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What forms a rock?
Many things can form a rock. Solidification of magma, compaction of sediment, and recrystalisation (metamorphosis) resulting from heat and pressure are main ones. Rock cycle here: http://www.teachnet-lab.org/ps101/bglasgold/rocksEFCycleP2.gif
What is the process of purification?
It simply means, isolating a chemical so there are no other compounds present with in the mixture other than just the one you want. E.g. C6H5COONa(aq) + HCl(aq) --> C6H5COOH(s) + NaCl(aq). To make pure benzoic acid you would neeed to use the purification process known as recrystalisation. The precipitate formed in this reaction would not be pure, it would contain some unreacted sodium benzoate and some undissolved sodium chloride along with any other original impurities.. Benzenoic acid is not soluble in cold water but is completely soluble in hot water (95`C). First dissolve benzoic acid completely in hot water, then cool and allow the ppt to form, this should be almost pure benzoic acid, the more times you recrystalise the more pure the sample, however % yield does decrease.
What does Tollens reagent Fehlings solution 2 4-Dinitrophenylhydrazine and Benedicts solution test for and what are the results?
Brady's reagent (2,4-DNP) forms a orange precipitate for all carbonyl compounds (C=O functional group), both aldehydes (primary) and ketones (secondary). However, recrystalisation of the orange precipitate gives characteristic melting points of the crystal for each carbonyl compound (therefore the presence of an orange precipitate indicates a carbonyl compound and the melting point of the crystallised precipitate indicates the type of carbonyl compound; aldehyde or ketone). Tollen's reagent (diamminesilver nitrate solution) is reduced and forms a silver mirror when heated with an aldehyde. It distinguishes between aldehydes and ketones as ketones do not react (no silver mirror formed) as they can not be oxidised further. Fehling's solution (copper II ions in sodium hydroxide) is reduced from a blue solution (Cu II ions) to a brick red precipitate (Cu I ions) when heated in the presence of an aldehyde. Ketones do not react as they can not be oxidised further. The Benedict's test is used in organic chemistry to distinguish between reducing sugars (brick red precipitate formed) and non-reducing sugars (no reaction).
What does purification mean?
Though the ritual may vary from religions the idea of purification is to remove some form of spiritual evil or taboo..Catholic AnswerIn the Catholic religion, purification has a very specific meaning, it means that you are removing any trace of the Precious Body and Blood of Our Blessed Lord from the Paten and Chalice after they have been used at Mass. They are ritually purified by rinsing with water (which is consumed by the priest) and then dried with a linen towel called a purificator.
Why do certain food go bad?
Staling, or "going stale" is a chemical and physical process in bread and other foods that reduces their palatability. Stale bread is dry and leathery.Staling is not, as is commonly believed, simply a drying-out process due to evaporation. Bread will stale even in a moist environment, and stales most rapidly at temperatures just above freezing. (McGee 2004, p. 310) Bread stored in the refrigerator will have increased staling rates and should therefore be kept at room temperature.Although the precise mechanism of staling is still unknown, one important mechanism appears to be migration of moisture from the starch granules into the interstitial spaces, degelatinizing the starch. The starch amylose and amylopectine molecules realign themselves causing recrystalisation. This results in stale bread's leathery, hard texture.Additionally, pleasant "fresh" flavor is lost to the air, and often unpleasant flavor is absorbed from it as well, especially in a confined space with other food such as a refrigerator.Anti-staling agents used in bread are fatty acids as monoglyceride and diglyceride and wheat gluten.
