Exploring Substances: Acidic, Basic, and Neutral

Flashcards covering acidic, basic, and neutral substances, natural and synthetic indicators, and neutralisation reactions in everyday life.

What is an indicator in chemistry?

A chemical substance used to determine whether a solution is acidic, basic, or neutral by showing a distinct change in colour or smell.

From which natural organism is litmus dye extracted?

Lichens, which are formed by the close partnership of a fungus and an alga.

What color change occurs when blue litmus paper is exposed to an acidic solution?

It turns red.

What color change occurs when red litmus paper is exposed to a basic solution?

It turns blue.

From which Latin word is the term 'acid' derived, and what does it mean?

It comes from the Latin word acere, which means sour.

Which acid is commonly found in citrus fruits like lemons and oranges?

Citric acid (and ascorbic acid / Vitamin C).

Which acid is injected into the skin during an ant or honey bee sting?

Formic acid.

Which acid is found in curd and dairy products?

Lactic acid.

Which acid is present in tamarind and grapes?

Tartaric acid.

Which acid is the main component of vinegar?

Acetic acid.

Which acid is naturally present in tomatoes?

Oxalic acid.

What chemical name and formula correspond to quicklime (chuna)?

Calcium oxide ($\text{CaO}$).

What clear, slightly alkaline liquid is formed by dissolving calcium oxide ($\text{CaO}$) in water and filtering the mixture?

Lime water, which is a solution of calcium hydroxide ($\text{Ca(OH)}_2$).

What base is found in milk of magnesia?

Magnesium hydroxide.

What are water-soluble bases called?

Alkalies.

How does red rose extract react when added to acidic and basic solutions?

It turns red in acidic solutions and green in basic solutions.

What colour change is observed when turmeric paper is exposed to a basic substance?

It turns reddish-brown.

What active natural component of turmeric enables it to act as an acid-base indicator?

Curcumin.

How do the flower colours of the Hydrangea plant differ based on soil pH?

Acidic soil produces blue-coloured flowers, while basic soil produces pink or red flowers.

What are indicators whose odour changes in acidic or basic media called?

Olfactory indicators (e.g., onion, clove oil, and vanilla).

What happens to the odour of onion when it is exposed to a basic solution such as baking soda?

The odour weakens or disappears completely.

Who is widely regarded as the 'Father of Modern Indian Chemistry'?

Acharya Prafulla Chandra Ray.

In what year did Acharya Prafulla Chandra Ray establish India's first pharmaceutical company?

1901.

What type of chemical process occurs when an acid reacts with a base to form salt, water, and heat?

A neutralisation reaction.

What basic substance can be applied to neutralise the formic acid from an ant bite?

Moist baking soda or calamine solution (zinc carbonate).

How should soil that has become too acidic due to excessive chemical fertilisers be treated?

It should be treated with lime (a base) such as quicklime or slaked lime.

Which acid is secreted by human stomach walls to aid digestion?

Hydrochloric acid.

Why do milk vendors in warm climates add a small amount of baking soda to fresh milk?

To neutralise excess lactic acid produced by natural bacteria and prevent curdling.

What gas causes bubbling when vinegar reacts with calcium carbonate ($\text{CaCO}_3$) in an eggshell or marble?

Carbon dioxide gas ($\text{CO}_2$).

What colour does synthetic indicator phenolphthalein show in a basic medium?

Pink (and colourless in an acidic medium).