chem Describe how you would distinguish between the followin

4a)

Add dilute hydrochloric acid to both solutions.
Sodium carbonate solution:
A colourless gas will then be given out, which turns lime water milky.
Sodium hydroxide solution:
Heat is given out since neutralization.

b)

Dilute hydrochloric acid is a strong acid (Higher pH value (about 1)) but dilute ethanoic acid is a weak acid (Lower pH value (about 2-3)).

Method 1:

Reation with magnesium

HCl gives H2 gas at a faster rate.
CH3COOH gives at a slower rate.

Method 2:

Electrical conductivity

HCl - light bulb glows brighter
CH3COOH - Light bulb glows dimmer

a) Add dilute hydrochloric acid to both solutions.
Na2Co3 + 2HCl -----> 2NaCl + H2O + CO2
Colourless bubbles evolved which turns limewater milky.
NaOH + HCl -----> NaCl + H2O
No gas bubbles evolved.

b) Check for their electrical conductivities. HCl ionizes completely in water but CH3COOH only ionizes partly. HCl conducts electricity better then CH3COOH.
(You can check conductivities with a light bulb or ammeter.)

2007-02-20 23:46:36 補充：
Quote from Cecilia:"Dilute hydrochloric acid is a strong acid (Higher pH value (about 1)) but dilute ethanoic acid is a weak acid (Lower pH value (about 2-3))."pH 1 is a LOWER pH value than pH 2-3!!