Question

Describe the basic steps involved in diluting a solution of known concentration.

Short answer

Determine desired concentration, calculate stock needed, measure it, and dilute to desired volume.

Step-by-step solution

Determine the Desired Concentration and Volume

First, decide what concentration and volume of the new diluted solution you want to prepare. This will be your target concentration (\( C_2 \)) and target volume (\( V_2 \)).

Calculate the Volume of Stock Solution Needed

Use the dilution formula \( C_1V_1 = C_2V_2 \), where \( C_1 \) is the initial concentration and \( V_1 \) is the volume of the stock solution needed. Rearrange the formula to solve for \( V_1 \): \( V_1 = \frac{C_2V_2}{C_1} \).

Measure the Stock Solution

Measure \( V_1 \), the volume of the stock solution you calculated in Step 2, using a graduated cylinder or pipette for accuracy.

Add Solvent to Reach the Desired Volume

Transfer \( V_1 \) of the stock solution into a new container. Add water or another appropriate solvent until the total volume reaches \( V_2 \). Mix the solution thoroughly to ensure uniform concentration.

Key concepts

Solution Concentration

The concept of solution concentration refers to how much solute is present in a given amount of solvent or solution. It can be expressed in several ways, but the most common units are molarity (M), which is moles of solute per liter of solution. Understanding concentration is crucial for tasks like dilutions, as it helps chemists know how much of a chemical is present.

• The solute is the substance dissolved in the solvent, forming the solution.
• The solvent is typically the component in greater quantity, like water in an aqueous solution.
• Concentration can change if more solute is added, or if the solvent evaporates/reduces.

For practical applications, particularly in chemical reactions or laboratory preparations, knowing the concentration ensures that reactions proceed as planned. This is essential for consistency and reliability in experimental results.

Dilution Formula

Diluting a solution involves lowering the concentration by adding more solvent. The key formula used to calculate dilutions is the dilution formula:\[ C_1V_1 = C_2V_2 \]where:

• \( C_1 \) is the initial concentration of the stock solution, often a concentrated solution.
• \( V_1 \) is the volume of the concentrated solution needed to achieve the desired dilution.
• \( C_2 \) is the target concentration of the diluted solution.
• \( V_2 \) is the final volume of the diluted solution, which includes the volume of the solvent added.

This equation helps in accurately calculating how much of the initial concentrated solution is necessary to achieve a desired concentration after dilution. It's important to ensure the units used for concentration and volume are consistent. Making a mistake can result in incorrect concentrations, impacting experimental outcomes.

Laboratory Techniques

In lab environments, diluting a solution is a fundamental skill that relies on precise methods to achieve accurate results. Several laboratory techniques are commonly used during dilution processes.

• A pipette or graduated cylinder is often used to measure specific volumes of liquids. This provides accuracy in measuring the stock solution.
• For final mixtures, using clean and appropriately sized glassware reduces contamination risk and enables a thorough mix.
• Mixing is crucial after dilution. Stirring or swirling ensures the concentration is uniform throughout the solution.

Good laboratory practices involve double-checking measurements, ensuring all equipment is calibrated, and keeping a clean working environment. These techniques minimize error and ensure the reliability of the dilution process, which is vital for any experimental or practical application.