I. Title : Indicators of Acid Solution and Alkaline Solution
II. Objectives:
• Experiment I: Learn the various types of natural materials which can be used as an indicator of acid and alkaline
• Experiment II: Determining the pH of the synthetic indicator
• Experiment I: Learn the various types of natural materials which can be used as an indicator of acid and alkaline
• Experiment II: Determining the pH of the synthetic indicator
Tujuan :
· Percobaan I : Mempelajari berbagai jenis bahan alami yang dapat digunakan sebagai indikator asam dan basa
· Percobaan II : Menentukan pH dari indikator sintetis
III. Base Theory:
The indicator is a compound that can provide different colors in a different atmosphere, for example, litmus is red in acid atmosphere, while under alkaline blue.
All around us, there are few natural dyes that can be used as an indicator, such as turmeric, extracts of colored flower petals, with the condition may change color in a different atmosphere.
With the indicators, we can determine a solution is acidic, alkaline, or neutral. With our universal indicator to determine the pH of a solution. Universal indicator is a mixture of several kinds of indicators that have been standardized color at pH 0-14. Therefore, by matching the color of universal indicator in a solution with the standard color, we can estimate the pH of the solution.
In the laboratory, there are several indicators such as phenolptalien (PP), brom thymol blue (BTB), methyl red (MM), methyl orange (MJ) with a specific route changes.
Gradual color change indicator. Red litmus indicator in the solution has a pH up to 5.5 and blue in a solution that has a pH greater than 8, whereas in the solution pH between 5.5 to 8, the color of litmus is a combination of the two colors, namely changed from red to purple then to blue. The limits of pH when the indicator changes color, we call the trajectory color change indicator, and with due regard to route pH indicator color change, we can estimate the price of the pH of a solution.
Some indicators along his route pH
The indicator is a compound that can provide different colors in a different atmosphere, for example, litmus is red in acid atmosphere, while under alkaline blue.
All around us, there are few natural dyes that can be used as an indicator, such as turmeric, extracts of colored flower petals, with the condition may change color in a different atmosphere.
With the indicators, we can determine a solution is acidic, alkaline, or neutral. With our universal indicator to determine the pH of a solution. Universal indicator is a mixture of several kinds of indicators that have been standardized color at pH 0-14. Therefore, by matching the color of universal indicator in a solution with the standard color, we can estimate the pH of the solution.
In the laboratory, there are several indicators such as phenolptalien (PP), brom thymol blue (BTB), methyl red (MM), methyl orange (MJ) with a specific route changes.
Gradual color change indicator. Red litmus indicator in the solution has a pH up to 5.5 and blue in a solution that has a pH greater than 8, whereas in the solution pH between 5.5 to 8, the color of litmus is a combination of the two colors, namely changed from red to purple then to blue. The limits of pH when the indicator changes color, we call the trajectory color change indicator, and with due regard to route pH indicator color change, we can estimate the price of the pH of a solution.
Some indicators along his route pH
Indicators | Colour | pH |
Phenolptalein | No colour - Red | 8,3 – 10,0 |
Brom timol biru | Yellow - Blue | 6,0 – 8,0 |
Metil Merah | Red - Yellow | 4,4 – 6,2 |
Metil Jingga | Red - Yellow | 3,1 – 4,4 |
Acid-base indicators mostly regarded as a weak acid with the equilibrium reaction as follows:
HIn(aq) <=> H+(aq) + In-(aq)
Hin color different from the color of In-. If the indicator was added acid or base, there will be a shift in equilibrium position indicator, so that the color indicator will change. The point of color change in the indicator occur if:
[HIn] = [In-]
So when the addition or reduction of acidity, there will be a shift in equilibrium which will also cause discoloration. Suppose the indicator litmus which when added to the concentration of H +, the equilibrium reaction will shift to the left or to the hin so litmus red, whereas if the concentration of H + reduced, or combined with basic compounds, then the equilibrium will shift to the right or to the In-, so that the litmus changes color to blue.
[HIn] = [In-]
So when the addition or reduction of acidity, there will be a shift in equilibrium which will also cause discoloration. Suppose the indicator litmus which when added to the concentration of H +, the equilibrium reaction will shift to the left or to the hin so litmus red, whereas if the concentration of H + reduced, or combined with basic compounds, then the equilibrium will shift to the right or to the In-, so that the litmus changes color to blue.
Kajian Teori :
Indikator adalah suatu senyawa yang dapat memberikan warna berbeda dalam suasana yang berbeda, misalnya lakmus yang dalam suasana asam berwarna merah sedangkan dalam suasana basa berwarna biru.
Di sekitar kita, terdapat beberapa zat warna alami yang dapat digunakan sebagai indikator, seperti kunyit, ekstrak daun mahkota bunga berwarna, dengan syarat dapat mengalami perubahan warna dalam suasana yang berbeda.
Dengan indikator, kita dapat menentukan suatu larutan bersifat asam, basa, atau netral. Dengan indikator universal kita dapat menentukan pH suatu larutan. Indikator universal adalah campuran dari beberapa macam indikator yang telah distandarisasi warnanya pada pH 0-14. Oleh karena itu, dengan mencocokkan warna indikator universal dalam suatu larutan dengan warna standart, kita dapat memperkirakan pH larutan tersebut.
Di laboratorium, terdapat beberapa indikator misalnya phenolptalien (PP), brom timol biru (BTB), metil merah (MM), metil jingga (MJ) dengan trayek perubahan tertentu.
Warna indikator berubah secara gradual. Indikator lakmus berwarna merah dalam larutan yang memiliki pH sampai dengan 5,5 dan berwarna biru dalam larutan yang memiliki pH lebih dari 8, sedangkan dalam larutan yang pH-nya antara 5,5-8, warna lakmus adalah kombinasi dari kedua warna tersebut, yaitu berubah dari merah menjadi ungu kemudian menjadi biru. Batas-batas pH ketika indikator mengalami perubahan warna, kita sebut dengan trayek perubahan warna indikator, dan dengan memperhatikan trayek pH perubahan warna indikator tersebut, kita dapat memperkirakan harga pH suatu larutan.
Beberapa indikator beserta trayek pH-nya
Indikator | Warna | pH |
Phenolptalein | Tak Berwarna – Merah | 8,3 – 10,0 |
Brom timol biru | Kuning – Biru | 6,0 – 8,0 |
Metil Merah | Merah – Kuning | 4,4 – 6,2 |
Metil Jingga | Merah – Kuning | 3,1 – 4,4 |
Indikator asam basa kebanyakan dianggap sebagai asam lemah dengan reaksi kesetimbangan sebagai berikut:
HIn(aq) <=> H+(aq) + In-(aq)
Warna HIn berbeda dengan warna In-. Jika indikator ini ditambahkan asam atau basa , maka akan terjadi pergeseran letak kesetimbangan indikator, sehingga warna indikator akan berubah. Titik perubahan warna pada indikator terjadi jika:
[HIn] = [In-]
Jadi ketika terjadi penambahan atau pengurangan keasaman, maka akan terjadi pergeseran kesetimbangan yang juga akan menyebabkan perubahan warna. Misalkan pada indikator lakmus yang apabila ditambah konsentrasi H+, kesetimbangan reaksinya akan bergeser ke kiri atau ke HIn sehingga lakmus berwarna merah, sedangkan apabila konsentrasi H+ dikurangi, atau ditambah dengan senyawa basa, maka kesetimbangan akan bergeser ke kanan atau ke In-, sehingga lakmus berubah warna menjadi biru.
IV. Tools and materials:
• Experiment I
1. Pipette
2. Drop Plates
3. Extracts of hibiscus crown
4. Turmeric extract
5. Coconut milk
6. Suji leaf extract
7. Carrot extract
8. Vinegar
9. Water Soap
10. Water
• Experiment II
1. Pipette
2. Plate drops
3. 4 test tubes
4. Methyl red
5. Methyl orange
6. Brom thymol blue
7. Phenolptalein
8. Salt A
9. Salt B
10. Salt C
11. Salt D
12. Water
• Experiment I
1. Pipette
2. Drop Plates
3. Extracts of hibiscus crown
4. Turmeric extract
5. Coconut milk
6. Suji leaf extract
7. Carrot extract
8. Vinegar
9. Water Soap
10. Water
• Experiment II
1. Pipette
2. Plate drops
3. 4 test tubes
4. Methyl red
5. Methyl orange
6. Brom thymol blue
7. Phenolptalein
8. Salt A
9. Salt B
10. Salt C
11. Salt D
12. Water
Alat dan Bahan :
Percobaan I
1. Pipet
2. Pelat Tetes
3. Ekstrak mahkota bunga sepatu
4. Ekstrak kunyit
5. Santan
6. Ekstrak daun suji
7. Ekstrak wortel
8. Cuka
9. Air Sabun
10. Air
Percobaan II1. Pipet
2. Pelat tetes
3. 4 tabung reaksi
4. Metil merah
5. Metil jingga
6. Brom timol biru
7. Phenolptalein
8. Garam A
9. Garam B
10. Garam C
11. Garam D
12. Air
V. Experiment Steps
• Experiment I
1. Take extract hibiscus crown
2. Place each one drops into the drip plate
3. Add 1 drop of vinegar into the first plate drops
4. Observe and record the color changes that occur
5. Squirt soapy water into the plate drops into two
6. Observe and record the color changes that occur
7. Perform experiments to other indicators with the same steps
• Experiment II
1. Enter the salt in a test tube A to I
2. Mix with water and stir
3. Add 1 drop of solution A to each plate drops by 4 plates
4. Add 2 drops of indicator solution on each plate drops, namely:
5. Note the color changes that occur
6. Perform the same experiment on a solution of B, C, and D
• Experiment I
1. Take extract hibiscus crown
2. Place each one drops into the drip plate
3. Add 1 drop of vinegar into the first plate drops
4. Observe and record the color changes that occur
5. Squirt soapy water into the plate drops into two
6. Observe and record the color changes that occur
7. Perform experiments to other indicators with the same steps
• Experiment II
1. Enter the salt in a test tube A to I
2. Mix with water and stir
3. Add 1 drop of solution A to each plate drops by 4 plates
4. Add 2 drops of indicator solution on each plate drops, namely:
5. Note the color changes that occur
6. Perform the same experiment on a solution of B, C, and D
V. Langkah Percobaan
Percobaan I
1. Ambil ekstrak mahkota bunga sepatu
2. Tempatkan masing-masing satu tetes ke dalam pelat tetes
3. Tambahkan 1 tetes larutan cuka ke dalam pelat tetes pertama
4. Amati dan catat perubahan warna yang terjadi
5. Teteskan air sabun ke dalam pelat tetes ke dua
6. Amati dan catat perubahan warna yang terjadi
7. Lakukan percobaan untuk indikator lainnya dengan langkah yang sama
Percobaan II
1. Masukkan garam A ke dalam tabung reaksi I
2. Campurkan dengan air dan aduk
3. Tambahkan 1 tetes larutan A untuk masing-masing pelat tetes sebanyak 4 pelat
4. Tambahkan 2 tetes larutan indikator pada setiap pelat tetes, yaitu:
5. Catat perubahan warna yang terjadi
6. Lakukan percobaan yang sama terhadap larutan B, C, dan D
VI. Observe Data
Percobaan I
Bahan yang diuji | Warna awal | Warna setelah ditetesi cuka | Warna setelah ditetesi air sabun |
Ekstrak bunga sepatu | Ungu | Merah muda | Hijau tua |
Ekstrak wortel | Jingga | Jingga | Jingga |
Ekstrak daun suji | Hijau | Hijau | Hijau |
Ekstrak kunyit | Kuning | Kuning | Merah |
Santan | Putih | Putih | Putih |
Percobaan II
Indikator | Larutan A | Larutan B | Larutan C | Larutan D |
Warna indikator | Warna indikator | Warna indikator | Warna indikator | |
Metil merah | Kuning | Kuning | Kuning | Kuning |
Metil jingga | Kuning | Kuning | Kuning | Kuning |
Brom timol biru | Biru | Hijau | Kuning | Kuning |
Phenolptalein | Merah muda | Tak berwarna | Tak berwarna | Tak berwarna |
VII. Data Analysis
• Experiment I
This experiment aims to determine which types of natural materials which can be used as an indicator of acid and alkaline. By considering the equation
• Experiment I
This experiment aims to determine which types of natural materials which can be used as an indicator of acid and alkaline. By considering the equation
HIn(aq) <=> H+(aq) + In-(aq)
we can determine that the material can be an indicator of acid-base or not, ie if the plus or minus ions H +, a solution of the material that will change color. That's because the shift of equilibrium to the left (if coupled ion H +) and right (if the ion H + is reduced or increased ion OH-). Based on data from the experiment results above, it can be concluded that the natural ingredients that can be used as acid-base indicator is a hibiscus flower extract and turmeric extract, because once poured a solution of vinegar (acid) and soapy water (base), the second solution of natural materials that have discoloration. Meanwhile, carrot extract, suji leaf extract, and coconut milk can not be used as acid-base indicator for the third solution of natural ingredients that do not change color even after drops of vinegar and soapy water. Consider again equation
HIn(aq) <=> H+(aq) + In-(aq)
In the experiment by using extracts of carrots, leaf extract suji, and coconut milk, the concentration of ions in-remains higher than the concentration of Hin, although it has been added or reduced H + ions it, so that equilibrium is still shifted to the left and the colors that looked too is the first color (color beginning of the material being tested).
• Experiment II
In this experiment, the goal is to estimate the pH of the synthetic indicator, namely salt named A, B, C and D. In order to estimate the pH of some indicators, we must consider the table
In the experiment by using extracts of carrots, leaf extract suji, and coconut milk, the concentration of ions in-remains higher than the concentration of Hin, although it has been added or reduced H + ions it, so that equilibrium is still shifted to the left and the colors that looked too is the first color (color beginning of the material being tested).
• Experiment II
In this experiment, the goal is to estimate the pH of the synthetic indicator, namely salt named A, B, C and D. In order to estimate the pH of some indicators, we must consider the table
Indikator | Warna | pH |
Phenolptalein | No color - red from | 8,3 – 10,0 |
Brom Timol Biru | Yellow - Blue | 6,0 – 8,0 |
Metil Merah | Red - Yellow | 4,4 – 6,2 |
Metil Jingga | Red - Yellow | 3,1 – 4,4 |
By using these tables, we can estimate the pH of salts dissolved in water in the experiment this time, namely:
-- pH o A: more than 8.3
-- pH o B: more than 6.2 and less than 8.3
-- pH o C: more than 4.4 and less than 6.0
-- pH o D: more than 4.4 and less than 6.0
Results were obtained from the table analysis estimates the following pH:
-- pH o A: more than 8.3
-- pH o B: more than 6.2 and less than 8.3
-- pH o C: more than 4.4 and less than 6.0
-- pH o D: more than 4.4 and less than 6.0
Results were obtained from the table analysis estimates the following pH:
Indikator | Larutan A | Larutan B | Larutan C | Larutan D |
Perkiraan pH | Perkiraan pH | Perkiraan pH | Perkiraan pH | |
Metil merah | > 6,2 | > 6,3 | > 6,2 | > 6,2 |
Metil jingga | > 4,4 | > 4,4 | > 4,4 | > 4,4 |
Brom timol biru | > 8,0 | 6 – 8 | < 6,0 | < 6,0 |
Phenolptalein | > 8,3 | < 8,3 | < 8,3 | < 8,3 |
From the experiment results, it can be seen that there indkator showing the results of which always remains, even if tested with different synthetic materials. This is because [Hin] is always lower than or not equal to [In-] so that the equilibrium shifts and changes color. So then, these indicators do not need to be used again for further examination, including in the calculation or estimation of pH.
VII. Analisa Data
· Percobaan I
Percobaan ini bertujuan untuk mengetahui jenis bahan alami yang mana yang dapat digunakan sebagai indikator asam dan basa. Dengan memperhatikan persamaan
HIn(aq) <=> H+(aq) + In-(aq)
kita dapat menentukan bahan itu dapat dijadikan indikator asam basa atau tidak, yakni jika dengan ditambah atau dikurangi ion H+, larutan bahan itu akan berubah warna. Hal itu dikarenakan terjadinya pergeseran kesetimbangan ke kiri (jika ditambah ion H+) dan ke kanan (jika ion H+ berkurang atau bertambahnya ion OH-). Berdasarkan data hasil percobaan di atas, dapat disimpulkan bahwa bahan alami yang dapat dijadikan indikator asam basa adalah ekstrak bunga sepatu dan ekstrak kunyit, karena setelah ditetesi larutan cuka (asam) dan air sabun (basa), larutan kedua bahan alami itu mengalami perubahan warna. Sedangkan ekstrak wortel, ekstrak daun suji, dan santan tidak dapat dijadikan indikator asam basa karena larutan ketiga bahan alami itu tidak mengalami perubahan warna walaupun telah ditetesi cuka maupun air sabun. Coba perhatikan lagi persamaan
HIn(aq) <=> H+(aq) + In-(aq)
Pada percobaan dengan menggunakan ekstrak wortel,dsgsdg ekstrak daun suji, dan santan, konsentrasi ion In- tetap lebih tinggi daripada konsentrasi HIn, walaupun telah ditambahkan ataupun dikurangi ion H+ nya, sehingga kesetimbangan tetap bergeser ke kiri dan warna yang tampak juga adalah warna pertama (warna awal dari bahan yang diuji).
· Percobaan II
Pada percobaan ini, tujuannya adalah memperkirakan pH dari indikator sintetis, yakni yang diberi nama garam A, B, C, dan D. Untuk dapat memperkirakan pH beberapa indikator itu, kita harus memperhatikan tabel
Indikator | Warna | pH |
Phenolptalein | Tak berwarna – merah | 8,3 – 10,0 |
Brom Timol Biru | Kunig – Biru | 6,0 – 8,0 |
Metil Merah | Merah – Kuning | 4,4 – 6,2 |
Metil Jingga | Merah – Kuning | 3,1 – 4,4 |
Dengan menggunakan tabel tersebut, kita dapat memperkirakan pH dari garam-garam yang dilarutkan dengan air pada percobaan kali ini, yakni:
o pH larutan A : lebih dari 8,3
o pH larutan B : lebih dari 6,2 dan kurang dari 8,3
o pH larutan C : lebih dari 4,4 dan kurang dari 6,0
o pH larutan D : lebih dari 4,4 dan kurang dari 6,0
Hasil analisa itu diperoleh dari tabel perkiraan pH berikut ini:
Indikator | Larutan A | Larutan B | Larutan C | Larutan D |
Perkiraan pH | Perkiraan pH | Perkiraan pH | Perkiraan pH | |
Metil merah | > 6,2 | > 6,3 | > 6,2 | > 6,2 |
Metil jingga | > 4,4 | > 4,4 | > 4,4 | > 4,4 |
Brom timol biru | > 8,0 | 6 – 8 | < 6,0 | < 6,0 |
Phenolptalein | > 8,3 | < 8,3 | < 8,3 | < 8,3 |
Dari hasil percobaan, dapat dilihat bahwa terdapat indkator yang menunjukkan hasil yang selalu tetap, walaupun diuji dengan bahan sintetis yang berbeda. Hal itu disebabkan [HIn] selalu lebih rendah atau tidak sama dengan [In-] sehingga tidak terjadi pergeseran kesetimbangan dan perubahan warna. Jadi kalau begitu, indikator tersebut tidak perlu dipakai lagi untuk pemeriksaan lebih lanjut, termasuk dalam perhitungan atau perkiraan pH.
VIII. Conclusion
a. Not all natural ingredients can be used as acid-base indicator. Of the 5 natural ingredients that have been tested, the results were obtained:
a. Hibiscus extract and turmeric extract color change after the drops with a solution of vinegar and soapy water, so it can be said that these two natural ingredients can be used as acid-base indicator.
b. Extracts of carrot, suji leaf extract, and coconut milk has not changed even though the color has been poured with vinegar (as the acid compound) and soapy water (as a base compound), so that the three natural ingredients that can not be used as acid-base indicator.
b. pH of a solution can be estimated by adding the acid-base indicator into it, so can be estimated according to the pH color change indicator.
c. Of the four salts that have been tested, and after adjusting the pH change of color on the indicator, obtained by approximate pH of each:
a. pH A: more than 8.3
b. B pH: between 6.2 and 8.3
c. C pH: between 4.4 and 6.0
d. D pH: between 4.4 and 6.0
d. The shift of equilibrium does not always occur on the addition or reduction reactions of acids and bases on indicators, which is caused by the ion concentration was not with him hin with In-or In-ion concentration is always higher than the ion Hin so that equilibrium is always shifted to the left which means that the indicator will always show initial color (do not change color)
a. Not all natural ingredients can be used as acid-base indicator. Of the 5 natural ingredients that have been tested, the results were obtained:
a. Hibiscus extract and turmeric extract color change after the drops with a solution of vinegar and soapy water, so it can be said that these two natural ingredients can be used as acid-base indicator.
b. Extracts of carrot, suji leaf extract, and coconut milk has not changed even though the color has been poured with vinegar (as the acid compound) and soapy water (as a base compound), so that the three natural ingredients that can not be used as acid-base indicator.
b. pH of a solution can be estimated by adding the acid-base indicator into it, so can be estimated according to the pH color change indicator.
c. Of the four salts that have been tested, and after adjusting the pH change of color on the indicator, obtained by approximate pH of each:
a. pH A: more than 8.3
b. B pH: between 6.2 and 8.3
c. C pH: between 4.4 and 6.0
d. D pH: between 4.4 and 6.0
d. The shift of equilibrium does not always occur on the addition or reduction reactions of acids and bases on indicators, which is caused by the ion concentration was not with him hin with In-or In-ion concentration is always higher than the ion Hin so that equilibrium is always shifted to the left which means that the indicator will always show initial color (do not change color)
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