Oquizy

Xinyi prepares a solution with pH 3 and then dilutes it by adding 90 cm³ of water to 10 cm³ of the solution. What is the expected final pH (assuming ideal dilution)? (pH is the negative log (base 10) of the concentration of hydrogen ions, measured in mol/dm³)

4 5 6 7

To test the effect of acid strength on electrical conductivity, they connect a light bulb to two solutions: 0.1 mol/dm³ HCl and 0.1 mol/dm³ CH₃COOH. Which result and explanation is correct?

Both light the bulb equally because concentration is the same. CH₃COOH lights the bulb more brightly because it's organic. HCl lights the bulb brightly because it ionises fully. Neither lights the bulb because acids don't conduct electricity.

Xinyi performs a titration and records 4 concordant titres: 25.10 cm³, 25.15 cm³, and 25.20 cm³, 25.30 cm³. What volume should be used for calculations?

25.10 cm³ 25.15 cm³ 25.20 cm³ Average of any three readings

25.0 cm³ of NaOH (unknown concentration) is neutralised by 20.0 cm³ of 0.10 mol/dm³ HCl. What is the concentration of NaOH?

0.05 mol/dm³ 0.08 mol/dm³ 0.10 mol/dm³ 0.12 mol/dm³

In a weak acid–strong base titration, the pH changes from ~3 to ~11 over 10 cm³. Which indicator is most suitable?

Bromothymol blue Methyl orange Phenolphthalein Universal indicator

A solution has a pH of 4. After diluting it 100 times with water, what is the approximate pH? (pH is the negative log (base 10) of the concentration of hydrogen ions, measured in mol/dm³)

2 4 6 8

While standing near the fertilizer storage, John asks why factories don't just lower the temperature even further in the Haber process to get more ammonia. Xinyi rolls her eyes and says the main reason is:

Ammonia decomposes quickly at low temperatures High temperature prevents ammonia poisoning Lower temperatures cause excess hydrogen to form The reaction rate would be too slow for practical production

Xinyi challenges John: 'If 1000 moles of nitrogen react with excess hydrogen at 250 atm and 450°C, assuming 15% conversion per pass, how many moles of ammonia are produced in one pass?'

1000 150 300 500

John attempts to prepare lead(II) sulfate in the lab. Which pair of solutions will give him the desired product through precipitation?

Lead(II) carbonate and hydrochloric acid Lead(II) nitrate and sodium chloride Lead(II) nitrate and sulfuric acid Lead(II) oxide and nitric acid

Xinyi mistakenly added insufficient copper(II) oxide to her sulfuric acid. What is the likely problem with the resulting solution after filtration?

It contains unreacted base It does not contain any copper ions It is neutral and ready for crystallisation It still contains excess acid

To prepare magnesium sulfate from magnesium carbonate, what steps should be followed?

Add equal amounts of carbonate and acid, then evaporate immediately Add excess carbonate to sulfuric acid, filter off excess solid, and crystallise the filtrate Mix magnesium carbonate and magnesium sulfate solutions, and evaporate Use titration since both reactants are soluble

Quiz: Chemistry - Acid-Base Chemistry