A LABORATORY PROTOCOL ON THE ENVIRONMENTAL SCIENCES EXPERIMENT CARRIED OUT BY SPANISH  STUDENTS OF ESCUELA PROFESIONAL “LA SALLE” PATERNA (VALENCIA)

CO2 IN OUR LIVES

Introduction

Carbon dioxide is a gas that pollutes the environment and it is the one that increases the greenhouse effect the most. In other words, it increases the retention of heat in the atmosphere and it generates global warming.

Carbon dioxide is not toxic to living beings because it is a gas that we exhale, but in high concentrations, more than 30.000 ppm, it can produce suffocation.

In plants, a high concentration of carbon dioxide causes a reduction in photosynthesis

Objectives

We have four experiments to carry out:

  1. CO2: For all the following experiments we need CO2 and we are going to produce it using vinegar and bicarbonate;the greater the quantity of vinegar and bicarbonate the greater will be the concentration of CO2.
  1. SEA AND OCEANS: First, we thought about simulating a sea or an ocean with a high concentration of CO2. in order to do this we must confirm whether or not the CO2 changes the acidity of the water using bromothymol blue. The hypothesis is: the yellower the water is, the more acidic it will be. Finally, if the beaker that has water with CO2 is yellow this means that some marine species cannot survive and they will become extinct in the future.
  1. AIR:We want to see if a large amount of CO2 can warm up the air of the planet and therefore explain the melting of the Earth’s Poles, despite the differences in the North and South Poles. The hypothesis is: the more carbon dioxide the air has, the quicker the atmosphere will warm up.
  1. PLANTS: Additionally, like the solutions to the previous problems, we are going to recreate the reaction of aquatic plants with a high concentration of carbon dioxide.Plants are the solution because during daytime via photosynthesis they change CO2 to oxygen, whereas at night they change oxygen to CO2. We have chosen aquatic plants because in the water we can easily see the oxygen bubbles and the hypothesis here is that the more carbon dioxide the plant consumes, the more oxygen it will produce.

Materials

CO2

  • 1 plastic bottle with the cap (125ml)
  • Scissors
  • 2 latex tubes, one longer than the other
  • Scales
  • Petri dish
  • Test tube
  • Funnel

SEA AND OCEAN

  • 2 beakers
  • Scales
  • Petri dish
  • Tablespoon

AIR

  • 2 bottles
  • 2 thermometers
  • Sticky tape
  • Foil

PLANTS

  • Large transparent pot
  • Aquatic plant
  • Paper
  • Scales
  • Petri dish

Products

CO2

  • Vinegar (80ml/50ml)
  • Bicarbonate (20g/50g)

SEA AND OCEANS

  • CO2 (80ml and 50g) in one beaker
  • 3 drops of bromothymol blue in each beaker
  • 100ml water in each beaker
  • 5g salt in each beaker

AIR

  • CO2 (50ml and 20g)

PLANTS

  • CO2 (80ml and 50g)
  • Water
  • 18g bicarbonate

Experimental procedure

CO2

  1. Measure 80ml or 50ml of vinegar in a test tube.
  2. Measure 50g or 20g of bicarbonate with the scales and a petri dish.
  3. Drill into the cap of the plastic bottle with the scissors and put one end of the latex tube in the hole.
  4. Put the bicarbonate inside the plastic bottle using the funnel.
  5. Quickly add the vinegar and close the bottle.
  6. Put the other end of the latex tube wherever necessary
  7. Repeat this for each experiment.

SEA AND OCEAN

  1. Put 100ml of water in each beaker.
  2. Measure 5g of salt and put it in each beaker.
  3. Dissolve the salt in each beaker
  4. In one of them put CO2 (80ml, 50g and use the short latex tube).
  5. Add3 drops of bromothymol blue to each beaker.
  6. Observe the colour of each beaker and the difference.

AIR

  1. Use 2 glass bottles.
  2. In one of them add CO2 (50ml, 20g).
  3. Cover both bottles with foil and stick it down with sticky tape.
  4. In each bottle, pierce the paper with a thermometer.
  5. Put both bottles in the sun and wait.
  6. Then observe the air temperature of the bottles. Which one is hotter than the other?

PLANTS

  1. Put the aquatic plant in the large transparent pot.
  2. Fill the pot with enough water to cover the plant.
  3. Add the CO2 (80ml, 50g using the longer latex tube) to the water .
  4. Measure 18g of bicarbonate with the scales and the petri dish.
  5. Add the 18g of bicarbonate to the pot .
  6. Cover the pot with the paper.
  7. Put the plant in the sun.
  8. Wait and see if photosynthesis occurs and look for oxygen bubbles under the water.

Results

CO2

We got a high concentration of CO2 from the latex tube; and the reaction is effective immediately.

SEA AND OCEANS

We had one beaker that represented typical seas and oceans without a high quantity of CO2 and this was blue,meaning it is basic..However,The other beaker, with a lot of CO2,is yellower meaning it is more acidic.

AIR

In this experiment we had 2 bottles, one of them with CO2 and the other without. At first the T bottle without CO2 was hotter than the other one, but, as time passed, the bottle with CO2 became hotter than the other one.

PLANTS

After some time had passed we could see small oxygen bubbles around the plant, meaning that photosynthesis had taken place and the CO2 was changing to oxygen.

Conclusions

Finally, ,we arrived at the conclusion that all the hypotheses are right and CO2 pollution is causing some marine species to become extinct because it changes the acidity of the water. Also, it can cause the melting of the Earth Poles because we have seen that the CO2 increases water temperaturer. The solutionis plants;they can change the concentrations of CO2 to oxygen. However, people are looking for other more complicated solutions, and they are ignoring this easys olution.

Questions

Why do vinegar and bicarbonate cause CO2?

Because a chemical reaction takes place.

Vinegar is an acid (called acetic acid), and baking soda is a base.

When an acid and a base come together, a chemical reaction occurs. Some may explode, but in this case the reaction is not as violent.

Is this one: vinegar + sodium bicarbonate -> sodium acetate + water + CO2

Why is the air without CO2 hotter than the other air at first, but then the air with CO2 ends up being hotter than the other air?

How does bromothymol blue work?

Below pH7, the indicator is yellow, but if the pH becomes basic, the -OH groups deprotonate and a C=O double bond can form.

As a result, the molecule’s conjugate system (that of all its resonant double bonds) changes enough so that the electrons no longer absorb the same photons, and the solution turns from yellow to bluish.

If, on the other hand, the pH is much below 7, the colour of the indicator changes from yellow to red. The change in the conjugate system is due to the protonation of the -OH groups to -OH2+.