When a small amount of 12 M HNO3(aq) is added to a buffer solution made by mixing CH3NH2(aq) and CH3NH3Cl(aq) , the pH of the buffer solution changes from 10.64 to 10.62. Which of the following equations represents the reaction that accounts for the fact that the pH does not change significantly when the HNO3(aq) is added? a. CH3NH2(aq) + H+(aq) â CH3NH3+(aq)

b. CH3NH3+(aq) + H+(aq) â CH3NH42+(aq)

c. NO3- (aq) + H+(aq) â HNO3(aq)

d. OH- (aq) + H+(aq) â H2O(l)

Harvey mixes two liquids. which observation of the new mixture most likely indicates a precipitate is forming?

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.

Describe the difference between a. a hypothesis and a theory and b. an observation and an experiment.