Practically everyone in school or student's days faced the solution of tasks in chemistry, and some continue to be engaged in them to this day, working in the field or just helping the child on study. Types of chemical tasks are tasks with equivalents, calculating which you can meet some difficulties.
Instruction
1. It is known that an equivalent of substance or just an equivalent it is accepted to call a particle (real or imaginary) which has to be equivalent to an electron or a cation of hydrogen in oxidation-reduction or ion-exchange reactions, respectively, by connection with one of atoms of hydrogen, its replacement or release. So, for example, in chemical reaction of HCl + NaOH = NaCl + H2O an equivalent will be a real particle — Na+ ion, and in reaction 2HCl + Zn(OH)2 = ZnCl2 + 2H2O – a conditional particle of Zn (OH) 2.
2. Besides, now quite often mean equivalent amount of substance or quantity of equivalents of substance by the term "substance equivalent". Understand such number of mol of any given substance which in the considered reaction is equivalent to one mol of cations of hydrogen as all this.
3. To calculate value of an equivalent in reaction, it is possible and without resorting to its connections with hydrogen atoms. It means that the equivalent of substance can be defined, knowing structure of compound of substance with other chemical element at which the value of an equivalent is already in advance known.
4. Equivalents of complex substances can be learned, proceeding from the law of equivalence which was opened by the German chemist I.V. Richter in 1792. This law says that all substances entering with each other chemical reaction react in the equivalent relations. This formulation can be expressed a formula of the following look: m1E2=m2E1.
5. Thus, equivalents of complex substances, according to the law of equivalents and the above-stated formula, will be calculated so: Oxide equivalent = (Molar Mass of Oxide) / (Valency Elementa*Chislo Atomov of the Element); Acid Equivalent = (Molar Mass of Acid) / (Basicity of Acid); Basis Equivalent = (Molar Mass of the Basis) / (Acidity of the Basis).