Sulphuric acid related examples

The other more electronegative elements are non-metals and form oxides which are entirely covalent and usually acidic. For example, sulphur yields the oxides SO2 and SO3, dissolving in bases to form the ions SO3 and SO4" respectively. A few non-metallic oxides are often described as neutral (for example carbon monoxide and dinitrogen oxide) because no directly related acid anion is known to exist. 

Apart from the three broad categories of student conceptions discussed above, students displayed several inappropriate conceptions relating to the stractural properties of substances. For example, 14% of students suggested that Mg + ions were present in magnesium ribbon. A second example involved the chemical reaction between copper(II) oxide powder and dilute sulphuric acid. In this instance, 25% of students suggested that Cu + ions were present only in aqueous solution but not in the solid and liquid states. This view was rather unexpected because students had earlier been introdnced to ionic and covalent compounds. It is likely that students had merely rote-learned the general rale without sufficient understanding that ionic solids are formed between metallic and non-metallic elements. 

Examples of secondary metabolites from Ascidians are shown in Figure 3.10. Ascidians are noteworthy for the presence of vanadium (and related metals) together with high concentrations of sulphuric acid and tunichromes, which are unstable hydroquinoid compounds. A defensive role for these has been suspected,98 and it is noteworthy that gastropod molluscs (both prosobranch and opisthobranch) that feed upon tunicates often secrete large amounts of sulfuric acid, used in both... 

The results demonstrate that hydrogensulfate and tetrakis(hydrogensulfato)borate ionic liquids are highly interesting additives to mineral acids to form new, highly Bronsted-acidic catalysts. For example, it was found that a mixtures of sulphuric acid with only 2.2 mol% of [0MIM][B(HS04)4] ionic liquid yielded 90% more monoalkylbenzene product than the neat sulphuric acid catalyst under identical reaction conditions. This and related results are explained by an interplay of solubility and acidity effects caused by the ionic liquid additive. 

In relation to acids, therefore, water acts the part of a base in relation to bases, that of an acid and in relation to neutral salts, that of a neutral or indifferent substance, or, indeed, of a neutral salt. Taking the three examples of hydrated sulphuric acid, HO, SO, hydrate of potash, KO, HO, and dry sulphate of iron, FeO, SO,HO, it is to be observed that the water in the first can only be replaced by a base, such as potash, KO, w hich would yield sulphate of potash, KO, SO, the water in the second can only be replaced by an acid, such as sidphnric acid, SO, which would yield the same salt,KO,SO, and the water in the third rrray be replaced by a neutr salt, such as sulphate of potash, K 0, S 0, which would give rise to the double salt, FeO, SO, -HKO, SO,. Water in these three different characters is called basic water, hydratic water, and saline water, and, in addition to these, we have water of crystallisation. 

For an earlier example, see the relation between Gay-Lussac and John Glover concerning production of sulphuric acid. Cf W.A. Campbell, Industrial chemistry, in C.A. Russell, ed.. Recent Developments in the History of Chemistry (London Royal Society of Chemistry, 1985), p. 243. 

The amount to be applied to the layer in stability testing is governed in particular by the sensitivity of the method of detection and the related question, beyond what degree of decomposition the activity of the preparation becomes really impaired or the decomposition products show an undesireable side effect. An example may be seen in Fig. 168. The resolved steroid mixture can be detected with either dinitrophenyl-hydrazine (Rgt. No. 82) or sulphuric acid (Rgt. No. 241B), followed by inspection in UV light. In this particular case, the sulphuric acid reaction is too sensitive, since it detects impurities and degradation products which are without therapeutic interest [64]. 

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