Problem: Brass is a substitutional alloy consisting of a solution of copper and zinc. A particular sample of red brass consisting of 81.0% Cu and 19.0% Zn by mass has a density of 8760 kg/m3 .What is the molality of Zn in the solid solution?

FREE Expert Solution

We’re being asked to calculate for the molality of Zn within a particular sample of red brass consisting of 81.0% Cu and 19.0% Zn by mass that has a density of 8760 kg/m3.


When calculating for molality, we use the following equation:

Solid solution → Cu is the solvent

Solute → Zn


We will calculate the molality of the solution using the following steps:

Step 1. Calculate the mass of the solvent (in kg).

Step 2. Calculate the moles of Zinc.

Step 3. Calculate the molality of the solution.



Since we are calculating for the molality, recall the formula:

molality (m) = mol solutekg solvent


Assume that we have 1000g of Brass solution.

Step 1. Calculate the mass of the Cu and Zn (in g).

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Problem Details

Brass is a substitutional alloy consisting of a solution of copper and zinc. A particular sample of red brass consisting of 81.0% Cu and 19.0% Zn by mass has a density of 8760 kg/m3 .

What is the molality of Zn in the solid solution?

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What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Molality concept. You can view video lessons to learn Molality. Or if you need more Molality practice, you can also practice Molality practice problems.

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