Laporan praktikum kimia "asam dan basa"

Report 1

The pH Solution of Acid and Base

I.             Purpose

To measure the pH of some solution of strong and week acid / base whose concentration is the same using universal indicator

II.            Basic Theory                                                                                                            

·         According to Arrhenus,acid is a substance that releases H⁺ ions in water, while Base is a substance that releases OH ions in water.

·         According to Bransted Lowry acid is gives proton, while Base is accepts protons.

·         According Lewis, acid is a pair of electrons acceptor, while Base is  a pair of electrons electrons donor.

III.           Tools and Materials

Pasteur pipette                                 (1 pcs)

Volume pipette                                 (1 pcs)

Chemical glass                                (4 pcs)

Universal indicator paper               (3 pcs)

Water                                                  (as needed)

Funnel shaped                                 (1 pcs)

Measure gourd                                 (1 pcs)

NH₃ solution                                     (50 ml)

IV.          Procedure

1, prepare three clean and dry chemical glass.

2. give each glass a label by number 1,2, and 3.

3. add 5 ml of 0,1 M NH₃ solution into chemical glass 1.

4. make NH₃ solution with the concentration of 0,01 M and 0,001 M by dilution.

5. add 5 ml NH₃ solution into chemical glass 2 and 5 ml NH₃ solution into   chemical glass 3.

6. measure the pH of the three solutions using universal indicator paper.

7. repeat procedur 1 to 6 using CH₃COOH, NaOH, NH₃, HCl, NaCl.

Calculation

M.V = M_1. V₁

12. V  = 1 . 50

      V  = 4,2 X 2 = 8,4

M₁.V₂ = M_3. V₃

1 . V₂ = 0,1 . 50

      V₂ = 5

M₃.V₄ = M_5. V₅

0,1. V₄ = 0,01 . 50

      V₄= 5

M₅.V₆ = M_7. V₇

0,01. V₆ = 0,001 . 50

      V₆ = 5

V.           Result Experiment

Glass no.	Concentration of acid/base (M)	pH Solution
		HCl	CH3COOH	NaOH	NH3	NaCl	HCl
1	0,1	1	3	13	9	7	-
2	0,01	2	3,5	12	8	7	-
3	0,001	3	4	11	7,5	7	-
4	0,0001	-	-	-	-	-	4
5	0,00001	-	-	-	-	-	5
6	0,000001	-	-	-	-	-	6

VI.          Question

1.    What are the pH differences for acidic solution and base solution?

2.    What is the influence of the dilution to the pH of solution of strong acid and base?

3.    What is the influence of dilution to the pH of solution of weak acid and base?

Answer:

1.    The pH of acidic solution are less than 7

The pH of base solution more than 7

2.    When the strong acid dilution with water so the pH is increase because the concentration is decrease, and when the strong base diluted with water the pH is decrease because the concentration of solution is decrease.

3.    When the weak acid diluted with water, the pH is increase because the concentration of solution is decrease. And when then weak base diluted with water the pH is decrease because  the concentration of solution is decrease.

VII.        Conclusion

1.    The pH of solution is inversely proportional to the acid strength. It means that the more concentrated the solution of acid, the smaller the pH value is.

2.    The pH is proportional to the base strength. It means that more concentrated the solution of base, bigger the pH value.

VIII.       Photos

Gambar 1.1 Pengenceran NH₃

Gambar 1.2 mengukur pH larutan menggunakan kertas indicator

Gambar 1.3 hasil pengukuran pH

IX.          Bibliography

Utami, Budi, Agung Nugroho Catur Saputro, Lina Mahardiani, Sri Yamtinah, Bakti     Mulyani.  2006. Simpati. Surakarta:Grahadi.

Sudarmo, Unggul. 2004. Kimia. Surakarta:Seri Made Simple.

Susilowati, Endang. 2009. Chemistry. Solo:Tiga Serangkai.