A solution of HNO3 is standardized by reaction with pure sodium carbonate. 2 H+ + Na2CO3 → 2Na+ + H2O + CO2. A volume of 26.66 ± 0.06 mL of HNO3 solution was required for complete reaction with 0.8500 ± 0.0007 g of Na2CO3 , (FM 105.988 ± 0.001 g/mol). Find the molarity of the HNO3 solution and its absolute uncertainty.

V1t2 = v2t1 is an expression of who’s law

1. suppose a reaction mixture, when diluted with water, afforded 300 ml of an aqueous solution of 30 g of the reaction product malononitrile [ch2(cn)2], which is to be isolated by extraction with ether. the solubility of malononitrile in ether at room temperature is 20.0 g/100 ml, and in water is 13.3 g/100 ml. what weight of malononitrile would be recovered by extraction with (a) three 100-ml portions of ether and (b) one 300-ml portion of ether? suggestion: for each extraction, let x equal the weight extracted into the ether layer. in part (a), the concentration in the ether layer is x/100 and in the water layer is (30 x)/300; the ratio of these quantities is equal to k 20/13.3.

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.