Acid Reactions

Acid Reactions

Aim:

To test the effects of acids on some oxides, hydroxides, carbonates and hydrogen carbonates commonly found in rocks.

Equipment:

Reference: page 142, Experiment 22, Book: Exploring Chemistry

Procedure:

Reference: page 142, Experiment 22, Book: Exploring Chemistry

Observations and Results:

Section	Reactants	Observation	Products
1A	Hydrochloric Acid + Red Lithmic Paper	No Change
B	Hydrochloric Acid + Blue Lithmic Paper	Paper turned red
C	Sodium Hydroxide + Red Lithmic Paper	Paper turned blue
D	Sodium Hydroxide + Blue Lithmic Paper	Paper changed to light blue
E	Hydrochloric Acid + Litmus Solution	Turned Red
2A	Copper Oxide + Hydrochloric Acid	Bubble up Turned black	Copper chloride + Water
B	Ferric Oxide + Hydrochloric Acid	Turned yellowish Bubbled up Went thick Goes red	Ferric Chloride + Water
C	Iron Oxide + Hydrochloric Acid	Bubbled Up Went thick	Iron Chloride + Water
D	Aluminium Hydroxide + Hydrochloric Acid	Turn White Bubbles	Aluminium Chloride + Water
E	Calcium Hydroxide + Hydrochloric Acid	Turns white Bubbles	Calcium Chloride + Water
F	Lead Monoxide + Hydrochloric Acid	Turns yellow Bubbles Yellow substance turns solid	Lead Chloride + Water
3A	Calcium Hydroxide + Calcium Carbonate + Hydrochloric Acid	White solution Bubbles Made liquid white/cloudy	Calcium Chloride + Water + Carbon Dioxide
B	Calcium Hydroxide + Sodium Carbonate + Hydrochloric Acid	Bubbles Up White solution	Sodium Chloride + Water + Carbon Dioxide
C	Calcium Hydroxide + Calcium Carbonate + Acetic Acid	No Result	Calcium Acetate + Water + Carbon Dioxide

1.       CuO + 2HCl ==> CuCl₂ + H₂O

2.       Fe₂O₃ + 6HCl ==> 2FeCl₃ + 3H₂O

3.       FeO + 2HCl ==> FeCl₂ + H₂O

4.       Al(OH)₃ + 3HCl ==> AlCl₃ + 3H₂O

5.       Ca(OH)₂ + 2HCl ==> CaCl₂ + 2H₂O

6.       PbO + 2HCl ==> PbCl₂ + H₂O

7.       CaCO₃ + 2HCl ==> CaCl₂ + CO₂ + H₂O

8.       Na₂CO₃ + 2HCl ==> 2NaCl + CO₂ + H₂O

9.       CaCO₃ + 2CH₃COOH ==> Ca(CH₃COO)₂ + H₂O + CO₂

Sodium Hydroxide and hydrochloric acid make a salt which is sodium chloride and water. This is because the hydrochloric acid’s acidity is neutralised by the sodium hydroxide. Ammonia and hydrochloric acid makes ammonium chloride. An experiment on YouTube shows this reaction with a flask full of ammonia gas and places a cotton tip soaked in hydrochloric acid over it. This reaction creates a white smoke that comes off the cotton tip which is ammonium chloride.

If the solutions were not warmed up enough, the reaction would not have occurred. We can relate this back to Reaction Times, where for a reaction to occur the compounds must have enough kinetic energy. Also warming up the solution too much (what our group did), made the reaction time even faster making the liquid bubbling up very quickly.

Both experiments form the same products. This is because they are both strong acids (between 0 – 3 pH) reacting with a carbonate. This means that it will form a salt, water and carbon dioxide.

A normal rain has a pH level of 5.6 which is a weak acid. This is because the carbon dioxide in the atmosphere reacts with the water to form carbonic acid. Limestone is mainly made up of calcium carbonate. Calcium carbonate is a base that neutralises an acid. Therefore, an acidic rain which contains sulphuric and nitric acids in the rain water makes the rain much more acidic. Once this acidic rain lands on a limestone, the calcium carbonate reacts with the acidic rain water. Because calcium carbonate is a base and acidic rain is an acid (because of the mix of sulphuric and nitric acid in it), causes the limestone to dissolve to neutralise the acid.