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/m ^{3}_{.}*

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:

$\overline{){\mathbf{molality}}{\mathbf{}}{\mathbf{\left(}}{\mathbf{m}}{\mathbf{\right)}}{\mathbf{}}{\mathbf{=}}{\mathbf{}}\frac{\mathbf{mol}\mathbf{}\mathbf{solute}}{\mathbf{kg}\mathbf{}\mathbf{solvent}}}$

Assume that we have 1000g of Brass solution.

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

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/m^{3} .

What is the molality of Zn in the solid solution?

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