Making a standard sulfate solution involves dissolving a precise amount of a sulfate-containing salt, like sodium sulfate, in a specific volume of water to achieve a known concentration of sulfate ions.
Based on the provided reference for a Sulfate Standard Solution, 1000μg/mL, Ion HIQU, Chem-Lab, here's how a standard solution with that specific concentration of sulfate ions (SO₄²⁻) is prepared:
Materials & Equipment
To prepare this specific standard sulfate solution, you would typically need:
- Sodium Sulfate (Na₂SO₄): A precise mass of high-purity anhydrous sodium sulfate.
- Water: A specific volume, usually ultrapure or distilled water, free from sulfate contamination.
- Volumetric Flask: A calibrated flask to ensure the final volume is precise.
- Analytical Balance: For accurately weighing the sodium sulfate.
- Glassware: Beaker for initial dissolution, stirring rod.
Preparation Method: 1000 μg/mL SO₄²⁻ Standard Solution
According to the reference, a 1000μg/mL SO₄²⁻ standard solution is prepared using sodium sulfate. The key steps involve accurate weighing and dissolution:
Step-by-Step Guide
Here is a general procedure based on the reference's description:
- Weigh the Salt: Accurately weigh 1.479 grams of sodium sulfate (Na₂SO₄) using an analytical balance.
- Dissolve the Salt: Transfer the weighed sodium sulfate to a clean beaker. Add a small amount of high-purity water (e.g., < 500 mL) and stir gently to ensure the salt completely dissolves.
- Transfer to Volumetric Flask: Carefully transfer the dissolved solution into a 1-liter volumetric flask. Rinse the beaker and stirring rod with small portions of water and add the rinsings to the volumetric flask to ensure all the dissolved salt is transferred.
- Dilute to Volume: Add high-purity water to the volumetric flask until the bottom of the meniscus aligns exactly with the calibration mark on the neck of the flask. Ensure the flask is at the specified temperature (e.g., 20°C, as mentioned for the precision).
- Mix Thoroughly: Stopper the flask and invert it several times (typically 15-20 times) to ensure the solution is homogenous and the sulfate concentration is uniform throughout the volume.
Resulting Solution Characteristics
As stated in the reference:
- The resulting solution is a Sulfate Standard Solution.
- It contains a precise concentration of 1000 μg/mL (micrograms per milliliter) of SO₄²⁻ ions.
- This concentration has a specified tolerance (e.g., ±7 μg at 20°C for the referenced product).
- This type of standard solution is specifically used with analytical instruments like ion-selective electrodes to calibrate them for measuring sulfate concentrations in samples.
This method ensures a known and verifiable concentration of sulfate ions, crucial for accurate analytical measurements.
