This is due very soon, please help!!!
Describe how you would prepare the following two solutions. Be sure to include the type of glassware which you would use and as much detail as necessary for someone to actually prepare the solution using good laboratory technique.
• 250 mLs of a 5% NaCl (w/v) from solid NaCl
• 250 mLs of 3 M HNO3 from concentrated nitric acid which is 15.8 M
To prepare 250 mL of a 5% NaCl (w/v) solution from solid NaCl, follow these steps:
1. Calculate the amount of NaCl needed: 5% w/v means that for every 100 mL of solution, 5 grams of NaCl need to be dissolved. Therefore, for 250 mL of solution, you will need (5 grams/100 mL) x 250 mL = 12.5 grams of NaCl.
2. Prepare a clean and dry 250 mL beaker or Erlenmeyer flask. Ensure that the glassware is free from any contaminants.
3. Weigh out 12.5 grams of solid NaCl using a analytical balance. Use a weighing boat to prevent contamination of the balance and transfer the NaCl into the beaker or flask.
4. Add a small volume of distilled water, around 50 mL, to the beaker or flask with the NaCl. Start stirring the mixture gently with a glass rod or a magnetic stir bar.
5. Continue stirring until all the NaCl is dissolved in the water. It may take some time and gentle heating can be used to speed up the dissolution process if necessary. Make sure not to boil the solution.
6. Once all the NaCl is dissolved, add additional distilled water gradually, while stirring, until the final volume reaches 250 mL. The volume can be adjusted using a graduated cylinder if needed.
7. Mix the solution thoroughly to ensure uniformity.
8. You now have 250 mL of a 5% NaCl (w/v) solution.
To prepare 250 mL of a 3 M HNO3 solution from concentrated nitric acid (15.8 M), follow these steps:
1. Calculate the amount of concentrated nitric acid needed to prepare the desired solution. A 15.8 M nitric acid solution means there are 15.8 moles of HNO3 per liter. To prepare a 3 M solution, you need to dilute it by a factor of 15.8 M / 3 M = 5.27.
2. Measure 50 mL of the 15.8 M nitric acid using a measuring cylinder and pour it into a clean and dry 250 mL beaker or Erlenmeyer flask. Be cautious and use proper safety precautions when handling concentrated acids.
3. Add distilled water slowly to the beaker or flask while stirring continuously. Start with small amounts of water, around 100 mL, and gradually add more until the final volume reaches 250 mL.
4. Mix the solution thoroughly to ensure uniformity.
5. You now have 250 mL of a 3 M HNO3 solution.
Always remember to use proper safety procedures when working with chemicals and consult the safety data sheets (SDS) for any hazardous materials.
To prepare the two solutions, you will need the following materials and glassware:
For 250 mL of a 5% NaCl (w/v) solution:
- Solid NaCl (sodium chloride)
- A 250 mL volumetric flask
- A balance or scale
- Distilled water
For 250 mL of 3 M HNO3 (nitric acid) from concentrated nitric acid:
- Concentrated nitric acid (15.8 M)
- A 250 mL volumetric flask or beaker
- Distilled water
- Safety equipment like gloves and goggles
Here's how you can prepare each of the solutions:
1. 250 mL of a 5% NaCl (w/v) from solid NaCl:
- Measure 5% of the desired volume (250 mL) using the formula: Mass of NaCl = (5/100) * volume * density of NaCl. The density of NaCl is typically around 2.165 g/mL.
- Use a balance or scale to accurately measure the required mass of NaCl.
- Place the measured NaCl into the 250 mL volumetric flask.
- Add distilled water to the flask gradually, swirling gently to dissolve the NaCl completely.
- Continue adding distilled water until the total volume reaches the calibration mark on the flask (250 mL). Be careful not to exceed the mark.
- Cap the volumetric flask and invert it several times to ensure thorough mixing.
2. 250 mL of 3 M HNO3 from concentrated nitric acid:
- Wear appropriate protective clothing, gloves, and goggles due to the hazardous nature of concentrated nitric acid.
- Measure out 250 mL of concentrated nitric acid (15.8 M) using a measuring cylinder or pipette. Be cautious and work in a well-ventilated area.
- Pour the measured amount of concentrated nitric acid into a 250 mL volumetric flask or beaker.
- Gently add distilled water to the flask while stirring to dilute the concentrated acid.
- Continue adding distilled water until the total volume reaches the calibration mark on the flask (250 mL). Be cautious and avoid any splashes.
- Mix the solution thoroughly by swirling or stirring.
Remember, safety precautions are important when working with chemicals, especially concentrated acids. Always wear appropriate protective equipment, work in a well-ventilated area, and handle the substances carefully to prevent accidents or injuries. If you are not familiar with laboratory techniques or working with hazardous substances, it is advisable to seek assistance or guidance from an experienced lab technician or instructor.