Advanced Higher Chemistry - Researching Chemistry

Which one of the following is not suitable for the preparation of a primary standard in volumetric analysis?

• Anhydrous sodium carbonate

• sodium hydroxide

• oxalic acid

• Potassium iodate

The most appropriate pieces of equipment to use when diluting a solution by a factor of 10 would be

• a 10 cm³ pipette and a 100 cm³ measuring cylinder

• a 10 cm³ pipette and a 50 cm³ standard flask

• a 25 cm³ measuring cylinder and a 50 cm³ standard flask

• a 25 cm³ pipette and a 250 cm³ standard flask

An excess of sodium sulfate was added to a solution of a barium compound to precipitate all the barium ions as barium sulfate, BaSO₄. (GFM of BaSO₄ = 233·4 g). How many grams of barium are in 0·458 g of the barium compound if a solution of this sample gave 0·513 g of BaSO₄ precipitate?

• 0.032 g

• 0.055 g

• 0.269 g

• 0.302 g

Sodium hydroxide is unsuitable for use as a primary standard because it

• is corrosive

• is readily soluble in water

• is available in a high degree of purity

• readily absorbs water from the atmosphere

What volume of 0·25 mol l^-1 calcium nitrate is required to make, by dilution with water, 500 cm³ of a solution with a nitrate ion concentration of 0·1 mol l^-1 ?

• 50 cm³

• 100 cm³

• 200 cm³

• 400 cm³

The concentration of Pb²⁺ ions in a solution can be determined using the sequence of reactions shown. How many moles of Iodine are formed from one mole of Pb²⁺ ions in the solution?

• 0.75

• 1.5

• 3.0

• 6.0

Which of the following compounds could be used as a primary standard?

• calcium carbonate

• hydrochloric acid

• sodium carbonate

• sodium hydroxide

Which of the following techniques can be used to both purify and identify a compound?

• distillation

• recrystallisation

• solvent extraction

• melting point determination

Which of the following techniques could be used to purify an impure sample of solid caffeine?

• TLC

• Heat under reflux

• Recrystallisation

• Distillation

Using colorimetry, the most appropriate filter for determining the concentration of green nickel ions, Ni²⁺ (aq), in a solution, would be

• 390 nm

• 490 nm

• 540 nm

• 680 nm