Question

Suppose you need to prepare 138.0 mL of a 0.449 M aqueous solution of NaCl.

What mass of NaCl do you need to use to make the solution?

Answer 1

To prepare 138.0 mL of a 0.449 M NaCl solution, 3.62 grams of NaCl are needed. This is calculated by multiplying the molarity by the volume in liters to get moles, and then converting moles to grams using the molar mass of NaCl.

Step-by-step explanation:

To calculate the mass of NaCl needed to prepare 138.0 mL of a 0.449 M NaCl solution, follow these steps:

1. Calculate the number of moles of NaCl using the formula: moles = molarity × volume in liters. For a 0.449 M solution, we have: moles = 0.449 M × 0.138 L (138.0 mL converted to liters) = 0.061962 mol.
2. Convert the moles of NaCl to grams using the molar mass of NaCl (58.44 g/mol). Mass = moles × molar mass = 0.061962 mol × 58.44 g/mol = 3.62 g.

You would need to weigh out 3.62 grams of NaCl and dissolve it in water to prepare your solution.