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Topic 9 - Can We Live A Chemical Free Life? > Part 1 - What Are Chemicals And Are They Safe? > Flashcards

Part 1 - What Are Chemicals And Are They Safe? Flashcards

1
Q

What do you understand by the term compound?

A

A compound is a substance that consists of two or more elements chemically bonded in a definite ratio to one another

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2
Q

What is a chemical?

A

The Oxford dictionary gives two definitions for the noun chemical

A distinct substance, especially one which has been chemically prepared or purified

An intoxicating or psychoactive drug

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3
Q

Is water a chemical?

A

It is a compound containing of hydrogen and oxygen

So according to the definition of chemical it is regarded as a chemical

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4
Q

What do you think manufacturers mean when they regard a product as ‘chemical free’?

A

Perhaps they are referring to whether the product has natural or synthetic compounds

Maybe artificial or synthetic chemicals are more toxic and therefore natural products are better for our health

It turns out that two of the most toxic chemical compounds are botulinum and tetanospasmin which are both natural or naturally occurring

Even our own bodies can produce chemical compounds that are harmful to our body such as histamine

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5
Q

What is the chemical formula of histomine?

A

Histamine contains 5 carbon atoms, 9 hydrogen atoms and 3 nitrogen atoms

The chemical formula is C5 H9 N3

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6
Q

What are organic molecules?

A

Organic molecules are composed of carbon atoms in long chains or rings with other atoms such as oxygen, hydrogen and nitrogen attached

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7
Q

What modern day materials are produced from the key components of organic materials?

A

Plastics
Detergents
Food flavourings
Drugs in medicine

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8
Q

What raw material do we produce many of our modern day materials from?

A

Crude oil

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9
Q

How was crude oil formed?

A

It was formed from ancient sediments. Over millions of years these ancient sediments were turned in to rock

Due to certain conditions in earths history the biological material in the sediments underwent a chemical transformation to produce oil

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10
Q

What do the different components of crude oil consist mainly of?

A

Carbon and hydrogen

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11
Q

What is each component do crude oil known as?

A

A fraction

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12
Q

What is the physical process that separates the mixture of crude oil?

A

Distillation

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13
Q

How many carbon and hydrogen atoms does butane have?

A

Butane has four carbons and ten hydrogen atoms

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14
Q

what is abbreviated structural formula?

A

It is a diagram representing a chemical compound. In this example butane is used, When drawing the full structural formula of butane, we place all four carbon atoms in a row. We then draw single lines, representing a single covalent bond, between each of the carbon atoms. The next stage is to mark out the hydrogen atoms.

the abbreviated structural formula of butane

CH3 -CH2-CH2-CH3

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15
Q

What are alkanes?

A

They are the class of compounds containing only carbon-carbon single bonds and carbon-hydrogen bonds

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16
Q

what is a Branched carbon chain?

A

Branched-chain hydrocarbons are compounds in a category consisting of molecules with a branch in the chain of carbon; i.e. you cannot represent the connected chain as a linear chain, because at some point or other there is a ‘fork’ in the chain

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17
Q

what are isomers?

A

They are Molecules with the same number but a different arrangement of atoms. ie linear and branched
The chemical names of the isomers are also different
for example butane and methylpropane both have the chemical formula or C4H10
but they are both arrange in different ways

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18
Q

What is the skeletal formula?

A

skeletal formula as it just shows the skeleton of the molecule. Like a zig zag

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19
Q

what are cycloalkanes?

A

It is Another type of hydrocarbon found in crude oil are cycloalkanes. Cycloalkanes are hydrocarbons whose structures involve carbon atoms joined in a ring (cycle) by single bonds.

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20
Q

In cyclohexane (see Figure 1.11a), how many carbon atoms are bonded to each carbon?

A

Each carbon is bonded to two other carbons.

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21
Q

In cyclohexane, how many hydrogen atoms are bonded to each carbon?

A

Each carbon is bonded to two hydrogen atoms

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22
Q

Describe what aromatics are in crude oil?

A

The other class of hydrocarbons present in crude oil is the aromatics. These are compounds that have a characteristic group in which six carbon atoms are joined in a ring with alternating double and single bonds, as shown in Figure 1.12. We normally represent a carbon-carbon double bond in structural formulas as C=C.

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23
Q

What is a double bond?

A

A double bond is a chemical bond between two atoms sharing four electrons instead of the two electrons shared in a single bond.

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24
Q

What percentage of crude oil is converted into petrochemicals?

A

Around 5% of crude oil is converted into petrochemicals

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25
Q

What are petrochemicals?

A

They are converted from crude oil and become plastics, pesticides, drugs, adhesives, paints and solvents

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26
Q

Define the term ‘cracking’ related to the process of converting hydrocarbons?

A

The first stage of the manipulation process is to convert the hydrocarbons we discussed in the previous section into other organic chemicals that are more reactive more easily

The process of cracking involves the input of raw materials such as propane, butane and ethane into furnaces that heat up to 850 °C. This promotes a reaction which breaks the molecules down. The gas is then cooled to –140 °C to create solids which appear as pellets at the end of the process.

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27
Q

How many other atoms (hydrogen and carbon) are attached to each carbon in an ethane molecule?

A

Each carbon is only attached to three other atoms (rather than four like in CH4) so the molecule ends up being flat, normally called planar (rotate the 3D image until you can see this).

28
Q

What does the term unsaturated mean?

A

unsaturated compounds have less than the maximum number of hydrogen atoms possible. Polyunsaturated means that the molecules in the oil contain many C double bonds that make them reactive. This makes them useful for feedstock.

29
Q

What does saturated mean?

A

Compounds that are made of single bonds and maximum amount of hydrogen atoms

30
Q

What are polymers?

A

unsaturated hydrocarbons - plastics that come directly from crude oil.

31
Q

Define the term polymer?

A

refers to molecules that consist of very long chains of atoms

32
Q

Give some examples of biological polymers?

A

proteins, polysaccarides, DNA, RNA, wood, rubber, cotton, silk

33
Q

What is polythene?

A

It is the result of putting double bonds of ethane under intense pressure and heat to break the bonds to form a single bond of 2 ethane molecules attached. These polymers now turn in to monomers.

34
Q

What is the main use for polymers?

A

They make plastic bags.

35
Q

What is toxicology?

A

Traditionally toxicology was defined as the science of poisons, and a poison is colloquially described as a harmful substance. In fact, toxicology is the study of the adverse effects of chemicals on living organisms

36
Q

Can you think of any factors that may affect the toxicology of a chemical?

A

One that you might have thought of straightaway is the amount of chemical or size of the dosage

37
Q

What other factors that can affect the toxicity of a chemical?

A

Dosage is one of the most important factors in determining the toxicity of a chemical
the exposure route (inhalation, skin absorption, ingestion or injection)
the presence of other chemicals (for example, alcohol may enhance the effect of sedatives)
age (some chemicals are more toxic to infants than adults)
species differences in toxicity (for example, antibiotics are toxic to bacteria and mostly non-toxic to humans)

38
Q

Define the term dose?

A

Dose is defined as the amount of a chemical entering the body

39
Q

What are the important parameters for the dose of a substance?

A

How much, how often (frequency and duration) and how the dose is administered are important parameters. For example, if you are suffering from an ear infection, the doctor could give you the antibiotic Amoxicillin and its dose could be one 500 mg capsule three times a day for a period of five days by oral administration.

40
Q

What is a toxic agent?

A

In toxicology, a toxic agent is defined as anything that can produce an adverse biological effect (for example; inhibiting growth in plants or developing a medical condition in humans and animals). This may take the form of a chemical agent (for example, pesticides) or a physical agent (such as radiation).

41
Q

What is meant by the term response in regards to dosage of toxins?

A

The effect that a toxic agent has on a living organism is known as the response

42
Q

Why is the dose–response relationship is crucial in toxicology and what tests are carried out to achieve this?

A

The dose–response relationship is crucial in toxicology and this correlation is based on observed data from cell studies, animal testing and/or human clinical trials. For example, if humans are exposed to a single exposure of alcohol, the response will vary from no effect, to sleepiness, unconsciousness or even death depending on the amount ingested.

43
Q

What is the threshold dose level?

A

The point at which toxicity first appears is called the threshold dose level and from here toxicity increases with higher doses. In the response curve in Figure 1.16, the drug has no toxicity at a dose below 10 mg kg−1 whereas at 35 mg kg−1 100% of the individuals experience 100% toxic effects

44
Q

What is the median lethal dose LD50?

A

A common way of reporting results for toxicity is providing the toxic concentration that causes mortality in 50% of a population, known as the median lethal dose LD50.

45
Q

What is a cotyledon?

A

A cotyledon is the part of the embryo within the seed of a plant that provides some of the food reserve that the developing plant uses in its first few days of life after germination

46
Q

What two main forms do seeds come in?

A

Seeds come in two main forms: monocotyledonous (only one cotyledon) or dicotyledonous (two cotyledons)

47
Q

Seeds come in two main forms: monocotyledonous (only one cotyledon) or dicotyledonous (two cotyledons) Give an example of each one?

A

Grasses are an example of monocotyledonous plants and beans are a good example of plants with two cotyledons

48
Q

When the energy resource of the cotyledon becomes exhausted what does the germinating seed rely on?

A

seeds rely on energy from sunlight to allow them to produce food.

49
Q

As the seed germinates what emerges first?

A

The root or the radicle

50
Q

What is the name of the coat of a seed?

A

Testa

51
Q

What is the first stage of germination?

A

Its outer testa splits where the radicle emerges and is shown as a short white straight root that extends down from the broad bean seed.

52
Q

What is the second stage of germination?

A

the radicle grows down into the soil is shown as a white straight root extending down further

53
Q

After the radicle grows down in to the soil during germination, what happens next?

A

a developing shoot (plumule) pulling out from between the cotyledons as a folded white shoot above the white straight root, which continues to extend down further.

54
Q

What happens to the radicle once the root has already grown straight down?

A

shows lateral roots developing on the radicle as white straight short roots on the white straight main root

55
Q

What is the end stage of germination?

A

the plumule is above the soil shows the white shoot straightening and the leaves opening out above the white straight root, which now has more white lateral roots

56
Q

How can the radicle of a seed be easily identified?

A

When a seed begins to germinate the radicle can be identified easily as it is the first tissue that grows out of the seed, and also because it will show a tendency to grow downwards into the soil.

57
Q

Which are the crucial factors during germination?

A

Water, oxygen and a suitable temperature are required for germination

58
Q

What are the benefits of using fertilisers?

A

Fertilisers speed up germination and plant growth

59
Q

What is Hydrocarbons?

A

They are molecules containing hydrogen and carbon only.

60
Q

What are saturated hydrocarbons?

A

Saturated hydrocarbons contain the maximum amount of hydrocarbon, so have only single bonds

61
Q

What are unsaturated hydrocarbons?

A

unsaturated hydrocarbons contain carbon-carbon double bonds.

62
Q

What are isomers?

A

Isomers are molecules that have the same molecular formula but a different arrangement of atoms and bonds.

63
Q

Why do carbon atoms always forms four covalent bonds?

A

Carbon has four valence electrons and therefore always forms four covalent bonds.

64
Q

How can organic molecules be represented?

A

Organic molecules can be represented using structural, skeletal and abbreviated structural formulas

65
Q

What is usually the result of a median lethal dose?

A

Median lethal dose (LD50) is the concentration of a chemical that causes mortality in 50% of a populatio

66
Q

What is an organic compound?

A

They contain specific sets of atoms and bonds, Terms like ‘protein’, ‘carbohydrate’ and ‘fat’ are words we use every day to describe our food. These are examples of organic compounds

Topic 9 - Can We Live A Chemical Free Life? (2 decks)

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