CPAC A4: determining the molar gas volume

Question 1

measuring molar volume of gas

Answer 1

• meausring cylinder to measure a known excess volume of acid into a conical flask. eye level at bottom of mensicus
• tar+zero balance, measuring mass of solid. place in conical flask so vial doesnt spill
• attach flask to gas syringe and insert pung. push down so its airtight
• swirl conical flask so mass comes into contact with acid
• record volume of co2 in gas syringe at the end
• repeat for more gases- ENSURING MASS DOESNT EXCEED CAPACITY OF GAS SYRINGE

Question 2

PROCESSING DATA

Answer 2

mass of solid x axis
volume co2 y axis
- choose a data point
- work out moles of solid
- volume/moles = molar gas volume

Question 3

assumption in calculation

Answer 3

moles co2 = moles caco3

Question 4

problem in gas syringe

Answer 4

• gas escapes before bung inserted
• stiff plunger in syringe. use lubricant
• bung not airtight, gas lsot to atmosphere so volume lower
• low room temp = lower molar volume