If there are 10 groups performing an experiment and each group needed 25.0 mL of 0.250 M NaOH, how would you prepare the NaOH solution for the whole lab using the NaOH pellets?
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To prepare the NaOH solution for the whole lab using NaOH pellets, you will need to calculate the amount of NaOH pellets and water required. Here's how you can do it:
1. Determine the total volume of the NaOH solution needed for all 10 groups. Since each group needs 25.0 mL, the total volume required would be 10 groups * 25.0 mL/group = 250 mL.
2. Calculate the moles of NaOH required using the given molarity (0.250 M) and volume (250 mL). Molarity (M) is defined as moles of solute divided by the volume of the solution in liters. So, we can use the formula Moles = Molarity * Volume (in liters).
Moles = 0.250 M * 0.250 L = 0.0625 moles
3. Convert the moles of NaOH to grams using its molar mass. The molar mass of NaOH is 22.99 g/mol for sodium (Na) + 16.00 g/mol for oxygen (O) + 1.01 g/mol for hydrogen (H).
Mass = 0.0625 moles * (22.99 g/mol + 16.00 g/mol + 1.01 g/mol) = 2.275 g
So, you will need 2.275 grams of NaOH pellets.
4. Dissolve the NaOH pellets in water to make the desired volume (250 mL) of the NaOH solution.
- Measure an appropriate amount of distilled water. Take into account that the volume of the NaOH pellets will add to the final volume of the solution.
- Place a container on a balance and tare it (reset the weight to zero).
- Carefully add the NaOH pellets to the container, making sure not to touch them with your hands.
- Add the measured amount of water to the container with the NaOH pellets.
- Stir the solution gently until the pellets are completely dissolved.
- Transfer the solution to a clean and properly labeled container (e.g., a bottle) for storage and use in the lab.
Remember to always handle NaOH with caution, as it is a strong base and can cause burns or harm if not properly handled. Use appropriate safety equipment such as gloves and goggles when working with it.