6. Bio-LPG is a co-product in the manufacture of bio-diesel from renewable crops and domestic and industrial waste - Leaving Cert Chemistry - Question 6 - 2021
Question 6
6. Bio-LPG is a co-product in the manufacture of bio-diesel from renewable crops and domestic and industrial waste. Hydrogen gas is a reagent in the production of th... show full transcript
Worked Solution & Example Answer:6. Bio-LPG is a co-product in the manufacture of bio-diesel from renewable crops and domestic and industrial waste - Leaving Cert Chemistry - Question 6 - 2021
Step 1
Give two commercial sources of hydrogen gas.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Steam reforming of natural gas (coal gasification).
Electrolysis of water.
Step 2
State two main advantages of using hydrogen gas itself as a fuel.
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Hydrogen is low polluting, non-toxic, and produces no greenhouse gases during combustion.
It is efficient with a high energy density, providing high calorific value.
Step 3
What are the two main hydrocarbon components of LPG?
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Propane (C3H8)
Butane (C4H10)
Step 4
With the aid of a labelled diagram explain how crude oil is fractionally distilled.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Crude oil is heated in a distillation column where fractions of different boiling points separate. Lighter fractions rise to the top and heavier fractions condense lower in the column. A labelled diagram will show the column with crude oil input at the bottom, and different fractions being drawn off at various heights, showing their respective boiling points.
Step 5
Show on your diagram where the refinery gas and gas oil fractions separate.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
On the labelled diagram, the refinery gas will condense at the upper part of the distillation column, while gas oil will be drawn from a lower point in the column.
Step 6
What is the purpose of adding mercaptans to natural gas or LPG?
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The purpose of adding mercaptans is to provide a distinctive smell to the gas, enabling leaks to be detected easily.
Step 7
Calculate the heat of formation of ethanol.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Using the reaction:
ightarrow 2 ext{CO}_2(g) + 3 ext{H}_2 ext{O}(l) + ext{SO}_2(g)$$
The heat of formation of ethanol can be calculated as:
$$\Delta H_{f} = \Sigma \Delta H_{formation} – \Delta H_{combustion}$$
Substituting the values:
$$ \Delta H_{f} = (-787.0 - 857.4 - 296.8) - (-1867.5) \Rightarrow -1941.2 + 1867.5 = -73.7 \, kJ \, mol^{-1}$$
Join the Leaving Cert students using SimpleStudy...
