A solution is 0.0100 M in each of the metal ions in the following table: Metal sulfide Kspa
FeS 6×102
NiS 8×10−1
PbS 3×10−7
CuS 6×10−16
a) HCl is added to the solution so that the H3O+ concentration is 0.300 M. H2S gas is bubbled through the solution to attain a H2S concentration of 0.100 M. Predict which of the sulfides precipitate under the given conditions
Which will Precipitate and which will not?
b)The solution remaining from Part A, which contains 0.0100 M Ni2+ and Fe2+ ions, is still saturated with H2S gas, producing a concentration of 0.100 M. A buffer is added to this solution to produce a pH of 2.01 . Which of the following describes correctly the effect of the addition of the buffer?
a) Only NiS precipitates.
b) Only FeS precipitates.
c) Both NiS and FeS precipitate.
d) Neither NiS nor FeS precipitate.

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In a laboratory experiment, a fermenting aqueous solution of glucose and yeast produces carbon dioxide gas and ethanol. the solution was heated by burning natural gas in a bunsen burner to distill the ethanol that formed in the flask. during the distillation, the ethanol evaporated and then condensed in the receiving flask. the flame of the burner was kept too close to the bottom of the flask and some of the glucose decomposed into a black carbon deposit on the inside of the flask. during this experiment the following changes occurred. which of these changes involved a physical change and not a chemical change? check all that apply. 1-condensation of ethanol 2-evaporation of ethanol 3- formation of carbon dioxide gas from glucose burning of natural gas 4-formation of ethanol from glucose by yeast 5-formation of a carbon deposit inside the flask

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