Chemistry Lab Report 2

04.04.12

Musa Çelik

Mustafa Çatal

Mustafa Sencer Aydın

9/A 219

Purpose

Our aim was to learn how Litmus paper works and how the process titration carries out.

Hypothesis: Litmus paper’s color will change to red if the matter is an acid, its color

will change to blue if the matter is a base. Concentration of an acid will be found by using

titration method.

Equipment and Materials

We had acetic acid, hydrogen chloride, sulphuric acid, ammonia, sodium hydroxide and some

other substances. In order to learn pH level of all these matters we used the Litmus paper. We

had also a beaker to make this process easy. In the other part of the experiment, we had a

measuring cylinder, a burette and indicator.

Procedure

Our object was to find whether a substance is an acid or base. First we put acids and bases

respectively to our beaker and learn their pH level by using Litmus paper. Later, we set up our

titration experiment. We put our base to beaker and our acid to the measuring cylinder. We

measured acid to the burette. We also add indicator to the acid. We started to put acid in

controlled manner. When the indicator became reddish we understood that the mixture is

neutralized.

What is Titration?

The volume of acid needed to neutralize an alkali was found by using an indicator, this

process is called titration. You can find the concentration of an acid using the same method.

The equipments needed for titration are:

-Beaker

-Burette

- Acid

-Base

-Funnel

-Indicator

Measurement

The pH level of CH3COOH is 2.4

The pH level of HCl is 1.0

The pH level of H2SO4 is 1.0

The pH level of NH3 is 11.6

The pH level of NaOH is 14.0

Titration in Process

We mixed our acid with 50 cm3 water. Then we add 50 cm3 acids to the burette and some

indicator. We started to pour it, when the amount of the acid decreased to 15 cm3. The mixture

was reddish.

It is necessary to give an example about titration measurement.

Step 1: Calculate the number of moles of sodium carbonate used.

1000 cm3 of 1 M solution contains 1 mole so 25 cm3 contains

251000

x1 mole or 0.025 mole.

Step 2: From the equation. find the molar ratio of acid to alkali.

2HCl (aq) + Na2CO3 (aq) 2NaCl(aq) + H2O (l)+ CO2(g)

The ratio is 2 moles of acid to 1 mole of alkali.

Step 3: Work out the number of moles of acid neutralized.

1 mole of alkali neutralizes 2 moles of acid so 0.025 mole of alkali neutralizes 2*0.025 moles

of acid.

0.05 moles of acids were neutralized.

Step 4: (25 cm3 = 0.025 dm3) Calculate the concentration of the acid.

concentration= number of moles

volume∈dm3¿

= 0.050.0278

¿ = 1.8 mol/dm3

So the concentration of HCl acid is 1.8 moles.

Conclusion

We learned that we can calculate concentration of acid or base by using titration. Also we

found that litmus paper changes its color according to the substance that affects the litmus

paper. It is clear that litmus paper turns to red with acids, turns blue with bases.