What is a compound

gently heat the mixture of iron filings and sulfur powder in a test tube. After sometime, a coloured substance is left behind. Bring a magnet near it. 

Cut the substance into smaller pieces and test them with the same magnet. The magnet has no effect. Iron loses its property in the new substance. This is a compound called iron sulfide containing iron and sulfur. The same elements, iron and sulfur, can form both mixtures and compounds. Can you think of other elements which forms both mixtures and compounds Compounds contain two or more elements. The elements chemically combine together to form a compound with different properties. 

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What is a compound What are compoimds composed of What is true about the composition of a compound, no matter where we happen to hnd the compound ... 

What is an element and what is a compound Give examples of each. What does it mean to say that a com-poimd has a constant composition Would samples of a particular compoimd here and in another part of the world have the same composition and properties ... 

Cold, and similarly for Moist and Dry. The elements were characterised by the pairs of compatible extremes which they displayed in isolation (water is Cold and Moist, earth is Cold and Dry, etc.) but lost when brought together in a mixing process which therefore destroys the elements and creates a compound in their place. Loss of these features means, on the Aristotelian view, that there are no elements in compounds because no part of what is a compound bears the defining characteristics of any of the elements. Elements only occur in isolation. 

What is a compound What is meant by the law of constant composition for compounds and why is this law so important to our study of chemistry ... 

A compound is a cyclic ether of molecular formula C9H10O Its NMR spectrum is shown in Figure 16 10 Oxidation of the compound with sodium dichromate and sulfunc acid gave 1 2 benzenedicarboxylic acid What is the compound d... 

Hydrolysis of a compound A in dilute aqueous hydrochlonc acid gave (along with methanol) a compound B mp 164—165°C Compound B had the molecular formula CigHig04 it exhibited hydroxyl absorption in its IR spectrum at 3550 cm but had no peaks in the carbonyl region What IS a reasonable structure for compound B" ... 

Commercial mesityl oxide (CH3)2C=CHCCH3 is often contam mated with about 10% of an isomer having the same carbon skeleton What is a Jikely structure for this compound ... 

When levuhnic acid (CH3CCH2CH2CO2H) was hydrogenated at high pressure over a nickel catalyst at 220°C a single product C5Hg02 was isolated in 94% yield This compound lacks hydroxyl absorption in its IR spectrum and does not immediately liberate carbon dioxide on being shaken with sodium bicarbonate What is a reasonable structure for the compound" ... 

Treatment of 2 4 6 tn tert butylphenol with bromine in cold acetic acid gives the compound CigH29BrO in quantitative yield The infrared spectrum of this compound contains absorptions at 1630 and 1655 cm Its H NMR spectrum shows only three peaks (all singlets) at 8 1 2 13 and 6 9 in the ratio 9 18 2 What is a reasonable structure for the compound" ... 

BICINE is a compound containing a tertiary amino group whose relevant pAT is 8.3 (Figure 2.18). Given 1 L of 0.05 M BICINE with its tertiary amino group in the uiiprotoiiated form, how much O.l N HCl must be added to have a BICINE buffer solution of pH 7.5 What is the molarity of BICINE in the final buffer ... 

A anmileue is a compound with three adjacent double bonds. Draw an orbital picture of a cumulene. What kind of hybridization do the two central carbon atoms have What is the geometric relationship of the substituents on one end to the substituents on the other end What kind of isomerism is possible Make a model to help see the answer. 

The lH NMR spectrum shown is that of a compound with formula C9H ]0O. How many double bonds and/or rings does this compound contain If the unknown has an 1R absorption at 1690 cm"1, what is a likely structure ... 

What is a reconstructed ion chromatogram (RiC) and how does it aiiow a specific compound to be iocated in the totai-ion current (TiC) trace from an LC-MS anaiysis ... 

The smaller the p/fa, the more acidic the proton is. This probably seems strange, but that s the way it is. A compound with a p/fa of 4 is more acidic than a compound with a p/fa of 7. Next, we need to know what the difference is between 4 and 7. These numbers measure orders of magnitude. So the compound with a pZa of 4 is 10 times more acidic (1000 times more acidic) than a compound with... 

Ans. You can tell from the context. For example, if a problem asks if a sample is a solution or a mixture, the word mixture means heterogeneous mixture. If it asks whether the sample is a compound or a mixture, it means any kind of mixture. Such usage occurs in ordinary English as well as in technical usage. For example, the word day has two meanings—one a subdivision of the other. How many hours are there in a day What is the opposite of night "... 

Two questions should immediately arise, (a) How can you know exactly when to stop the titration so that the number of moles of NaOH is equal to the number of moles of HCI (b) What is the use of determining the concentration of a solution of NaOH when the NaOH has now been used up reacting with the HCI (a) An indicator is used to tell us when to stop the titration. Typically an indicator is a compound that is one color (or colorless) in an acidic solution and a second color in a basic solution. Thus, we add NaOH slowly, drop by drop toward the end, until a permanent color change takes place. At that point, the end point has been reached, and the titration is complete. The HCI has just been used up. (b) The purpose of doing a titration is to determine the concentration of a solution. If the concentration of a liter of NaOH is to be determined, a small portion of it is used in the titration. The rest has the same concentration, and although the part used in the titration is no longer useful, the concentration of the bulk of the solution is now known. 

Ethyl acetate is reduced by hydrogen in the presence of a catalyst to yield one organic compound, which contains oxygen but is not an ether. What is the compound ... 

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