Classifying Electrolytes

Electrolytes are substances which, when dissolved in water, break up intocations (plus-charged ions) & anions (minus-charged ions). We say they ionize.

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Strong electrolytes ionize completely (100%), while weak electrolytesionize only partially (usually on the order of 1–10%). That is, the principal speciesin solution for strong electrolytes are ions, while the principal specie in solution for weak electrolytes is the un-ionized compound itself.Strong electrolytes fall into three categories: strong acids,strong bases, & salts. (Salts are sometimes also called ionic compounds, but really strongbases are ionic compounds as well.) The weak electrolytes include weak acids and weak bases.Examples of strong and weak electrolytes are given below:
Strong Electrolytes strong acidsHCl, HBr, HI, HNO3, HClO3, HClO4, and H2SO4 strong basesNaOH, KOH, LiOH, Ba(OH)2, và Ca(OH)2 saltsNaCl, KBr, MgCl2, and many, many moreWeak Electrolytes weak acidsHF, HC2H3O2 (acetic acid), H2CO3 (carbonic acid), H3PO4 (phosphoric acid), and many more weak basesNH3 (ammonia), C5H5N (pyridine), and several more, all containing "N"

Being Able to Classify Electrolytes Is Critical

As chemists, we need to be able to look at a formula such as HCl or NaOH và quickly knowwhich of these classifications it is in, because we need to lớn be able toknow what we are working with (ions or compounds) when we are working withchemicals. We need to know, for example, that a bottle labeled "NaCN" (a salt) really containsno NaCN, rather Na+ & CN–, or that a bottle labeled "HCN" (a weak acid) is principally HCNwith a small amount of H+ và CN– also present. The difference between just opening a bottle labeled "HCN" & one labeled "NaCN" could be your life, as HCN, or hydrogen cyanide, is a toxic gas, while CN–, or cyanide ion, being an ion, isn"t a gas & is only transfered in solid or solution form. Nonetheless, it is cyanide ion, CN–, that is the killer. (It locks onto the Fe3+ in hemoglobin, causing less oxygen khổng lồ get to lớn your brain.) Cyanide is present in both bottles, & if it is transfered to lớn your bloodstream either as CN– or as HCN, it will kill you.

Six Steps for Categorizing Electrolytes

So how vị we categorize compounds based on their formula? One practical method is outlined below:
Step 1Is it one of the seven strong acids?Step 2Is it of the khung Metal(OH)n? Then it"s a strong base.Step 3Is it of the khung Metal(X)n? Then it"s a salt.Step 4Does it"s formula start with "H"? It"s probably a weak acid.Step 5Does it have a nitrogen atom? It may be a weak base.

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Step 6None of those? gọi it a nonelectrolyte.
Note that there are ambiguities here starting in Step 4. That"s just the way it is. Khổng lồ determine whether a substance is a weak acid or weak base you have khổng lồ know more than the molecular formula, especially for compounds containing carbon. (A structural formula, which shows the detailed connections of atoms is often necessary.)SummaryIn summary, know the more common element names and symbols, memorize the seven strong acids, be able to spot a metal (know at least where they are on theperiodic table), memorize at least a few of the more common weak acids & weak base,and you will be in good shape. YOU CAN bởi IT!