An oxide of metal contains 40% oxygen by weight. What is the equivalent weight of metals?

To find the equivalent weight of the metal in the oxide, we can use the information given about the percentage of oxygen. Let's break it down step by step.

Understanding the Composition

The oxide contains 40% oxygen by weight. This means that in 100 grams of the oxide, there are 40 grams of oxygen and 60 grams of the metal.

Calculating Molar Mass of Oxygen

The molar mass of oxygen (O) is approximately 16 g/mol. Therefore, in 40 grams of oxygen, we have:

• Number of moles of oxygen = 40 g / 16 g/mol = 2.5 moles

Finding the Molar Mass of the Metal

Let the molar mass of the metal be represented as M. The formula for the metal oxide can be assumed to be MO, where M is the metal and O is oxygen. Since there are 2.5 moles of oxygen, there must also be 2.5 moles of the metal. Thus, the weight of the metal in the oxide is:

• Weight of metal = 60 g

Calculating Equivalent Weight

Using the number of moles of the metal, we can find its molar mass:

• M = 60 g / 2.5 moles = 24 g/mol

The equivalent weight of the metal is calculated by dividing the molar mass by the valency. Assuming the metal has a valency of 2 (as in many metal oxides), the equivalent weight would be:

• Equivalent weight = M / Valency = 24 g/mol / 2 = 12 g/equiv

In summary, the equivalent weight of the metal in the oxide is 12 grams per equivalent.