Chem Practical 2 Measure Molar Volume Of Gas Flashcards
What are the main steps of the method to find the molar volume of gas
Place 25 cm³ of 1 mol dm⁻³ ethanoic acid into a boiling tube.
Weigh a specific mass of calcium carbonate (CaCO₃) on a balance (e.g., 0.05 g).
Add the calcium carbonate to the boiling tube containing ethanoic acid.
Quickly seal the boiling tube with a bung connected to a delivery tube leading into a water-filled measuring cylinder inverted in a water bath.
Allow the reaction to finish (bubbling stops when CO₂ production ends).
Record the total volume of carbon dioxide gas collected in the measuring cylinder.
Repeat the experiment with different masses of calcium carbonate (e.g., 0.1 g, 0.15 g, etc.), ensuring the same volume of ethanoic acid is used each time.
Compare results to calculate the molar volume and ensure accuracy by averaging consistent results.
Why must calcium carbonate be in excess?
To ensure all the ethanoic acid reacts, allowing accurate CO₂ measurements
What is the purpose and process of this experiment?
The purpose is to measure the molar volume of a gas by determining the volume of carbon dioxide (
C
O
2
CO
2
) produced when calcium carbonate reacts with ethanoic acid. In this reaction:
Ethanoic acid (
C
H
3
C
O
O
H
CH
3
COOH) reacts with calcium carbonate (
C
a
C
O
3
CaCO
3
) to produce
C
O
2
CO
2
, water, and calcium ethanoate.
The volume of
C
O
2
CO
2
gas is collected in a water-filled measuring cylinder and used to calculate the molar volume of the gas.
How is the molar volume of
Co2
calculated?
Find moles in Caco3 then find Molar volume of carbon dioxide by doing the volume of carbon dioxide collected /moles of caco3
What safety precautions must you follow?
Ensure the delivery tube is not blocked to avoid pressure buildup.
Avoid skin contact with ethanoic acid, as it is corrosive.
Work carefully to prevent gas escape during setup.
What are potential errors in this experiment?
Some
C
O
2
CO
2
may escape before the bung is placed.
The measuring cylinder may not accurately capture all the gas.
Impurities in
C
a
C
O
3
CaCO
3
could affect results.
How can potential errors in the experiment be minimized
Prevent gas escape:
Place the bung securely and immediately after adding
C
a
C
O
3
CaCO
3
to the acid.
Accurate gas collection:
Ensure the delivery tube is submerged in the water in the measuring cylinder.
Check for leaks in the setup before starting the reaction.
Impurities in
C
a
C
O
3
CaCO
3
:
Use high-purity calcium carbonate and ensure precise weighing.
Consistent measurements:
Repeat the experiment multiple times and average the results to reduce random errors.
When I replace bung gas is lost to atmosphere how can I reduce this effect
Use a less reactive acid so rate is lower and gas production is slower so less gas lost
I’m measuring carbon dioxide gas but it dissolves in water how can I reduce the amount lost
Use gas syringe rather than water delivery tube to measure it or saturate water in carbon dioxide gas so it is already “full” with it and won’t dissolve much more
