From our results, it was evident that rain water became temporarily hard when calcium ions (in the form of calcium carbonate) were dissolved in it. This could be told because when rain water with the calcium carbonate contained in it, produced no lather when it was reacted, with soap. However when thsi sample of distilled water was boiled, then good lather was produced, meaning that the rain water became soft again once it was boiled. Therefore, rain water is temporarily hard. The initial hardness was caused because of the calcium ions that were dissolved within the dilute hydrochloric acid: HCl + CaCO3 –> Ca(HClO3)
This hardness, however, is only temporary, and the water sample can be made soft again by boiling. This is because calcium carbonate is insoluble in water, which a characteristic that is similar for virtually all carbnates. Therefore, once boiled, it can be removed easily from the water. This means that calcium carbonate only causes temporary hardness once it is dissolved in rain water. However, when acid rain passes over rocks such as gypsum and dissolve calcium sulphate (which is soluble in water) permanently hard water is caused, which can only be reversed by the use of an ion exchange resin or by the addition of sodium carbonate.
In industry, boiling is not a preferred way of removing temporary hardness as is a very expensive method which wastes too much energy. So, in industry either adding sodium carbonate or using an ion exchange resin is preferred. The distilled water was used as a control. As predicted this poor water was not hard and produced no lather when reacted with soap before and after being boiled. Our findings confirm that acid rain does cause hardness in water when calcium ions are dissolved in it, and that the type of hardness caused (temporary or permanent) depends on the type of calcium or magnesium ion that is dissolved in it.
In a global aspect, hard water can cause limescale and block pipes, making them inefficient. It also wastes soap, as no lather can be produced in the presence of hard water, as we have found in this experiment. The other problems that the Earth faces because of acid rain, other than the fact that it causes hardness in water, is that it has a negative effect on wildlife, as it can kill plant and animal life, and causes acidic soil and water (in lakes, rivers etc) and damages buildings. PART III – BIOLOGY Question: Does carbon dioxide affect plant growth? Aim To determine the effects that carbon dioxide has on the growth of plants.
In this experiment, we are investigating the effect of carbon dioxide on the growth of beans, specifically. It is also part of our aim to confirm that carbon dioxide really is a greenhouse gas. Hypothesis I predict that the plant inside the container with the carbon dioxide will grow poorly, since the atmosphere within the container will contain a high proportion of carbon dioxide, and a low proportion of oxygen (which is the gas required for respiration). Because of this, the growing beans will not be able to respire and grow, and could even die within a few days.
This is the formula for respiration: 6O2 + C6H12O6 –> 6CO2 + 6H2O Plant seeds can not photosynthesise during their growth, since they have no leaves, which is the main site where photosynthesis occurs. Since they have no leaves, they have little or no palisade cells containing chloroplasts, which contain the green pigment chlorophyll. Chlorophyll is the pigment which absorbs light and uses it for photosynthesis. Without this, photosynthesis cannot occur as light cannot be absorbed into the leaf without it. This is the equation for photosynthesis: 6CO2 + 6H2O –> C6H12O6 + 6O2
Because of the increased amount of carbon dioxide inside the beaker and the early stage of life that the plant is in, it will neither be able to respire nor photosynthesise easily. For this reason, the plant will have poor growth and will eventually die because of its inability to get its nutrients required for survival. Other beans will be placed in a container with no carbon dioxide being produced inside it, in order to be used as a control and to form a comparison between the lengths of these plant and the lengths of the plants in the container with the carbon dioxide.
Since, this container will contain normal levels of oxygen and carbon dioxide, the plant will be able to respire easily, and will grow at a normal rate, producing a long shoot. The beans in his container will still be alive by the end of our experiment and will benefit from the favourable conditions. Finally, since we will be recording the day-to-day temperature, I predict that the temperature inside the container without carbon dioxide will remain constant throughout our experiment, whereas the temperature inside the container with the carbon dioxide will increase as the days progress, because carbon dioxide is a greenhouse gas.
This means that carbon dioxide will allow heat energy from the light source to enter the container, but will not allow it to leave, and will reflect it back inside the container, which will eventually cause a gradual increase in temperature, as more heat builds up. This is exactly what is happening in the world’s atmosphere today as the heat energy from the Sun becomes trapped in the atmosphere since the carbon dioxide has allowed it to enter, but will not allow it to leave.
From our results, it was evident that the beans inside the container without the carbon dioxide being produced everyday grew much more than the beans inside the container in which carbon dioxide was being produced. This was because the beans inside the container with the excess of carbon dioxide were unable to respire properly, because of the lack of oxygen inside the container. These adverse conditions actually killed the beans, which stopped growing after day 2, and turned into an unhealthy, mouldy colour.
On the other hand, the beans inside the other container which contained normal conditions grew normally and one of them even grew a shoot of length 8. 4cm, which was about 17 times the growth inside the other container. The plants inside this container, without much carbon dioxide grew more in days 1-2 than the plants in the container with the carbon dioxide grew for the entire experiment. The data shows clearly just how much difference there was in the growth between the growth of the beans inside the container with the carbon dioxide being produced and the growth of the beans inside the other, control container.
Our findings, show that carbon dioxide really does have an effect on plant growth, and has the ability to (when in high concentration), to stop plant growth completely (as was seen in this experiment). This experiment highlights just what a danger a greenhouse gas like carbon dioxide is to the atmosphere in high concentrations, and what is more worrying is that the amount of carbon dioxide and other harmful greenhouse gases are gradually increasing in the atmosphere.
Even in low concentrations, carbon dioxide and other polluting gases can be held accountable for the increasing number of human diseases such as asthma. It is also a great danger to plants and can be very harmful to them, as clearly demonstrated by this experiment. As, we have also learned from this experiment, it also traps heat rays from the Sun, prevents it from re-entering space and keeps it within the Earth’s atmosphere, causing global warming (the greenhouse effect).
Another problem arising from excess carbon dioxide being present in the atmosphere is that it causes acid rain once the carbon dioxide gets dissolved in atmospheric precipitation to form dilute carbonic acid (which is acid rain). Acid rain affects the pHs of soil, lakes, rivers etc. and has a negative effect on architectural structures due to its corrosive nature. This experiment clearly emphasizes just how important it is for the world to reduce these carbon dioxide emissions, and some of the long-term problems that may arise if carbon dioxide continues to be released into the atmosphere at the rate that it is being produced today.