This question appears to suggest that you want exactly 5ml of 0.2M of NaOH. Since measurement of small quantities are involved, the method outlined below will involve significant percentage uncertainties. Nevertheless we must carefully carry it out to obtain a solution close to expectation.
Calculations:
0.2M NaOH means 0.2 mol/litre. Therefore 5ml of this NaOH solution must contain (0.005 litre x 0.2 mol/litre)=0.001 mole.
By definition of number of moles, the mass of NaOH required =(0.001 x 40)g=40mg.
Preparation:
Using electronic balance with least count of 0.01mg or 0.1mg, measure exactly 40mg of the NaOH into a clean small funnel on a small volumetric flask. Then run exactly 5ml of clean water from a good burette, with a least count of 0.01 ml, to carefully wash down into the flask all the NaOH in the funnel. Make sure the watch glass used to weigh the 40mg is first washed with part of the 5ml water into the funnel. This will ensure that all the 40mg of NaOH are used. Great care must be taken not to lose any drop of water ran from the burette to dissolve the NaOH crystals. After running the 5ml clean water to dissolve all the NaOH, allow the flask to stand for about 5 minutes to ensure no liquid remains in the funnel. Ensuring no drop of liquid remains at the tip of the funnel carefully remove it from the flask. Cork your flask and give it a gentle swirl to ensure that all solid NaOH dissolve.
Why must one want to prepare only 5ml of the solution?
Only a very small supply of the NaOH available will necessitate the above method with significant uncertainty. If there is no supply constraint with respect to the NaOH, then the best thing to do is to prepare a much larger and economic volume of the solution. This way will certainly minimize the uncertainties in measurement.
This question appears to suggest that you want exactly 5ml of 0.2M of NaOH. Since measurement of small quantities are involved, the method outlined below will involve significant percentage uncertainties. Nevertheless we must carefully carry it out to obtain a solution close to expectation.
Calculations:
0.2M NaOH means 0.2 mol/litre. Therefore 5ml of this NaOH solution must contain (0.005 litre x 0.2 mol/litre)=0.001 mole.
By definition of number of moles, the mass of NaOH required =(0.001 x 40)g=40mg.
Preparation:
Using electronic balance with least count of 0.01mg or 0.1mg, measure exactly 40mg of the NaOH into a clean small funnel on a small volumetric flask. Then run exactly 5ml of clean water from a good burette, with a least count of 0.01 ml, to carefully wash down into the flask all the NaOH in the funnel. Make sure the watch glass used to weigh the 40mg is first washed with part of the 5ml water into the funnel. This will ensure that all the 40mg of NaOH are used. Great care must be taken not to lose any drop of water ran from the burette to dissolve the NaOH crystals. After running the 5ml clean water to dissolve all the NaOH, allow the flask to stand for about 5 minutes to ensure no liquid remains in the funnel. Ensuring no drop of liquid remains at the tip of the funnel carefully remove it from the flask. Cork your flask and give it a gentle swirl to ensure that all solid NaOH dissolve.
Why must one want to prepare only 5ml of the solution?
Only a very small supply of the NaOH available will necessitate the above method with significant uncertainty. If there is no supply constraint with respect to the NaOH, then the best thing to do is to prepare a much larger and economic volume of the solution. This way will certainly minimize the uncertainties in measurement.
This question appears to suggest that you want exactly 5ml of 0.2M of NaOH. Since measurement of small quantities are involved, the method outlined below will involve significant percentage uncertainties. Nevertheless we must carefully carry it out to obtain a solution close to expectation.
Calculations:
0.2M NaOH means 0.2 mol/litre. Therefore 5ml of this NaOH solution must contain (0.005 litre x 0.2 mol/litre)=0.001 mole.
By definition of number of moles, the mass of NaOH required =(0.001 x 40)g=40mg.
Preparation:
Using electronic balance with least count of 0.01mg or 0.1mg, measure exactly 40mg of the NaOH into a clean small funnel on a small volumetric flask. Then run exactly 5ml of clean water from a good burette, with a least count of 0.01 ml, to carefully wash down into the flask all the NaOH in the funnel. Make sure the watch glass used to weigh the 40mg is first washed with part of the 5ml water into the funnel. This will ensure that all the 40mg of NaOH are used. Great care must be taken not to lose any drop of water ran from the burette to dissolve the NaOH crystals. After running the 5ml clean water to dissolve all the NaOH, allow the flask to stand for about 5 minutes to ensure no liquid remains in the funnel. Ensuring no drop of liquid remains at the tip of the funnel carefully remove it from the flask. Cork your flask and give it a gentle swirl to ensure that all solid NaOH dissolve.
Why must one want to prepare only 5ml of the solution?
Only a very small supply of the NaOH available will necessitate the above method with significant uncertainty. If there is no supply constraint with respect to the NaOH, then the best thing to do is to prepare a much larger and economic volume of the solution. This way will certainly minimize the uncertainties in measurement.
This question appears to suggest that you want exactly 5ml of 0.2M of NaOH. Since measurement of small quantities are involved, the method outlined below will involve significant percentage uncertainties. Nevertheless we must carefully carry it out to obtain a solution close to expectation.
Calculations:
0.2M NaOH means 0.2 mol/litre. Therefore 5ml of this NaOH solution must contain (0.005 litre x 0.2 mol/litre)=0.001 mole.
By definition of number of moles, the mass of NaOH required =(0.001 x 40)g=40mg.
Preparation:
Using electronic balance with least count of 0.01mg or 0.1mg, measure exactly 40mg of the NaOH into a clean small funnel on a small volumetric flask. Then run exactly 5ml of clean water from a good burette, with a least count of 0.01 ml, to carefully wash down into the flask all the NaOH in the funnel. Make sure the watch glass used to weigh the 40mg is first washed with part of the 5ml water into the funnel. This will ensure that all the 40mg of NaOH are used. Great care must be taken not to lose any drop of water ran from the burette to dissolve the NaOH crystals. After running the 5ml clean water to dissolve all the NaOH, allow the flask to stand for about 5 minutes to ensure no liquid remains in the funnel. Ensuring no drop of liquid remains at the tip of the funnel carefully remove it from the flask. Cork your flask and give it a gentle swirl to ensure that all solid NaOH dissolve.
Why must one want to prepare only 5ml of the solution?
Only a very small supply of the NaOH available will necessitate the above method with significant uncertainty. If there is no supply constraint with respect to the NaOH, then the best thing to do is to prepare a much larger and economic volume of the solution. This way will certainly minimize the uncertainties in measurement.
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