Experiment 1: Analysis of unknown solution/liquid
Introduction:For this practical analysis you are given full instructions which you must carefully follow. It is up to
you to work safely and responsibly and to organise your time to ensure you complete the full practical.
You have three tests to carry out. At the end of the tests you must identify solutions/liquid A, B and C using your
observations.
You are provided with the following:
Magnesium ribbon, Mg
Flammable
Copper (II) oxide, CuO
Harmful
Copper (II) carbonate, CuCO3
Harmful
A
Irritant
B
Irritant
C
Irritant
The three unknown solutions/liquid, in no particular order are:

More concentrated hydrochloric acid, HCl (1.0 mol dm-3)

Dilute hydrochloric acid, HCl (0.1 mol dm-3)

Water
Test 1:
1. Add approximately 3cm3 of solutions A, B and C to three separate test tubes.
2. Put a piece of magnesium ribbon in each test tube.
3. Feel each test tube to judge whether there is a change in temperature.
4. Record your observations in the table below.
Test 2:
1. Add approximately 3cm3 of each solution to three separate test tubes.
2. Place 1 small spatula of copper (II) oxide (CuO) into each test tube.
3. Record your observations in the table below.
Test 3:
1. Add approximately 3cm3 of each solution to three separate test tubes.
2. Place 1 small spatula of copper (II) carbonate (CuCO3) into each test tube.
3. Record your observations in the table below.
Results:
Unknown
Solution
Test 1
Observations
Test 2
Test 3
A
B
C
[6]
Use the results from Test 1, Test 2 and Test 3 to identify the unknown solutions. Complete the following by adding
the correct letter (A, B or C) after each of the following:
More concentrated hydrochloric acid, HCl (1.0 mol dm-3)………………..
Dilute hydrochloric acid, HCl (0.1 mol dm-3)
………………..
Water
………………..
[2]
Explain how you knew which was the more concentrated acid.
…………………………………………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………………………………………….
…………………………………………………………………………………………………………………………………………………………….
[1]
Write a balanced equation for the reaction of magnesium with hydrochloric acid.
…………………………………………………………………………………………………………………………………………………………….
[1]
Total = 10 marks