Preparing chemical solutions requires careful measurements to ensure accurate concentrations. In this article, we will explore how to calculate the mass of potassium bromide (KBr) needed to prepare 35.0 mL of a 1.80 M KBr solution. This calculation involves understanding the concepts of molarity, volume, and mass.
Molarity (M) is a measure of the concentration of a solution. It represents the number of moles of solute (KBr, in this case) dissolved in one liter of solution. Volume (V) refers to the amount of solution in milliliters (mL) or liters (L), while mass (m) represents the weight of the solute in grams (g) or kilograms (kg).
Calculating the Mass of KBr
Step 1: Convert Volume to Liters
First, convert the volume of the solution from milliliters (mL) to liters (L). Divide the volume by 1000 since 1 L equals 1000 mL.
35.0 mL / 1000 mL/L = 0.035 L
Step 2: Calculate the Number of Moles of KBr
Multiply the molarity of the solution (1.80 M) by the volume in liters to obtain the number of moles of KBr needed.
1.80 M x 0.035 L = 0.063 moles KBr
Step 3: Convert Moles to Grams
Finally, convert the number of moles of KBr to grams by multiplying by its molar mass. The molar mass of KBr is approximately 119.0 g/mol.
0.063 moles KBr x 119.0 g/mol = 7.497 g KBr
Additional Considerations
Purity of KBr
The purity of KBr used can affect the mass required. If the KBr is not 100% pure, you may need to adjust the mass accordingly.
Accuracy of Measurements
Ensure accurate measurements of volume and mass to obtain a precise result. Use calibrated equipment and measure carefully.
Importance of Calculations
Precise calculations are crucial to prepare accurate solutions for scientific experiments, chemical reactions, and other applications.
FAQ
What is the molarity of the KBr solution?
The molarity of the KBr solution is 1.80 M.
How many moles of KBr are needed?
0.063 moles of KBr are needed to prepare 35.0 mL of a 1.80 M KBr solution.
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What is the mass of KBr required?
The mass of KBr required is approximately 7.497 grams.
Does the purity of KBr affect the mass needed?
Yes, the purity of KBr can affect the mass needed. If the KBr is not 100% pure, the mass may need to be adjusted.
Why are accurate calculations important?
Accurate calculations are important to prepare accurate solutions for scientific experiments, chemical reactions, and other applications.
Conclusion
Calculating the mass of KBr needed to prepare 35.0 mL of a 1.80 M KBr solution involves converting volume to liters, calculating the number of moles of KBr, and converting moles to grams. Understanding these steps and considering factors such as KBr purity and accurate measurements is essential for precise solution preparation.