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Bromothymol blue (also known as bromothymol sulfone phthalein and BTB) is a pH indicator. It is mostly used in applications that require measuring substances that would have a relatively neutral pH (near 7). A common use is for measuring the presence of carbonic acid in a liquid. It is typically sold in solid form as the sodium salt of the acid ...
From numbers of equivalent portions of acid bromine formed from the previous reaction, the ratio between oxygen and bromine was calculated, with the exact value of O:Br (0.149975:0.3745), suggesting the acid compound contains two oxygen atom to one bromine atom. Thus, the chemical structure of the acid compound was deducted as HBrO 2. [2]
View of salt evaporation pans on the Dead Sea, where Jordan (right) and Israel (left) produce salt and bromine. Bromine is significantly less abundant in the crust than fluorine or chlorine, comprising only 2.5 parts per million of the Earth's crustal rocks, and then only as bromide salts. It is the 46th most abundant element in Earth's crust.
Bond energies to bromine tend to be lower than those to chlorine but higher than those to iodine, and bromine is a weaker oxidising agent than chlorine but a stronger one than iodine. This can be seen from the standard electrode potentials of the X 2 /X − couples (F, +2.866 V; Cl, +1.395 V; Br, +1.087 V; I, +0.615 V; At, approximately +0.3 V).
For determining the acid value of mineral oils and biodiesel, there are standard methods such as ASTM D 974 and DIN 51558, and especially for biodiesel the European Standard EN 14104 and ASTM D664 are both widely used worldwide. [2] Acid value of biodiesel should be lower than 0.50 mg KOH/g in both EN 14214 and ASTM D6751 standard fuels.
When an acid is dissolved in water, the pH will be less than 7, while a base, or alkali, will have a pH greater than 7. A strong acid, such as hydrochloric acid, at concentration 1 mol dm −3 has a pH of 0, while a strong alkali like sodium hydroxide, at the same concentration, has a pH of 14. Since pH is a logarithmic scale, a difference of ...
The Frost diagram is also a useful tool for comparing the trends of standard potentials (slope) of acidic and basic solutions. The pure, neutral element transitions to different compounds depending whether the species is in acidic and basic pHs. Though the value and amount of oxidation states remain unchanged, the free energies can vary greatly.
In this case H 0 and H − are equivalent to pH values determined by the buffer equation or Henderson-Hasselbalch equation. However, an H 0 value of −21 (a 25% solution of SbF 5 in HSO 3 F ) [ 5 ] does not imply a hydrogen ion concentration of 10 21 mol/dm 3 : such a "solution" would have a density more than a hundred times greater than a ...