To make a standard calcium chloride (CaCl₂) solution, follow these steps:
Steps for Preparing a 1 M Calcium Chloride Solution (approximately)
This method prepares approximately a 1M solution, but osmolarity should be checked and adjusted.
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Gather Your Materials: You'll need:
- Calcium Chloride (CaCl₂) - anhydrous form is preferred for accuracy, but the dihydrate form can also be used (adjust calculations accordingly).
- Distilled water (H₂O)
- A suitable container (e.g., a beaker or flask) with a volume of at least 1 liter
- A weighing scale
- A stirring rod or magnetic stirrer
- A volumetric flask (1 L)
- An osmometer (for final adjustment)
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Calculate the Required Mass:
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The molecular weight of anhydrous CaCl₂ is approximately 110.98 g/mol.
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To make a 1 M solution in 1 liter, you need 1 mole of CaCl₂.
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Therefore, you'll need approximately 110.98 grams of anhydrous CaCl₂ per liter. For the solution described in the prompt, this is aiming for a final osmolarity near 1000 mmol/kg. The prompt calls for 58 g in 1 L which is approximately 0.52 M.
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If using Calcium Chloride Dihydrate (CaCl₂ · 2H₂O): The molecular weight is approximately 147.01 g/mol. Therefore, you'll need approximately 147.01 grams of CaCl₂ · 2H₂O per liter for a 1M solution. For a 0.52M solution, you'd need approximately 76.44 grams.
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Important Note: The original question reference implies a targeted osmolarity. This method is designed to obtain that.
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Dissolve the Calcium Chloride:
- In a suitable container (larger than 1L), add approximately 800 mL of distilled water. This prevents exceeding the final volume and allows for adjustments.
- Carefully weigh out 58g (according to reference) of Calcium Chloride.
- Slowly add the CaCl₂ to the water while stirring continuously. This helps to dissolve the salt more quickly and prevents clumping.
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Adjust Volume to 1 Liter:
- Once the CaCl₂ is completely dissolved, transfer the solution to a 1 L volumetric flask.
- Add distilled water to the flask until the solution reaches the 1 L mark. Ensure the bottom of the meniscus aligns with the mark at eye level.
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Verify and Adjust Osmolarity (Critical Step):
- Use an osmometer to measure the osmolarity of the solution. The target osmolarity, according to the prompt, is approximately 1000 mmol/kg.
- If the osmolarity is below 1000 mmol/kg: Carefully add small amounts of CaCl₂ to the solution, dissolve completely, and measure the osmolarity again. Repeat until the desired osmolarity is reached.
- If the osmolarity is above 1000 mmol/kg: Add distilled water to the solution, mix well, and measure the osmolarity again. Repeat until the desired osmolarity is reached.
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Mix Thoroughly:
- After adjusting the volume and osmolarity, thoroughly mix the solution to ensure uniformity.
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Storage:
- Store the calcium chloride solution in a clean, airtight container at room temperature or refrigerated. Label the container clearly with the concentration (approximately 0.52 M as per the prompt's amounts) and the date of preparation.
Important Considerations:
- Always use distilled or deionized water to avoid contamination.
- Wear appropriate personal protective equipment (PPE), such as gloves and eye protection, when handling chemicals.
- Calcium chloride can generate heat when dissolved in water (exothermic reaction). Add it slowly and stir to dissipate the heat.
- The exact concentration of the solution should be verified using appropriate analytical techniques if highly precise concentrations are required.
- Always consult the Material Safety Data Sheet (MSDS) for calcium chloride for specific safety information and handling precautions.
