Question

how would you prepare a sample of carbon monoxide in the laboratory.​

Answer 1

Answer:

Carbon monoxide (CO) is iso-electronic with nitrogen (N2) and formed through the incomplete combustion of carbon, (7.5. ... A convenient laboratory preparation of CO is the dehydration of formic acid by sulfuric aci d

Answer 2

MAKING CARBON MONOXIDE

Carbon monoxide is made industrially in the manufacture of synthesis gas from the reaction of alkanes with steam. In the laboratory, an easy way to prepare CO is by the dehydration of concentrated methanoic acid using concentrated sulfuric acid1.

HCOOH(l) → CO(g) + H2 O(l)  

The CO evolved can then be ignited to show that the gas burns with a pale blue flame.  

 

KIT

• 250 ml conical flask with a bung attached to a delivery tube for collecting over water;

• trough filled with water, beehive shelf, gas jars and cover slips;

• 50 ml concentrated sulfuric acid;  

• 50 ml concentrated methanoic acid;  

• a splint attached to a metre rule to be used as a taper;  

• nitrile gloves, goggles and a ducted (not filter or recirculatory) fume cupboard.

SAFETY

Perform both the preparation and demonstration in a ducted fume cupboard. Filter (re-circulatory) fume cupboards must not be used because carbon monoxide is not absorbed by the filters. Concentrated sulfuric and methanoic acids are corrosive and can cause severe burns to the skin and eyes. Wear goggles (or face shield) and nitrile gloves throughout, and take great care igniting the CO gas in case of an explosion. The amount of methanoic acid suggested could produce up to 30 litres of CO gas. Carbon monoxide's toxicity requires that the apparatus must remain in a fume cupboard and that the products are carefully poured into a large volume of water (or, better, a mixture of ice and water) and then disposed of down the fume cupboard sink and washed away with plenty of cold water.

PROCEDURE

In a ducted fume cupboard pour 50  ml of concentrated methanoic acid into a 250 ml conical flask and then carefully add 50 ml of concentrated sulfuric acid. Stopper the flask with the rubber bung containing the delivery tube and gently swirl the mixture. You should see a reaction start, producing bubbles of carbon monoxide. Leave the apparatus to stand for ca  30 seconds, to ensure the air is flushed from the conical flask, before collecting the gas over water. Carefully ignite the gas collected in the gas jar. Once you have proved that the carbon monoxide is not mixed with air (ie it burns quietly, with no explosion), you could quickly replace the delivery tube with a jet (vertical glass delivery tube) and ignite the gas at the jet. (Note: this will be tricky because CO will be being given off.)

Don't panic if a bit of CO escapes into the classroom; anything less than about 20 litres will not raise the concentration to toxic levels.  

 

complete combustion:  

CH4 (g) + 2O2 (g) → CO2 (g) + 2H2 O(g)  

inadequate oxygen supply:  

CH4 (g) + 1.5O2 (g) → CO(g) + 2H2 O(g)

inadequate oxygen supply:  

CH4 (g) + O2 (g) → C(s) + 2H2 O(g)  

With sixth form groups the structure of CO can be discussed, starting with a proposed Lewis dot-and-cross diagram followed by a discussion of the proposed resonance structure of CO.