16 Questions
Which substance listed cannot be directly identified as an acid or base using olfactory indicators?
Hydrochloric acid (HCl)
Which solution is not a base?
Acetic acid (CH3COOH)
What happens to the odour of vanilla essence when a few drops of dilute HCl are added?
The odour diminishes
Which indicator would turn blue when in contact with a base?
Red litmus
How would the odour of clove oil change if it was tested with a strong base like NaOH?
The odour is masked
What is used to test for acids and bases in Activity 2.2?
Chopped onions in a plastic bag
Which solution would typically exhibit no significant odour change when tested with both dilute HCl and NaOH?
Magnesium hydroxide (Mg(OH)2)
In Activity 2.2, what is the role of dilute HCl and NaOH solutions when added to the cloth strips?
They alter the odour of the onions on the cloth strips.
What is the expected change when you add dilute NaOH to a cloth strip soaked with onion extract?
The odour diminishes
Why are bubbles formed in the soap solution in Activity 2.3?
The gas evolved from the reaction with zinc causes the soap solution to bubble.
Which combination is correct regarding the reaction of phenolphthalein and the listed solutions?
Hydrochloric acid (HCl) - Colourless
What observation is made when a burning candle is brought near a gas-filled bubble from Activity 2.3?
The gas in the bubble catches fire.
Which equation summarizes the reaction of a metal with an acid as described in Activity 2.3?
Acid + Metal $ ightarrow$ Salt + Hydrogen gas
In Activity 2.4, what is added to the test tube containing zinc metal?
Sodium hydroxide solution
What is the chemical name of the bubble-producing gas in Activity 2.3?
Hydrogen
During Activity 2.2, how can one determine if vanilla and clove can be used as olfactory indicators?
By checking if their odour changes in the presence of acids and bases
Study Notes
Understanding Acids and Bases
Identifying Acids and Bases
- Acids and bases can be identified using indicators, which change color in response to acidic or basic conditions.
- Red litmus, blue litmus, phenolphthalein, and methyl orange are common indicators used to test for acids and bases.
Olfactory Indicators
- Olfactory indicators are substances that change odor in acidic or basic media.
- Onion, vanilla, and clove can be used as olfactory indicators.
- Onion cloth strips can be used to test for acids and bases by observing changes in odor.
Reaction of Acids and Bases with Metals
- Acids react with metals to produce hydrogen gas and form a salt.
- The reaction can be summarized as: Acid + Metal → Salt + Hydrogen gas
- Examples of acids that react with metals include HCl, HNO3, CH3COOH, and H2SO4.
- Zinc metal reacts with dilute sulphuric acid to produce hydrogen gas, which can be tested by burning.
- The reaction of a metal with an acid produces a salt and hydrogen gas.
Reaction of Bases with Metals
- Sodium hydroxide solution reacts with zinc metal to produce a salt and hydrogen gas.
- The reaction can be summarized as: Base + Metal → Salt + Hydrogen gas
This quiz assesses understanding of acids and bases in a laboratory setting, including testing and identifying various acid and base solutions.
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