Why is lime water used to test for carbon dioxide

IDENTIFICATION OF GASES

EXPERIMENT 1:

DATA TABLE 1: GAS OBSERVATIONS

Step / Reaction

Observations

Reaction between Zinc and Hydrochloric Acid

Bubbled quickly and started to rise to the top. Gas is being released in the form of bubbles.

Hydrogen gas and Flame

A chemical reaction occurred where the gas was released quickly. With the smoldering toothpick you heard a popping sound. The flame went out.

Reactions that occurs when magnesium is in contact with hydrogen peroxide

Fizzing and bubbling and water is being displaced into hydrogen gas. The precipitate in the test tube turned a brownish color.

Oxygen gas and Smoldering Toothpick

Cloud of water vapor and gas. The toothpick glowed and was reignited.

Gas Mixture and Flame

The tooth pick glowed followed by a popping sound and then the flame went out.

Write a balanced chemical equation describing the reaction of zinc and hydrochloric acid.

Zn + 2HCI ZnCI2 + H2 (gas)

The gas produced is hydrogen, it burns with a popping sound. The decomposition of hydrogen peroxide produces oxygen gas.

What gas was produced by the reaction of zinc and hydrochloric acid? How did this gas behave in the presence of fire?

The gas that was produced by the reaction of zinc and hydrochloric acid was Hydrogen gas and zinc chloride. In the presence of fire, hydrogen explodes with a popping sound. The popping sound put out the flame.

What gas was produced by the decomposition of hydrogen peroxide? What happened when the smoldering toothpick cam in contact with the gas?

The decomposition of hydrogen peroxide produced Oxygen. When the smoldering toothpick came into contact with oxygen, it started burning again and slowly went out.

Compare the behavior of the mixture of gases with each solitary gas in the presence of flame.

Oxygen mixed with hydrogen; when exposed to a flame made a popping sound. A mixture of gases produce less amount of heat and solitary gases produce a high amount of heat.

Outline the procedures you would use to determine whether a gas sample was composed of hydrogen or oxygen.

A smoldering tooth pick was put in an inverted test tube of hydrogen; Hydrogen burns with a squeaky pop; if the tooth pick relights, the gas would be oxygen.

EXPERIMENT 2:

DATA TABLE 2: CARBON DIOXIDE REACTION OBSERVATIONS

Step/ Reaction

Observations

Ca(OH)2 + CO2

Fizzing occurred and the lime water turned cloudy with precipitate.

CO2 + BTB

The blue color solution (BTB) change to yellow.

CO2 + Flame

CO2 gas put out the flame on the toothpick quickly with a little release of smoke.

Ca(OH)2 + Antacid + water (gas)

Slight bubbling

Antacid + water(gas) + Smoldering Toothpick

Flame on the toothpick went out quickly releasing a little bit of smoke.

Ca(OH)2 + Breath

Lime water turned cloudy with a precipitate.

The chemical equation for the reaction of baking soda (sodium bicarbonate, NaHCo3) and vinegar (acetic acid, CH3COOH) may be written as two steps. Fill in the missing information for the chemical equation:

Step 1: _________ + __________ - CH3 COONa (aq) + H2CO3 (l)

Step 2: H2CO3 (l) - H2O (l) + ___________

Step 1: CH3COOH (aq) + NaHCO3 (s) CH3COONa (aq) + H2CO3 (l)

Step 2: H2CO3 (aq) - H2O (l) + CO2 (g)

If you add them both together :

CH3COOH(aq) + Na2CO3(s) —> CH3COONa(aq) + CO2(g) + H2O(l)

Write a chemical equation for the reaction of CO2 and limewater (Ca(OH)2). Write a physical description of the products formed.

Ca(OH)2 (aq) + CO2 (g) - CaCO3 (s) + H2O (l)

The reaction took place when a fizzing of CO2 gas released. The limewater turned cloudy with a precipitate. The calcium carbonate was produced as a salt which turned the solution into cloudy precipitate, which shows that CaCO3 is not soluble in water.

C) When the Bromothymol blue (BTB) was exposed to the CO2 gas, what color was the solution? Did the BTB indicate the presence of an acid or base? Explain your answer.

When the BTB was exposed to the CO2 gas, BTB is blue and becomes yellow. The color change indicates the presence of an acidic substance. The acid is H2CO3 carbonic acid.

CO2 + H2O —-> H2CO3

D) Did the reaction between the antacid tablet and the tap water produce hydrogen, oxygen or carbon dioxide gas? Support your answer with results from your work in both Exercise 1 and Exercise 2.

The reaction between the antacid tablet and the tap water produces carbon dioxide gas. The flame test in Exercise 1 with hydrogen peroxide produced a popping sound the flame reignited. In the presence of CO2 gas, the flame was put out on the toothpick quickly. In the chemical reaction that occurs between the antacid tablet and water produces carbon dioxide which was shown by the bubbles that put out the flame completely.

E) Based on your observation of the reaction that occurred when limewater was exposed to your breath, what gas did you exhale? Support your answer with your observations in Data Table 2.

When air is exhaled in limewater, it turns slightly cloudy ; which shows carbon dioxide gas; which is what we exhale when we breath out. The precipitate did not dissolve in the solution. CO2 reacted with Ca(OH)2 to produce CaCO3.