!Answer!:  11 cc.

32.  How many cubic centimeters of 3 N phosphoric acid must be added to 300 cc. of 0.4 N phosphoric acid in order that the resulting solution may be 0.6 N?

!Answer!:  25 cc.

33.  To oxidize the iron in 1 gram of FeSO_{4}(NH_{4})_{2}so_{4}.6H_{2}O (mol. wgt. 392) requires 3 cc. of a given solution of HNO_{3}.  What is the normality of the nitric acid when used as an acid? 6FeSO_{4} + 2HNO_{3} + 2H_{2}so_{4} = 3Fe_{2}(so_{4})_{3} + 2no + 4H_{2}O.

!Answer!:  0.2835 N.

34.  The same volume of carbon dioxide at the same temperature and the same pressure is liberated from a 1 gram sample of dolomite, by adding an excess of hydrochloric acid, as can be liberated by the addition of 35 cc. of 0.5 N hydrochloric acid to an excess of any pure or impure carbonate.  Calculate the percentage of Co_{2} in the dolomite.