Experiment: Influence Of Citric Acid In Water On Woolworths Plastic Bag

When first thinking about the subject of this experiment I had several options each very different in their own way and would all produce very different outcomes. I had finally decided after a few days of research and discussion with Mrs Airth that I will be testing “what different ratios of citric acid will do to a plastic bag”. This investigation took place over 19 days starting on the 8th of April and ending on the 26th and the results were actually very interesting and abstract from my first initial thoughts. The outcome of this investigation showed that the plastic bags placed in the test tubes became not only softer in colour but also texture in the substances that had a higher ratio of acid.

Before even gathering any of the materials that I need for this experiment I did quite a bit of research not only on the type of acid that I was interested in using but also the specific type of plastic bag I would be using. Seeing as I used the Woolworths multi use plastic bag I looked to their website for facts and information about what it was made up of. The actual Woolworths website didn’t offer any substantial information about what type of plastic was used in these bags but they did claim that they are made from 80% recycled plastics making them stronger and more durable for carrying heavy groceries. Coming into this experiment I already knew definitely that the plastic bag used would not even be close to dissolving no matter what acid I used but the fact that the bag is made up from multiple types of plastic I did suspect that it could be weaker than normal polyethylene.

I also did a very large amount of research on citric acid and the properties it had on different types of materials. The origin of this type of acid comes organically from citrus fruits and is usually used on sweets and candies as it gives a very sour taste. The main use for this acid other than for consuming is to clean. Seeing as citric acid is a very efficient bacteria killer. It is used to remove mildew, mould and s great for disinfecting and cleaning around the house. Citric acid is also very good removing soap scum, hard water stains, calcium deposits, lime and rust. But none of the information found had anything to do with what citric acid would do to this type of plastic bag which made this investigation even more interesting to conduct.

The aim of this whole investigation was to see exactly what different ratios of citric acid in water would do to a Woolworths plastic bag. I also included in this experiment a clean test tube of water so I would have something to refer back to and compare to those test tubes that did have small or large ratios of acid in them.

My hypothesis for this experiment being conducted was that the higher ratio of acid mixed in with the water the faster or more drastic the plastic will either weaken and change. As stated before I went into this experiment knowing that this type of plastic wont dissolve but I was more than curious to see how or if the citric acid would do anything to these small scraps of plastic cut from a shopping bag.