2.0 gram of alum is dissolve in 10 grams of water find the concentration of the soulution
Answers
Answer:
It had been a good year for the O’Keefe farm with just the right amount of sun
and rain. In fact, the cucumbers had grown so well that Richard was afraid he wouldn’t
be able to sell them fast enough. Faced with the prospect of a warehouse full of rotten
cukes, he contemplated the idea of preserving them and selling them as “O’Keefe’s Farm
Fresh Pickles”. He discussed the plan with his wife, Diane, who agreed it was a good
idea and said she had a delicious pickling recipe that had been handed down to her from
her mother.
“I recall one of the ingredients was alum. I think it helps to keep the pickles firm
and crisp,“ Diane said.
“It just so happens that I know of a recipe for making alum from aluminum cans,”
Richard said. “We can use some of those soda pop cans that have been piling up, and
that should save us some money.”
“How can you convert aluminum metal into an aluminum salt?” Diane asked.
Richard explained the chemistry behind the process:
One of the interesting properties of aluminum is that it is amphoteric, meaning it
will dissolve in both strong, aqueous acids and strong, aqueous bases (see Tro, pp 824-5).
In both cases, the formation of hydrogen gas is observed:
2 Al (s) + 6 H+ (aq) → 2 Al3+ (aq) + 3 H2 (g)
2 Al (s) + 6 H2O (l) + 2 OH– (aq) → 2 Al(OH)4
– (aq) + 3 H2 (g)
The first reaction that needs to be carried out is that of aluminum and potassium
hydroxide, KOH:
2 Al (s) + 2 KOH (aq) + 6 H2O (l) → 2 Al(OH)4
– (aq) + 2 K+ (aq) + 3 H2 (g)
Adding sulfuric acid, H2SO4, to the resulting solution will cause the compound Al(OH)3
to precipitate; however, Al(OH)3 is also amphoteric and will re-dissolve when more acid
is added:
2 K+ (aq) + 2 Al(OH)4
– (aq) + H2SO4 (aq) →
2 K+ (aq) + 2 Al(OH)3 (s) + 2 H2O(l) + SO4
2–
(aq)