Question

(a) Which element is common to all acids?
(b) Compounds such as alcohol and glucose also contain hydrogen but are not categorised as acids. Describe an activity to prove it.

Answer 1

Answer:(a)Hydrogen

(b)

Take the solution of dilute hydrochloric solution and glucose. Two nails are fitted on a cork and are kept it in a 100 mL beaker. The nails are then connected to the two terminals of a 6-volt battery through a bulb and a switch. Dilute HCl is poured in the beaker and current is switched on. Now, the Same experiment is performed with a glucose solution and an alcohol solution.

We will observe that the bulb glows in HCl solution and does not glow in the glucose solution.

Because: HCl dissociate into H + (aq) and Cl -(aq) ions. These ions conduct electricity in the solution resulting in the glowing of the bulb. On the other hand, the glucose solution does not dissociate into ions. Therefore, it does not conduct electricity.

Conclusion:

From this activity, it can be concluded that all acids contain hydrogen but not all compounds containing hydrogen are acids. That is why, though compounds like alcohols and glucose contain hydrogen, they are not categorized as acids.

Explanation:

Answer 2

Explanation:

(a) Common element in acids:

• The element widely found in acids is hydrogen but not all the hydrogen containing compounds are acids.
• A compound exhibits acidic nature when it is dissolved in aqueous solution and donates proton (mostly hydrogen atom).
• The acids are categorised into strong and weak acids based on the bonds they form.

(b) Alcohol and glucose:

• The formula of glucose is $C_{6} H_{12} O_{6}$ which obviously has hydrogen atom.
• The formula of alcohol is hydrocarbon with hydroxyl group (-OH) which obviously has hydrogen atom.
• Following steps are followed to prove that glucose and alcohol does not come under acids:
• Step 1: Place a glass beaker and place a cork in its bottom. Two nails are fixed in the cork.
• Step 2: Nails are connected to battery with bulb in it.
• Step 3: Pour dilute HCl into the beaker, the electricity is passed through the wire.
• Step 4: The HCl dissociates into H^+ (proton) and Cl^- (electron) ions which glows the light.
• Step 5: Pour glucose or alcohol into beaker with similar setting and similar experiment is repeated.
• Step 6: The glucose or alcohol does not dissociate into hydrogen atom and the light does not glow.
• Thus, acids contain hydrogen atom but not all the compound with hydrogen atom are acids.
• Hence proved.