AS1 core practicals

Question 1

Method to measure the molar volume of a gas

Answer 1

Measure 30 cm3 of 1 mol dm-3 ethanoic acid and transfer to a conical flask.

Attach conical flask to gas syringe or use collection over water method

Measure the mass of a weighing bottle with approximately
0.05 g of calcium carbonate

Add the calcium carbonate to the conical flask- quickly resealing the bung so no gas escapes

Measure the final total volume of gas

Reweigh the empty weighing bottle test tube from step 3

Repeat the experiment several more times, increasing the mass of calcium carbonate by about 0.05 g each time.

Answer 2

Weigh the sample bottle containing the required mass of solid on a 2 dp balance

• Transfer to beaker
• Reweigh empty sample bottle
• Record the difference in mass
• Add 100cm3 of distilled water to the beaker. Use a glass rod to stir to help dissolve the solid.
• Pour solution into a 250cm? graduated flask via a funnel.
• Rinse beaker and funnel and add washings from the beaker and glass rod to the volumetric flask.
• make up to the mark with distilled water using a dropping pipette for last few drops.
• Invert flask several times to ensure uniform solution.