Demonstrating the laboratory preparation of carbon dioxide and identifying various physical and chemical properties of carbon dioxide.
Aim / Objective:
To demonstrate the laboratory preparation of carbon dioxide and to identify various physical and chemical properties of carbon dioxide.
Carbon dioxide, CO2, is one of two oxides of the element carbon and is the main product oxide of carbon formed from the combustion of hydrocarbon fuels. Carbon dioxide is present in the atmosphere and is produced by respiration and combustion. However it has a short time in this phase as it is consumed by plants during photosynthesis.
Some physical properties of carbon dioxide are:
- Soluble in water, ethanol and acetone
- Melting point is -78°C
- Boiling Point is -57°C
Some chemical properties of carbon dioxide are:
- Carbon dioxide is a covalent molecule.
- Carbon dioxide is an acidic oxide and reacts with water to form carbonic acid
CO2 + H2O = H2CO3
- Carbon dioxide reacts with alkalis to form carbonates and bicarbonates
CO2 + NaOH = NaHCO3 (sodium bicarbonate)
Sodium hydroxide (NaOH), dilute hydrochloric acid (HCl), Lime water, magnesium ribbon, calcium carbonate (marble chips), spatula, candle, universal indicator, thistle funnel, glass jar, U-tube, matches, flask, silica gel.
Method / Procedure:
- Add three spatulas full of calcium carbonate chips to the flask.
- Pour dilute hydrochloric acid into the top of the funnel; ensure that the liquid covers the tip of the funnel in the flask.
- Perform these various tests on the gas collected and note your results;
i. Observe the gas for color.
ii. Uncover one of the gas jars and use your hand to gently waft the gas towards the nostrils. Not e the smell.
iii. Add lime water to one of the gas jars and shake the mixture gently. Note the results.
iv. Uncover one of the gas jars and place a lit candle over the mouth of the jar. Note results.
v. Use a match to light a small piece of magnesium ribbon and place in gas jar. Note the results.
vi. Add a universal indicator to an uncovered jar and shake the mixture gently to determine its pH. Note your observations.
- Write the equation for the laboratory preparation of carbon dioxide.
>>>CaCO3(s) + 2HCl(aq) = CaCl2(aq) + H2O(l) + CO2(g)
- State some uses of carbon dioxide.
>>> Carbon dioxide is used in fire extinguishers
>>>Also used to produce carbonated drinks e.g. soft drinks and soda water.
>>>Carbon dioxide in the form of dry ice is used in the winemaking process to cool down grapes to help prevent spontaneous fermentation. This use of dry ice, instead of regular water ice, does not add any additional water that may decrease the sugar concentration in the grape and hence the alcohol concentration in the finished wine.