How Strong Are Acid or Base Solutions – Long Answer Questions

Medium Level (Application & Explanation)

Answer:

The pH scale ranges from 0 to 14. It shows how acidic or basic a solution is.
A pH less than 7 means the solution is acidic. A lower pH means a stronger acid.
A pH of 7 means the solution is neutral, like pure water or clean tap water.
A pH greater than 7 means the solution is basic. A higher pH means a stronger base.
Daily examples: lemon juice (pH ~2) is strongly acidic; coffee (pH ~4.5–5) is acidic; baking soda (pH ~9) is a weak base.
1M HCl (pH ~0) is a strong acid, and 1M NaOH (pH ~14) is a strong base.

Answer:

Take a clean strip of pH paper or add a few drops of universal indicator to the solution.
Dip the strip briefly, then compare the color with the pH color chart.
Note the exact color and find the closest pH value on the scale.
Record the solution name, the color, the approximate pH, and its nature (acidic, neutral, or basic).
Example: saliva before meal may show greenish-yellow (pH ~6.5–7.5), while 1M HCl turns red (pH ~0–1).
Follow safety: do not touch acids or bases; rinse strips properly; work with small quantities only.

Answer:

Strength depends on how much the substance dissociates to give ions in water.
A strong acid gives a high concentration of H+ ions. It fully dissociates. Example: HCl.
A weak acid gives fewer H+ ions. It partly dissociates. Example: acetic acid (CH3COOH).
A strong base gives a high concentration of OH− ions and fully dissociates. Example: NaOH.
A weak base gives fewer OH− ions and partly dissociates. Example: baking soda solution.
So, pH shows how many ions are present. Strength shows how completely the acid or base forms ions.

Answer:

Soil pH affects plant growth. Some plants like acidic soil (blueberries, pH ~5). Others prefer slightly basic soil (asparagus).
Farmers test soil and use lime to reduce acidity or sulphur to reduce alkalinity.
Rainwater is slightly acidic (pH ~5.6). If it falls below 5.6, it is acid rain. It can harm fish, soil, and buildings.
The stomach has strong acid (pH ~1.5–3.5) to digest food and kill germs.
Antacids (weak bases) help when acid is too much. They neutralize extra acid.
Thus, pH guides agriculture, environment care, and health choices.

Answer:

Bee stings inject acidic venom. Applying baking soda (a mild base) helps neutralize the acid.
Nettle stings contain methanoic acid. Rubbing a basic paste can reduce the burning.
Ant stings are also acidic, often causing itching and pain. A base helps relieve it.
The idea is: an acid reacts with a base to form salt and water. This is neutralization.
Do not scratch. Wash the area and apply the correct opposite (base for acid stings).
If the sting is severe, seek medical help. Neutralization gives quick first aid relief.

Answer:

pH 6 is acidic. pH 8 is basic.
Each 1 pH unit means a 10× change in H+ concentration.
So, the pH 6 solution has 100 times more H+ than the pH 8 solution.
On universal indicator, pH 6 shows yellow-green; pH 8 shows green-blue.
pH 6 may be like saliva after meal or tomato juice. pH 8 may be like slightly alkaline water.
Thus, even a small pH change means a big change in ion concentration and strength.

Answer:

The soil is too acidic for many crops. It may reduce yield.
Add quicklime (CaO) or slaked lime (Ca(OH)2) to raise pH. They neutralize excess H+ ions.
Mix lime evenly into the soil. Apply in small doses and retest pH after some weeks.
Choose crops that can tolerate acidity while the soil is being corrected.
Improve organic matter. Compost can buffer pH and improve soil health.
Avoid over-liming. Too high pH can lock nutrients and harm plants.

Answer:

The pH 2 sample is more acidic than pH 4.
The H+ concentration at pH 2 is 100 times higher than at pH 4.
But pH tells acidity at that moment, not necessarily strength of the acid type.
A strong acid like HCl fully dissociates. A weak acid like acetic acid partly dissociates.
A concentrated weak acid may show a low pH, similar to a dilute strong acid.
So, to judge strength, check dissociation behavior, not pH alone.

Answer:

The drop suggests acid rain input. It forms from SO2 and NOx gases in the air.
At pH 4.5, fish and aquatic life may face stress or death.
Acidic water can leach metals from soil and pipes, harming organisms.
If the lake has limestone rocks, they may buffer the acid somewhat.
Remedies: reduce industrial emissions, use clean fuels, and plant trees.
Local action: add limestone (CaCO3) powder to neutralize and slowly raise pH.

Answer:

The stomach works best at pH 1.5–3.5 with HCl for digestion.
Antacids are weak bases. They neutralize excess acid and give relief.
Common ones include magnesium hydroxide and calcium carbonate.
They should be used for short-term relief, not as a daily habit.
Overuse may cause alkalinity, gas, or constipation/diarrhea.
If acidity is frequent, see a doctor. Check diet and lifestyle too.

Answer:

Lemon juice: pH ~2. Color: red/orange. Strongly acidic.
Coffee: pH ~4.5–5. Color: yellow/orange. Acidic.
Tap water: pH ~7. Color: green. Neutral.
1M NaOH: pH ~14. Color: dark blue/purple. Strongly basic.
Order of acidity: Lemon juice > Coffee > Tap water > 1M NaOH (opposite end, basic).
Safety: wear gloves, avoid skin contact, use small amounts, and rinse spills.

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