Answer is: because weak acids do not dissociate completely.
The strength of an Arrhenius
acid determines percentage of ionization of acid and the number of H⁺ ions formed. <span>
Strong acids completely ionize in water and give large amount ofhydrogen ions (H</span>⁺), so we use only one arrow, because reaction goes in one direction and there no molecules of acid in solution.
For example hydrochloric acid: HCl(aq) → H⁺(aq) + Cl⁻(aq).
<span>
Weak acid partially ionize in water
and give only a few hydrogen ions (H</span>⁺), in the solution there molecules of acid and ions.
For example cyanide acid: HCN(aq) ⇄ H⁺(aq)
+ CN⁻(aq).
Element M reacts with fluorine to form an ionic compound with the formula MF₄. The M cation has 18 electrons. Element M is Sn.
<h3>What is Ionic Compound ?</h3>
An ionic compound is defined as the compound made up of ions that formed charge particles when an atom loses or gains electrons.
<h3>What is Cation ?</h3>
Cations are positively charged ions. It forms when an element lose one or more electrons.
The cation which has 18 electrons is Sn. Sn react with fluorine to form an ionic compound with the formula SnF₄ because Sn is large and F is very small in size.
Thus from the above conclusion we can say that Element M reacts with fluorine to form an ionic compound with the formula MF₄. The M cation has 18 electrons. Element M is Sn.
Learn more about the Ionic Compound here: brainly.com/question/2687188
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Atomic mass of sodium is 22.9 g/mol
atomic mass of chloride is 35.45 g/mol
sodium chloride is 22.99 + 35.45= 58.44 g/mol