CHEMISTRY
REPORT
“
ACID-BASE EXPERIMENT ”
Basic
Theory
The indicator is a compound that can provide different colors in a different
atmosphere.
All around us, there are few natural dyes that can be used as an
indicator, such as bugenvile, carrot, extracts of colored flower petals,
hibiscus crown, or purple cabbage with the condition may change color in a
different atmosphere.
With the indicators, we can determine a solution whether that solution
is acid, alkali, or neutral. We also have the universal indicator to determine
the pH of a solution. Universal indicator is a mixture of several kinds of
indicators that have been standardized. It has a pH range from 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. For the result that shows 7, it means
that the solution is neutral. If the result is lower than 7, it means that the
solution is acid. For more than 7, it shows that the solution is alkali.
In the laboratory, there are several indicators such as phenolptalien
(PP), bromthymol blue (BTB), methyl red (MM), methyl orange (MJ) with a
specific route changes. The common indicator that use is litmus. There are two
litmus named red litmus and blue litmus.
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. For the solution that has pH from 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
|
COLOR
|
pH
|
Phenolptalein
|
No colour- Red
|
8,3 – 10,0
|
Brom timol biru
|
Yellow – Blue
|
6,0 – 8,0
|
Red metal
|
Red – Yellow
|
4,4 – 6,2
|
Orange metal
|
Red – Yellow
|
3,1 – 4,4
|
According to Arrhenius Theory, acid
and base is defined based on the release of H+ and OH- ions
from base is later is understood as an equilibrium reaction. The concentration
of the H+ is stated in the form of a pH value. The Arrhenius theory
is generally used to explain acid and base reaction in water solvent.
The equilibrium reaction can
represent as follows:
HIn(aq) <=> H+ (aq) + In-(aq)
HIn color is different from the color of In- ion. If the
indicator was added by 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 occurs if:
[HIn] = [In-]
So when the addition or reduction of acidity, there will be a shifted 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.
There
is a little difference for neutral indicator. Like have mentioned before,
neutral indicator is the indicator that found around us. It means that we can
take it and use it directly. But, a neutral indicator has many disadvantages.
One of the disadvantages is it can’t determine the exact value for the pH. It
just can show whether a solution is either acid or base, or even neutral. Each
natural indicator has its own pattern. One natural indicator may be changed
into green if we added an acid solution onto it or maybe the other color.
ACID-BASE
EXPERIMENT
Title:
Indicators of Acid Solution and Alkaline Solution
I. Objectives:
• Experiment I: Learn the various types of
natural materials which can be used as an indicator of acid and alkaline
II. Tools and materials:
• Tools
1. Pipette
2. Drop Plates
3. Graduated Beaker
4. Test tube
5. Spatula
6. Vestal and portal
·
Materials
1. Extracts of hibiscus crown
2. Bugenvil extract
3. Carrot extract
4. Purple cabbage extract
5. “ Kemerakan” extract
6. Vinegar
7. Lime water
8. Water
III. Experiment Steps
1. Make extract hibiscus crown with
vestal and portal
2. Take extract hibiscus crown
3. Place each one drops into the drip
plate
4. Add 1 drop of vinegar into the first
plate drops
5. Observe and record the color changes
that occur
6. Squirt lime water into the plate
drops into two
7. Observe and record the color changes
that occur
8. Perform experiments to other
indicators with the same step
IV. OBSERVE
DATA
No.
|
Material
|
Initial Color
|
Color after dropped Vinegar
|
Color after dropped lime water
|
1.
2.
3.
4.
5.
|
Extracts of hibiscus crown
Bugenvile extract
Carrot extract
“Kemerakan” extract
Purple cabbage
extract
|
Purple
Red
Orange
Orange
Purple
|
Red
Red
Orange
Light orange
Pink
|
Green
Red orange
Old orange
Old green
Blue
|
V. Data Analysis
This experiment aims is 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, i.e. 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 crown extract and purple cabbage
extract, because once poured a solution of vinegar (acid) and lime water
(base), the second solution of natural materials that have discoloration.
Meanwhile, carrot extract, bugenvile extract and kemerakan extract can’t be
used as acid-base indicator. It happened because the third solution of natural
ingredients do not change color even after drops of vinegar or lime water.
Consider again equation
HIn(aq) <=>
H+(aq) + In-(aq)
In the experiment by using extracts of carrot
extract, bugenvile extract and kemerakan extract, the concentration of ions In-remains
higher than the concentration of HIn, although it has been added or reduced H+
ions from it, the equilibrium is still shifted to the left and the colors that
looked too is the first color (color beginning of the material being tested).
From the experiment results, it can
be seen that there indicator 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.
VI. 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:
b) Hibiscus extract and purple cabbage
color change after the drops with a solution of vinegar and lime water, so it
can be said that these two natural ingredients can be used as acid-base
indicator.
c) carrot extract, bugenvile extract and
kemerakan extract has not changed even though the color has been poured with
vinegar (as the acid compound) and lime water (as a base compound), so that the
three natural ingredients that can’t be used as acid-base indicator.
d) 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.
e) 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-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)
TESTING pH USING
THE INDICATOR UNIVERSAL
I.
Objectives
·
To know more about laboratory equipment, know
name of it and also can use it when we want to doing experiment, so we hope we
haven’t got confuse about laboratory equipment.
·
Know characteristic some of water in general
environment like acid or base and also know ph some of water so if in the
future we want to doing experiment we not confuse to choose some water that
have characteristic acid or base.
·
To know more accurate about ph that contain in
the some of water.
·
Learn to be patient when we get experiment, so
the result will be better.
II.
TOOLS AND MATERIAL
·
Tools:
1.
Plate tetes
2.
Pipet tetes
3.
Botol
4.
Graduated Glass
5.
Universal Indicator
6.
Litmus
·
Material:
1.
Sugar
Solution
2.
Soap Solution
3.
Detergen
Solution
4.
Water tank
5.
Gutter water
6.
Water
7.
River Water
8.
Star fruit
water
9.
Water in Air
Sanih
10.
Lemon water
11.
Water pool
12.
Rain Water
III.
WORK STEP
1.
Prepare some beaker glass or bottle (if no there
are beaker glass) as the place of some water.
2.
Search some water that we want to use in
experiment and try to find original water for example if you want to search
rain water you must waiting until water rain falling.
3.
If you have found it. Put some water in the
ideal place, give cover like the name in each of the bottle, so when we looking
for the label we not get confuse.
4.
Take some universal indicator which will we use
to check ph in each of the water, so we will know ph there are in the water.
5.
6.
Prepare some dropping pipette (that function is
to move each kind of water to the so we will easy to check it).
7.
Remember if you just have one dropping pipette
you must wash it after you used (the purpose is when we doing experiment there
are no contraction or mixture between the water).
8.
Doing experiment
with the ways
·
Put 1 paper universal indicator in to the bottle
and doing repeat to the other bottle until all kind of water filled by
universal indicator paper.
·
And then waiting until universal indicator paper
get to dry.
·
And the last check the color, using the color
which it have determine in the universal indicator or with the color universal
indicator.
9.
Write down the result of experiment on to the
book
IV.
WORK RESULT
NO
|
Material
|
pH
|
1
|
Sugar
Solution
|
7
|
2
|
Soap
Solution
|
8
|
3
|
Detergen
Solution
|
11
|
4
|
Tank water
|
7
|
5
|
Gutter
water
|
7
|
6
|
Water
|
7
|
7
|
River Water
|
6
|
8
|
Star fruit
water
|
2
|
9
|
Water in Air
Sanih
|
7
|
10
|
Lemon water
|
4
|
11
|
Pool water
|
5
|
12
|
Rain water
|
6
|
V.
PROBLEM
·
Difficult to find original water like rain water
that because the weather is dry so to find it so difficult.
·
Limited with laboratory equipment so to doing
experiment is little bit difficult
·
Difficult to determine the color blue, dark blue
and whatever.
VI.
CONCLUSION
f) Universal Indicator can be used as
acid-base indicator because that can divide the solution in specific pH.
g) Star fruit, Lemon water, river water,
pool water and rain water is example of acid because their pH is under 7.
h) Soap solution, detergen solution are
example of base because their pH is more than 7.
i)
Sugar
water, gutter watter, tank water and water in air sanih are kind of neutral
solution because their pH is 7.
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