Quiz 4 : Gravimetry and Volumetry Analysis

What would happen to the weighed mass if some precipitate seeped through the filter paper?

• mass would be too high

• molar mass would be too low

• There would be no effect on the molar mass

• The mass of the precipitate collected would decrease

If a student forgot to cover their experiment with parafilm over the weekend before they filtered their product, how would that affect the calculated molar mass?

• molar mass would be too low

• molar mass would be too high

• molar mass would be unaffected

• molar mass would certainly double

If you failed to heat the crucible enough times for the masses to be consistent, why would that cause your calculated molar mass to be too high?

• the presence of water causes the mass of the unknown carbonate to be too high

• the moles of calcium carbonate increases

• the mass of the unknown carbonate will be too low

• the moles of the unknown carbonate will be too high

25.0 cm³ of sodium hydroxide solution is tritrated against 0.200 mol dm^–3 hydrochloric acid until the indicator just changes colour. 27.5 cm³ of the acid are required to reach the end point.

Phenolphthalein is used as an indicator in the above experiment. What will be its colour change at the end point?

• From red to yellow

• From red to colourless

• From yellow to colourless

• From yellow to red

To prepare a solution of accurately known volume, use a

• measuring cylinder

• beaker

• concial flask

• volumetric flask

A standard solution is a solution with accurately known concentration.

• True

• False

The point in an acid-alkali titration at which the reactants just react completely with each other is called the __________ point.

• end point

• equivalence point

__________ is a suitable indicator for the titration of a strong acid and a weak alkali.

• Methyl orange

• Phenolphthalein

• Litmus solution

• Universal indicator

During a titration, the end point and the equivalence point always occur at the same time.

• True

• False

20 cm³ of 1 mol dm^–3 CH₃COOH(aq) and 10 cm³ of 1 mol dm^–3 H₂SO₄(aq) require the same number of moles of NaOH for complete neutralization.

• True

• False