How to find the molarity of the acid?

Safety

This experiment sodium hydroxide will be used this is a strong alkaline and can damage the skin and can also damage the eyes if splashed in them so during the experiment so I will be using safety goggles during all times I will also wear rubber gloves to protect the skin from any contact with the sodium hydroxide.

Equipment

This is the equipment that I will be using:

Pipette, beaker, a white ceramic tile, a clamp and stand, burette, methyl orange. And a 250 ml standard measuring flask and some electronic scales.

Method

In this experiment I want to find out the concentration of the hydrochloric acid (HCl) with the concentration of the NaOH and used a indicator to tell me when neutralization had taken place.

I had to gather a pipette, beaker, a white ceramic tile, clamp and stand, burette, methyl orange and a 250 ml standard measuring flask and some electronic scales. I got some NaOH and weighed out 3.3 grams on the electric scales. I poured 250 ml of distilled water into my standard measuring flask and then placed the NaOH pellets into the 250 ml of distilled water the pellets are hydroscopic and absorb water from the atmosphere around them so I had to move quickly at this stage.

I set up my clamp and stand and clamped the graduated burette and I put on my goggles. I measured out 25 ml of HCl and put this into the pipette. I then used the pipette to measure about 25 ml of NaOH and then this was poured this into a conical glass. I put three drops of methyl orange to the NaOH and stirred it around until the solution changed orange. I placed the conical glass under the burette and placed a white tile underneath the conical glass to help me watch me the indicator change colour. I made a results table the first time this experiment would be conducted it would be the rough to give me an indication of when to stop the burette then I would repeat it three times. While the HCl was being gradually dropped into the conical flask I had to continually had to swirl the NaOH and methyl orange solution until the colour changed from yellow to orange. When I went past this point of adding too much HCl the colour would go to red this was known as the end point. I found on the first time of conducting this experiment I found at around about 17cm3 was where I needed to stop graduating the solution into the conical flask.

Results table

Rough

st attempt

2nd attempt

3rd attempt

7.8

7.1

7.0

7.1

The average was 17.06

mol of NaOH = 40 g

x mol of NaOH = 3.3 g

3.3 g /40 g = x

0.0825 = x mol

0.0825 mol of NaOH dissolved in 250 ml (0.25dm 3) distilled water

0.25 dm 3 =0.0825 mol

dm 3 = x mol

0.0825 x 1 /0.25 = x mol

=0.33 mol /dm3

Finding the concentration of hydrochloric acid

MAVA = a MA x 0.01706 = 1

MBVB = b 0.33 x 0.025 = 1

MA x 0.01706 x 1 = 0.33 x 0.025 x 1

MA x 0.01706 = 0.00825

MA = 0.00825

0.01706

MA = 0.48 mol/dm3

Conclusion

I found out that the concentration of hydrochloric acid is 0.48 mol/dm3 . the experiment was repeated three times and the results obtained did not differ from no more than 0.1 . this proved that the experiment was carried out carefully and the results were accurate.

Evaluation

In this experiment I feel that I should have dried out the conical flask after cleaning it out with the distilled water as this has most likely affected the concentration of the NaOH. I should have also cleaned and dried out the graduated burette as this also could have affected the final results but this would have proved to be too difficult as it was very narrow and long I don't think that I could have read a tenth of a cc on the graduated pipette of the water that I could not have dried out. All the experiments were conducted on the same day so the room temperature stayed the same.

Alex Mcghie