Experiments on properties of acids and bases are one of the most vital topics in chemistry. It is discussed that the sour chemicals usually turns blue litmus into red are called acids. In a similar fashion, bases that are bitter tasting convert red litmus into blue. And acids and bases on reaction with one another give salt and water. This indicates neutralizing i.e, both the base and acid neutralize into the pH of water.
These facts will only remain assumptions if not tested and experimented with. Therefore, this article will consist of Experiments on Properties of Acids and Bases. There will be three experiments each with HCl as the acid and NaOH as the base. These will be tested with compounds like; a litmus solution (blue/red), zinc metal, and Sodium carbonate (solid).
There are various materials that are required for conducting the Experiments on Properties of Acids and Bases. These are
Matchbox,
Dropper,
Test Tube stand,
Test tube holder
Burner
Thistle funnel
Litmus Solution or Paper (Both Red and Blue)
Test Tubes
Flat Bottom flask
Zinc Granules
Lime Water (Freshly Made)
Breaker
Sodium Carbonate (Solid)
Dilute NaOH
Dilute HCl
Figure 1: List of required chemicals and materials
(Nefronus, Zinc sample, CC0 1.0) (Ondřej Mangl, Uhličitan sodný, marked as public domain, more details on Wikimedia Commons) (Walkerma at en.wikipedia, Hydrochloric acid 04, marked as public domain, more details on Wikimedia Commons) (Ondřej Mangl, Hydroxid sodný, marked as public domain, more details on Wikimedia Commons) (Deamit, Одредување рН на примерок вода со Лакмусова хартија, CC BY 4.0)
Figure 2: Common mineral acids and acetic acid
The compounds that when dissolved in water, result in yielding positively charged hydronium ions are termed as acids.
Eg. - $\mathrm{HNO_3}$ releases $\mathrm{NO_3^{-}}$ and $\mathrm{H^+}$ ions just like HCl releases $\mathrm{H^+}$ and $\mathrm{Cl^-}$ ions.
Take two test tubes and place them on the stand for test tubes.
Now, label the two test tubes as 1 and 2.
Take the test tube 1 and fill in 5ml of the blue litmus solution.
Now pour 5 ml of red litmus solution in test tube 2.
Now, take HCl in a dropper and fill equal amounts in both test tube 1 and 2.
Look closely for the colour in the test tubes to change.
Figure 3: Litmus test
Deamit, Одредување рН на примерок вода со Лакмусова хартија, CC BY 4.0
Take a flat bottomed flask and add in Sodium Carbonate (1 gram) and a little distilled water.
Now take a cork (dry double bore). This cork should fit a thistle funnel. Also, a delivery tube should be fitted to it.
Now, use the dry double bore cork to close Flat Flask's mouth. Later add HCl gas (2ml).
The gas released is odorless and colourless. This gas then passes through the lime water and delivery tube.
On passing through the lime water, the lime water starts appearing milky.
The reaction involved in this experiment is:
$$\mathrm{HCl + Na_2CO_3\:\rightarrow\:2NaCl+H_20(liquid)+CO_2(gas)}$$
Figure 4: Action of Sodium Carbonate on HCl acid
Take a test tube (clean and dry) and put in it, Zinc granules.
Pour HCl (liquid) into the test tube and let the Zinc granules be submerged in it.
Now tilt the test tube a little and fix it with a cork properly.
Fix a Bunsen burner on the test tube and then light it.
Now close the test tube's mouth tightly. This should ensure that no vapours escape.
After leaving the solution for 2-3 minutes, it'll burn sounding robust and release a gas that's odourless and colourless.
Now, if you burn a matchstick in front of the test tube's mouth, a flame that's pale blue is seen followed by pop sound.
Below is the reaction involved in the above experiment:
$$\mathrm{Zn + 2HCl\:\rightarrow\:ZnCl_2+H_2\uparrow}$$
Figure 5: Action of Zn on HCl acid
Figure 6: Strong and weak bases (colors are used for distinction from one another not by any scientific mean)
The compounds that when dissolved in water, result in yielding negatively charged hydroxide ions are termed as bases.
Eg- NaOH releases Na+ and OH- ions.
Take two test tubes and place them on the stand for test tubes.
Now, label the two test tubes as 1 and 2.
Take the test tube 1 and fill in 5ml of the red litmus solution.
Now pour 5 ml of red litmus solution in test tube 2.
Now, take NaOH in a dropper and fill equal amounts in both test tube 1 and 2.
Look closely for the colour in the test tubes to change.
Take a flat bottomed flask and add in Sodium Carbonate (1 gram) and a little distilled water.
Now take a cork (dry double bore). This cork should fit a thistle funnel. Also, a delivery tube should be fitted to it.
Now, use the dry double bore cork to close Flat Flask's mouth. Later add dil NaOH (liquid).
There will be no changes i.e, no reaction occurs.
Take a test tube (clean and dry) and put in it, Zinc granules.
Pour NaOH (liquid) into the test tube and let the Zinc granules be submerged in it.
Now tilt the test tube a little and fix it with a cork properly.
Fix a Bunsen burner on the test tube and then light it.
Now close the test tube's mouth tightly. This should ensure that no vapours escape.
After leaving the solution for 2-3 minutes, it'll burn sounding robust and release a gas that's odourless and colourless.
Now, if you burn a matchstick in front of the test tube's mouth, a flame that's pale blue is seen followed by pop sound.
Below is the reaction involved in the above experiment −
$$\mathrm{2NaOH + Zn\:\rightarrow\:Na_2ZnO_2 +H_2\uparrow}$$
Figure 7: Action of Zn on NaOH
Because hydrogen produced in large amounts results in explosion then you should ensure taking small quantities of reactants (NaOH, HCl, Zn).
Use a fine jet for hydrogen burning.
Only after your apparatus is carefully made airtight, you should add HCl to Sodium Carbonate.
Handling NaOH and HCl like chemicals should be done carefully because they can cause injuries.
| Experiment | Acids | Bases |
|---|---|---|
| Experiment 1: Litmus Test | The blue litmus solution turns into red when reacted with Hydrochloric Acid. | The red litmus solution turns into blue when reacted with NaOH. |
| Experiment 2: Sodium Carbonate (Solid) | $\mathrm{CO_2}$ is released on reaction of HCl with sodium carbonate. | No reaction is observed on reaction of NaOH with sodium carbonate. |
| Experiment 3: Zinc | $\mathrm{ZnCl_2}$ and $\mathrm{H_2}$ gas are the products as a result of the reaction between HCl and Zinc. | Sodium Zincate and $\mathrm{H_2}$ gas are the products as a result of the reaction between NaOH and Zinc. |
On an experiment of Hydrochloric Acid with a blue litmus solution, the solution turns red. Similarly, in reaction with Sodium Carbonate, $\mathrm{CO_2}$ is released. Also, as HCl is reacted with Zinc it results in release of $\mathrm{ZnCl_2}$ and $\mathrm{H_2}$ gas. And therefore the acidic property of HCl is proven.
In a similar fashion, NaOH on reaction with red litmus solution turns it blue. And when reacted with Sodium Carbonate, NaOH has no reaction. Finally on NaOH reacting with Zinc, products formed are: Sodium Zincate and $\mathrm{H_2}$ gas. Therefore, NaOH exhibits all the properties of a base.
Q1. How can you experimentally identify acids and bases?
Ans. There are various experiments to identify bases and acids. One of which is the litmus test. Using a blue litmus solution you can identify acid and with the red litmus solution the bases. Because, blue litmus turns red on reaction with an acid and red litmus turns blue on reaction with a base.
Q2. What is the importance of base and acid indicators?
Ans. To identify a reaction's end point in a titration experiment, the Acid-base indicators are useful. These are also helpful whole gauging the pH values for different compounds. Also, the intriguing colour change demonstrations in science are also facilitated by Acid-base indicators.
Q3. Is there a possibility of a pH value in negative?
Ans. Although the scale for pH values only covers values between 0-14, the negative pH calculation is possible. In an acid with Hydrogen ion molarity to be greater than the normality of 1N, there is a possibility of negative pH value.
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