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AOS1 CHEM > Energy from Fuels > Flashcards

Energy from Fuels Flashcards

1
Q

Can energy be created or destroyed?

A

No

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2
Q

Where is chemical energy stored in atoms

A

In their bonds

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3
Q

When chemical reaction or a physical change occurs, happens to the bonds

A

the chemical energy changes

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4
Q

What are biofuels?

A

Fuels derived from biomass such as cellulose,starch,plants.

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5
Q

It is said that biofuels do not contribute to the net output of co2, is this true and how

A

Yes, as the plants absorbs the same amount of CO2 as the source that generates CO2 upon combustion, burning the biofuel replaces the carbon dioxide that plants absorbed during photosynthesis.

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6
Q

What are the biofuels u should know

A

Bioethanol, biodiesel, biogas

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7
Q

would it biofuel if some biofuel is blended with fossil fuels like petrol and diesel?

A

Yes, that is still biofuel

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8
Q

What is the photosynthesis equation

A

6CO2(g) + 6H20(l) —–> C6H1206(aq) + 602(g)

DONT FORGET UV LIGHT AND CHLOROPHYLL ON EQ LINE

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9
Q

What do plants do with the glucose that is produced

A

They can be stored as starch and cellulose

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10
Q

What is photosynthesis

A

An endothermic process used by plants and some bacteria to make glucose from CO2 and water, converting light energy abosrved by chlorophyll.

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11
Q

How is biogas made

A

Biogas is made when biomass/biowaste decays in anerobic conditions(lack of oxygen)

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12
Q

What is biogas mainly consisted of.

A

Mainly CH4 methane (64%) and carbon dioxide CO2 (32%)

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13
Q

What is process called for when bacteria break down organic waste and its products

A

Anerobic fermentation
Produces methane and carbon dioxide which forms the biogas.

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14
Q

Biogas contains CO2, does that affect the combustion process and why

A

No, the co2 DOES NOT combust, and therefore does not affect the combustion process. This is as the CO2 cant further combust as it is ** fully oxidised** and therefore deos not release any energy.

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15
Q

Biodiesel and petrodiesel is pure substance true or false

A

False

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16
Q

How are biodiesels fromed from

A

vegetable oils sourced from plants (or animal fats) by reaction with alkanol(methanol)

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17
Q

On a common structural formula of biodesel molucele, where is the ester group and the methyl group.

A

Ester group- The c double bonded to oxygen
Methyl group- the end group that has 3 Hs and 1 oxygen

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18
Q

What does petrodisel contain of

A

75% alkanes and 25% aromatic hydrocarbons.

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19
Q

what are fats and oils?

A

Fats and oils are triglycerides with three ester groups and three hydrocarbon chains

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20
Q

What is the process that biodisel is made from and what is the products

A

Transestrification
1.Glycerol
2.3 esther molecules with long hydrocarbons chains ( 3 biodisels)

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21
Q

Why are the esters prodcued in transestrifciation often methyl esters

A

Because the alchol used is methanol

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22
Q

Where is a catalyst used i nthe whole biodeisel making part AND WHAT IS IT

A

Transestrication process.
The catalyst is KOH

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23
Q

Why are fossil fuels non-renewable

A

Fossil fuels are non-renewable source of energy. Took millions of years to form so cannot be replenished in the near future.

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24
Q

What is the primary source of energy for all plants and animals

A

Glucose

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25
What are the two types of cellular respiration
Aerobic respiration: Requires oxygen. Main source of energy for humans. Anaerobic respiration: Does not need oxygen, yields less energy
26
In aerobic cellular respiration, what happens to the glucose
It is **oxidised** into H20 and CO2
27
What is overall equation of cellular respiration
C6H12O6 (aq) + 6O2(g) = 6CO2(g) + 6H2O(l)
28
Which process , anerobic or aerobic respiration, yields more energy per glucose molecule and which one is faster
Aerobic respiration yeilds more energy but anerobic is faster
29
Is cellular respiration (aner and aero) exothermic or exothermic
Exothermic
30
Energy content of food is measured in WHAT UNITS
1.kJ/mol 2.kJ/g 3.kJ/100g
31
What is energy value
energy available to the human body from a nutrient or food ## Footnote this important cause if a question asks that, u gotta null the celluose content.
32
What are the 3 main macronutrients
1.Carbohydrates ( C,H,O) 2.Protiens 3.Fats ( lipids)
33
What macronutrient is glucose
Carbohydrate ## Footnote simple carbohydrate
34
What is a structural isomer
Same molecular formula but different arrangement of atoms
35
What is glucose classified into?
Monosaccarachides, disaccaridies, Polysaccharides
36
What are some examples of monosaccarachides?
Glucose,fructose, galactose ( They are **structural isomsers**)
37
How is a disaccharide formed
When two monosachrides undergo condensation reaction, they form disaccaharide ( and water)
38
What happens when many monosaccharides undergo condensation
A polysachharide is formed ( such as cellulose, starch)
39
Is glucose soluble? explain
Yes it is **HIGHLY SOULUBLE**, as it contains numerous **polar** **hydroxyl** groups (OH) that are capable of forming **hydrogen** bonds with water.
40
What is the process by which a polysaccharide is broken down to form monosaccharides like glucose is called
Hydrolysis
41
Is glucose solid or aq state at room temp
Solid
42
What happens during digestion after eating starch or carbohydrates
enzymes in our saliva and intestine , breakdown starch molecules back into glucose. The glucose is then moved from the digestive system into cells where celluar respiration occurs via the use of red blood cells. Energy is then released.
43
What are enzymes
organic catalysts that alter the rate of biochemical reactions
44
What happens to fats and oils during breakdown
components of the breakdown can be **oxidised** in body cells to produce CO2 and H20, releasing large quantities of energy.
45
Are the parts the fats and oils can be broken down into
1.Glycerol 2.Fatty acids
46
Are protiens are high in energy
Rarely used by the body as a energy source
47
Why is the energy value of fats and oils higher?
Fats and oils are not as partially oxidised compared to carbohydrates for eg, therefore have greaer potential oxidation and would release more energy on combustion
48
Why is there a slight difference between the heat of combustion and energy value? When getting energy from carbs,fats,protiens
1.Incomplete absorption of nutrients by the body after digestion 2. Incomplete oxidation of nutrients like protiens and insouluble fibres 3. Heat loss: not all the energy released by the oxidation of glucose is availble for the cells
49
What is fibre also known as
Cellulose
50
Can humans breakdown celluose? | explain
No we cant, as we lack the enzyme required ( cellulase) and therefore passes through our digestive system and cant abosorb any energy from it.
51
Is ethanol renewable?
Depends, it is considered renewable if it is made through natural process ( bioethanol) . If it is made from crude oil , then it is not sustainble as it is made from fossil fuels which is decaying organic matter that takes millions of years to form
52
How is bioethanol produced?
Yeast undergoes **fermentation**, where starch is broken down to glucose which is further catalysed by enzymes into ethanol and CO2.
53
What is the fermentation equation:
CH3CH2OH(l) +3O2(g)-------> 2CO2(g) + 3H2O(l)
54
what is E10 petrol
E10 petrol contains 10% ethanol and the rest is petrol.
55
Why would you need more bioethanol than petrol to run the same distance
Energy content of ethanol is 62% that of petrol, so larger amount of ethanol is needed to provide the same energy
56
The stronger the bonding of the carbohydrates in the feedstock, the___ | finish it off
greater the pretreatment required to ensure the enzymes are effective.
57
Why is sugar cane so good for fermentation?
Sugar cane is high in sucrose ( simple sugar) , which is **small** and **highly souluble** therefore does not require pretreatment.
58
Why is wheat and forest waste bad for fermenation
Wheat is high in starch Forest waste is high in celluose Which is difficult to process as the hydrogen bonds holding the cellulose molecules together are strong, requires harsh pre-treatment with steam and specialised enzymes to break cellulose into glucose
59
What is distillation
A process used to seperate components of a mixture based on their boiling points
60
What state is bioethanol when made from fermentation.
Liquid mixed with water
61
Why does bioethanol need distillation
Because it contains water initally, and would make it difficult to burn the ethanol when dissolved in water
62
What is BP for water and ethanol
Water: 100c Ethanol: 78C
63
What happens in the distillation of bioethanol
A solution is heated to the boiling tempreature of ethanol (78) which then it will vaporise, which can be condensed and collected as distillate. The water is then left.
64
Why carbon neturality dismissed due to the distillation process of bioethanol?
Significant energy is required to boil ethanol solution
65
Why is bioethanol not considered Carbon netural
1. Energy is required and would cause for the emissions of carbon during the process of **growing,transport** and **refining** of bioethanol 2. Bioethanol produces much less energy than the same volume of petrol. And therefore would require more ethanol to be combusted to produce similar energy amounts, which consequently will produce more co2 emmisions.
66
If they ask why there is a difference in experimental and heat of combustion. And specfically say other than energy loss to surroundings
* The combustion could have been incomplete. * Water not stirred and heat energy unevenly distributed resulting in thermometer measuring lower temperature. * Heat energy unevenly distributed resulting in thermometer measuring lower temperature. * Volume of water greater than 200 mL. * Parallax reading of thermometer giving lower temperature. | Dont SAY SLC out of no where
67
what to mention whrn asked why temp decreased after 70 minutes in temp time graph calorimetetry
The food had stopped burning/fkane was extinguished ( 1mark) and the calorimeter was not proeprly insulated and therefore heat is lost to the sureounding.

AOS1 CHEM (3 decks)

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