Equivalent weight facts for kids
In chemistry, the equivalent weight of a substance is also called its gram equivalent. It tells us how much of a substance will react with or replace a certain amount of another substance. Think of it like a specific amount that always does the same job in a chemical reaction.
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What is Equivalent Weight?
The equivalent weight helps chemists understand how different chemicals combine. It's the amount of a substance that will react with a fixed amount of another. This idea is important for balancing chemical reactions.
How It Works for Elements
For a chemical element, its equivalent weight is the mass that combines with or replaces specific amounts of other common elements. These amounts are:
These numbers come from the element's atomic weight divided by its valence. Valence is like an element's "combining power." For example, oxygen has an atomic weight of about 16.0 grams and a valence of 2. So, its equivalent weight is 16.0g / 2 = 8.0 grams.
Equivalent Weight for Compounds
The equivalent weight of a compound is found differently. You take the compound's molecular weight and divide it by the total number of positive or negative electrical charges its ions carry. Ions are atoms or molecules that have gained or lost electrons, giving them an electrical charge. This usually happens when the compound dissolves in a liquid.
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Jeremias Benjamin Richter (1762–1807) was one of the first chemists to write down tables of equivalent weights. He also created the word "stoichiometry", which is the study of how much of each substance is involved in chemical reactions.
