Experiments To Determine The Effect Of Acids & Bases Essay, Research Paper

Experiments to Determine the Effect of Acids & Bases on Different Indicators and the pH of Common Cleaning Agents

The aim of the first set of experiments is to find out and record the colour changes that are observed after a certain indicator is mixed with acids and bases to form a colour reaction. Once the selected indicator has been mixed with a acid that is both weak and strong and a base/alkali that is both weak and strong we are to record the colour and choose another indicator. The purpose of this experiment is to find out what indicators are sensitive to what areas of the pH colour spectrum, while also looking how Universal Indicator covers most areas of the pH spectrum generally but much less accurately. The aim for the second experiment is to find out the pH levels of different domestic cleaners and then studying the results. The main purpose of this experiment is that it gives an insight to whether cleaners are basic or acidic for our general knowledge. The only predictions I made on the first experiment was that know what colour would be shown after the reaction with the Universal Indicator. This was because I already had the pH chart for this indicator with me to confirm colours vs. pH. I did make a prediction on the second experiment which was that almost all of the cleaners would have a different pH level. I thought this because all of the domestic cleaners are suited to remove different things such as grease and mould and for this you would need a different pH level.

Materials:

* Bottles of Different Indicators

* Strong and Weak Acids

* Strong and Weak Bases

* Rack with Test Tubes

* Containers of Different Domestic Cleaners

* Ceramic Tile

* Universal Indicator pH Chart

* Lab Coat

* Safety Goggles

* Small Quantity of Paper Towel

Method:

To start off the experiment a lab coat and safety goggles were worn for safety reasons. Then a white tile was placed on the bench and then one drop of the chosen strong acid, Hydrochloric Acid 2M ( HCI ) was placed on the tile using an eyedropper. Then one drop of Phenolphthalein was placed on the tile so that it landed in the previous drop of Hydrochloric Acid. This colour reaction was noted and then recorded on a results sheet. The tile was then placed under a fair quantity of water to clean it and then was dried off with some paper towel. Following the same steps as before one drop of the chosen weak acid, Sulfuric Acid 1M ( H2SO4 ) was placed on the tile using an eyedropper. Then one drop of Phenolphthalein was placed on the drop of Sulfuric Acid and the colour was noted and recorded on a results sheet. The tile was then washed after every pH sample to ensure that there was no contamination from other chemicals. The Phenolphthalein indicator was then tested with the chosen strong base, Sodium Hydroxide 2M ( NaOH ) and the chosen weak base, Sodium Hydroxide 1M. The indicators, Phenol Red, Methyl Red, Methyl Orange, Beomothymol Blue, Universal Indicator and Congo Red were then tested following the acids and bases as above. The only variation to this is that for Universal Indicator and Congo Red the weak base was Potassium Hydroxide ( KOH ).

In the second experiment, a white tile was placed on the bench together with a rack of test tubes. Approximately 30mls of water was placed in each of the six test tubes and then some domestic cleaning products were added to them. A small amount of bleach went in the first test tube, detergent in the second, Jiff Rinse Aid in the third and Ajax was placed in the fourth test tube. Then a small amount of Cloudy Ammonia was poured into the fifth test tube and Nifty was poured in the sixth test tube. At this point all of the six test tubes were rotated at high speed to make sure the solutes, which were the cleaners, had blended with the water to make a solution. Now a little amount of the diluted bleach was poured onto the tile and a drop of Universal Indicator placed on the solution. The colour was observed and compared to the colour spectrum displayed on the Universal Indicator pH chart. We cleaned the tile and went through this process for the detergent, Jiff’s Rinse Aid, Ajax, Cloudy Ammonia and Nifty. At this point two of the test tubes were thoroughly washed in the sink to avoid contamination and filled with approximately 30mls of water again. Now a small amount of Spray ‘n Wipe was placed in one test tube and a small amount of nail polish remover was placed in the other test tube. Both of these cleaning agents were poured separately on the tile and tested for their pH and had it recorded. Now we cleaned the tile and emptied the test tubes down the sink with large amounts of water to dilute the strong acids and bases.

Results:

The table below shows the results for the first experiment:

Indicator

Strong Acid Colour

Weak Acid Colour

Strong Base Colour

Weak Base Colour

Phenolphthalein

Hydrochloric Acid 2M

Remained

Transparent

Sulfuric Acid 1M

Remained

Transparent

Sodium Hydroxide 2M

N/A

Sodium Hydroxide 1M

N/A

Phenol Red

Hydrochloric Acid 2M

Light Orange

Sulfuric Acid 1M

Light Orange

Sodium Hydroxide 2M

N/A

Sodium Hydroxide 1M

N/A

Methyl Red

Hydrochloric Acid 2M

Dark Pink

Sulfuric Acid 1M

Dark Pink

Sodium Hydroxide 2M

Yellow

Sodium Hydroxide 1M

Yellow

Methyl Orange

Hydrochloric Acid 2M

Red

Sulfuric Acid 1M

Bright Pink

Sodium Hydroxide 2M

Dark Yellow

Sodium Hydroxide 1M

Dark Yellow

Beomothymol Blue

Hydrochloric Acid 2M

Yellow

Sulfuric Acid 1M

Yellow

Sodium Hydroxide 2M

Yellow

Sodium Hydroxide 1M

Light Blue

Universal Indicator

Hydrochloric Acid 2M

Light Red

Sulfuric Acid 1M

Pink

Sodium Hydroxide 2M

Dark Purple

Potassium Hydroxide 1M

Light Purple

Congo Red

Hydrochloric Acid 2M

Dark Blue

Sulfuric Acid 1M

Dark Blue

Sodium Hydroxide 2M

Red

Potassium Hydroxide 1M

Dark Orange

Unfortunately there was no time available to complete any of the bases for the indicators Phenolphthalein and Phenol Red. The table shows what indicators were used, the chemicals mixed with the indicators and the reaction of colour if there was one. There was quite a lot of different colours shown after mixing the acids and bases with different indicators. However you have to expect most indicators to only work in a certain colour range in the pH spectrum. Universal Indicator on the other hand deciphers the pH level into colours only between a pH of 4-12. This is because Universal Indicator is a mixture of many different indicators that only work within certain ranges. This allows the indicator to be used with most applications as it reacts with a variety of pH levels. Universal Indicator though, has a reduced accuracy as it is just a general indicator not one that focuses on smaller parts of the pH colour spectrum.

This table below is the results from experiment two:

Cleaning Agent

pH of Cleaning Agent in Water

Colour after reaction with agent and indicator

Bleach

8

Green

Detergent

7

Green/Yellow

Rinse Aid

8.5

Dark Green

Ajax

9.5-10

Light Purple

Cloudy Ammonia

9

Light Blue/Green

Nifty

5.5-5

Pink

Spray n’ Wipe

8

Dark Green

Nail Polish Remover

5

Pink

All of these cleaners when tested, were placed in water so that the Universal Indicator would work properly and give accurate results. I knew that all of the chemicals would have to have a different pH levels as I had predicted because they clean their own specific things such as grime, mould and dirt. It was surprising to note however that only two cleaning agents were acids and these were Nifty and the Nail Polish Remover. After looking at the bottle of Nifty it was clear that this was the only cleaner with a disinfectant so it is most likely an acid for this reason. Nail Polish Remover could be suspected of being an acid as it does have to break down the nail polish on ones’ finger nails. Apart from that the rest of the results are not unusual and could be expected.

Conclusion:

Both of the experiments were carried out quite smoothly and the results were quite pleasing. The results from experiment one show that all different indicators can be used for a more in-depth and accurate reading on the pH colour scale instead of using Universal Indicator which gives a general result. The most surprising and unusual event that happed was that Phenolphthalein was the only indicator that didn’t have a reaction with either the strong or weak acids. The experiment does not need to be done again but more of the experiment should have been completed. The second experiment was completed successfully with the acidic of two substances accounted for. The measurements of both experiments were accurate as both my partner and I judged the pH colours and decided on them mutually. I believe there could have been several errors in our experiment which I would have changed if I did the experiment a second time. I felt that the ceramic tile was washed satisfactorily and cleaned well but I think my group could have done a better job to ensure there was no contamination. I did notice that occasionally when I put a drop of a chemical on the tile that it would change colour as if there were still traces of an indicator still on the tile. I do not believe however, that this affected the results significantly though. After looking at the results for the first experiment I feel that the weaker acid and base should have been 0.1 Molar instead of 1 Molar. This was because the same colour was noticed for both the strong and weak acids and bases as if 1 Molar was still a strong concentration. This could however also be due to the range of indicators which might just give anything acidic one colour generally, instead of indicating strength of the acid. The last error I felt I might have made in this experiment is to change the weak base from Sodium Hydroxide 1M to Potassium Hydroxide 1M for Universal and Congo Red Indicator. The only reason I feel this is because the Potassium Hydroxide could be a more or less powerful acid than Sodium Hydroxide even though the solutions I used had the same Molar which was 1M. If I had kept the experiment uniform and constant then the results for those two indicators might have been different. The results from both experiments did agree with my predictions although my predictions were quite obvious and simple. After completing these two experiments successfully I think that it has led on to make a new experiment. The new experiment should look at how effective are different domestic cleaning agents against grime, mould, grease and dirt. Then you would be able to explore which cleaners give a general clean and which are suited and more effective against specific ‘nasties’.

M is the molecular weight in grams of the chemical in 1lt of water.