Determine the number of equivalents and milliequivalents in...

Determine the number of equivalents and milliequivalents in 5.00 g of each of the following salts. Include any waters of hydration given in the salt formula when you calculate salt formula weights. a. $\mathrm{Na}_2 \mathrm{CO}_3 \cdot 10 \mathrm{H}_2 \mathrm{O}$ b. $\mathrm{CuSO}_4 \cdot 5 \mathrm{H}_2 \mathrm{O}$ c. $\mathrm{Li}_2 \mathrm{CO}_3$ d. $\mathrm{NaH}_2 \mathrm{PO}_4$

Determine the number of equivalents and milliequivalents in 5.00 g of each of the following salts. Include any waters of hydration given in the salt formula when you calculate salt formula weights.
a. $\mathrm{Na}_2 \mathrm{CO}_3 \cdot 10 \mathrm{H}_2 \mathrm{O}$
b. $\mathrm{CuSO}_4 \cdot 5 \mathrm{H}_2 \mathrm{O}$
c. $\mathrm{Li}_2 \mathrm{CO}_3$
d. $\mathrm{NaH}_2 \mathrm{PO}_4$

Key Concepts

Equivalent Weight

Equivalent weight is a concept in stoichiometry that represents the amount of a substance that will react with or supply one mole of reactive species (such as hydrogen ions, hydroxide ions, or electrons) in a chemical reaction. It is calculated by dividing the molecular or formula weight by the number of functional reactive units (or valence) present in the molecule. This concept allows for comparison and conversion between different substances based on their chemical reactivity rather than their molar mass.

Milliequivalents

A milliequivalent is one-thousandth of an equivalent. This unit is particularly useful when dealing with dilute solutions or when smaller quantities of reactive units are involved. It is commonly used in fields like clinical chemistry and water treatment, allowing precise measurement of substance reactivity in milligram-level amounts.

Molar Mass Calculation Including Waters of Hydration

Molar mass calculation in salts, especially those that include waters of hydration, requires that all components of the compound, including the water molecules coordinated in the crystal structure, be accounted for in the total formula weight. These water molecules add to the overall mass of the compound and must be included in any stoichiometric calculations involving moles and equivalents.

Conversion from Mass to Moles and Equivalents

To determine the number of equivalents or milliequivalents from a given mass of a substance, one must first convert the mass to moles using the compound’s full molar mass. Then, using the equivalent factor—which represents the number of reactive units per mole—one can calculate the number of equivalents. Multiplying by 1000 gives the result in milliequivalents. This process is fundamental in analytical chemistry for quantitative analysis of substances.

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