Qualitative Analysis to identify ions!

By Emma Khazzam!

11 grade, Chemistry!

May 13, 2014!

!What is qualitative analysis? Qualitative analysis is when one measures the quality of

a sample rather then its quantity. Qualitative chemical analysis helps us identify an

element or grouping of elements present in a sample. It is an analysis that identifies

elements, substances, ions and compounds of a sample and there are many different

ways to identify the ions found in a substance using qualitative analysis. Three

examples are the flame test, looking at the colour of the solution, and looking at the

formation of a precipitate.!

!The first qualitative analysis to identify ions is the flame test. The flame test is a

qualitative analysis that allows us to identify different metal ions in a solution. When

metal ions are heated in a flame, they turn a unique colour, and when examining the

colour of the flame, one can try to identify the ions present in the solution. For example,

when lithium ions are heated they turn crimson red, but when potassium ions are

heated they turn lavender. One problem with flame tests is that they are very sensitive,

so when conducting an experiment, it is advised to only use tiny samples to increase

the test’s accuracy. An extremely useful tool when conducting flame tests is the Bunsen

burner. The Bunsen burner was named for Robert Wilhelm Eberhard Bunsen

(1811-1899), a German chemist who contributed to its invention only in a minor way. !

The Bunsen burner produces a clean, hot flame and is used along with a wire loop

(usually platinum or an alloy of nickel and chromium) to perform flame tests. When

using aqueous solutions, one must simply dip the wire into the solution and then place it

into the flame. When using solid solutions, one must first combine the solution with

hydrochloric acid or nitric acid, then add it to the wire and finally place it into the flame.

The electrons of the solution absorb the energy of the flame and then re-emit that

energy as visible light, causing the flame to change colour. Because of the different

arrangements of electrons for each ion, the colours of the flames will be different, which

caused Bunsen to discover cerium and rubidium. Flame tests are a useful type of

qualitative analysis but they are very sensitive and can be inaccurate.!

!The second qualitative analysis that is used to identify ions, is by observing the

colours of the ions in an aqueous solution. Aqueous solutions that have compounds of

certain cations, positively charged ions, and anions, negatively charged ions, have

unique colours. The colours of these aqueous solutions can help us identify some of the

ions in a sample. For example, aqueous solutions that contain chromium (III) cations

are green, whereas if they contain chromium (II) cations they are blue. If an aqueous

solution is purple, then it might contains permanganate anions, but if it is yellow then it

may contain chromate anions.!

!The last qualitative analysis to identify ions is by the formation of precipitation

reactions. By adding a known reactant to an unknown solution we can find the unknown

ion by observing whether a precipitate forms. Precipitates can form when two soluble (a

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substance that is able to dissolve) salts react to form one or more insoluble (a

substance that is unable to dissolve) products. When the insoluble product separates

from the liquid, it is called a precipitate. One can use solubility guidelines (rules that help

us find which elements are soluble and which are not) to deduce the unknown ions that

are present in the solution. To find the ions in a solution, one must remove all the ions

each time a precipitate forms. After the precipitate is filtered out, one must add other

reactants to the filtrate (filtered solution). The colour of the solution after each reaction

can help identify the ions present. For example, when copper sulphate and sodium

hydroxide react, a product is a blue precipitate of copper hydroxide.!

!Qualitative analysis helps us identify different components in a sample using data

that cannot be measured, such as texture, smell, taste, appearance, and colour. We

perform qualitative chemical analysis by observing the colour of flames in flame tests,

the colour of aqueous solutions, or by the coloration of a solution after a precipitation

reaction. By doing this we can try to identify certain ions present in solutions.

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Harmful substances in water from natural sources!

By Emma Khazzam!

11 grade, Chemistry!

May 13, 2014!

!Water on earth cycles; from the land to the sky and back again. As natural, fresh

water rises into the sky, turning into rain and snow, the water mixes with the gases in

the atmosphere and turns acidic. When these precipitants fall from the sky down to

earth, the acidic water reacts with the basic elements of the soil. These elements, such

as arsenic ions, fluoride ions, calcium ions and magnesium ions leach into the ground

water and are harmful to humans.!

!As the natural water cycle reaches the atmosphere, carbon dioxide gases dissolve

into the rain water or snow, and produce diluted carbonic acid. When the water falls

down to earth, the acid reacts with different elements and ions, such as calcium,

magnesium, iron (III), iron (II), carbonate, and sulphate. Some of these ions, when the

concentration is high enough, are harmful to human health. For example, arsenic ions

are found naturally in the ground water of river deltas. In Canada, regulations have been

placed that say that arsenic has to be less than 5 ppb (parts per billion) for it to be safe

to sell and consume. But in Bangladesh, which is a delta land, the drinking water for

more than 35 million people has more than 50 ppb of arsenic! Long-term exposure to

arsenic has been linked to cancer of the bladder, lungs, skin, kidney, nasal passages,

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liver, and prostate. Other effect can include thickening and discolouration of the skin,

nausea, stomach pain, diarrhoea, vomiting, partial paralysis and blindness.!

!Another element that is found in drinking water is fluoride, which has both risks and

benefits. One of the risks of fluoride in drinking water is dental fluorosis, which causes

teeth to stain if they are in contact with too much fluoride. Yet, if the concentration less

than 1 ppm (parts per million), the fluoride replaces the cations of the teeth enamel and

leaves healthier teeth, without staining. This causes many municipalities add fluoride

ions to drinking water to prevent tooth decay, but there are many organizations, such as

the Fluoride Action Network, that are trying to eliminate fluoridation. Some of their

arguments state that fluoride is unethical, that its dose cannot be controlled, and that

fluoridated water can be consumed by everyone regardless of their age, health or

vulnerability.!

!Hard water, which is usually caused by calcium or magnesium ions, can be very

problematic. Hard water is water that contains a relatively high concentration of ions and

creates insoluble compounds with soap (salt of a fatty acid). Soft water is the opposite

of hard water; it is water with a small concentration of ions that form insoluble

compounds with soap. An insoluble compound is a substance that is incapable of being

dissolved and a soluble compound is the opposite; they are substances that are

capable of being dissolved. When it rains, the carbonic acid that is found in rainwater

reacts with calcium or magnesium ions that are found in rocks. These ions enter the

water solution and turn it into hard water. One way of finding out if your water is hard is

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if it has difficulty forming a lather with soap, and instead forms a sticky soap curd. These

soap curds cause clothes to look dingy and feel harsh and scratchy, they leave films on

dishes, bathtubs, showers and all other water fixtures, and they prevent the removal of

soil and bacteria from skin, which leads to irritation. !

!Another way of finding out if water is hard is by looking for the formation of lime

scales (calcium carbonate deposits), a chalky, hard substance that builds up in water

pipes, kettles, and humidifiers. Lime scale reduces the water flow in taps and pipe,

stains bathtubs and sinks, and prevents the heat to transfer in kettles. Lucky, there is a

simple way of fixing this problem. By using white vinegar (acetic acid), a simple house

product, one can easily remove the stains caused by lime scale. This acid reacts with

calcium and magnesium carbonates to form soluble compounds, breaking down the

calcium carbonate. !

!There are often elements that are naturally found in water that are potentially

dangerous to humans and have negative impacts on our drinking water. Arsenic ions,

fluoride ions, calcium ions and magnesium ions are only a short list of substances found

in nature that can be harmful to humans. Other substances include mercury, uranium,

and bromine.!

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Harmful pollutants that enter drinking water from human

activities!

By Emma Khazzam!

11 grade, Chemistry!

May 13, 2014!

!Seventy one percent of the Earth’s surface is made up of water. Ninety seven point

five of this water is contained within the oceans, leaving only the remaining 2.5% to be

freshwater. This 2.5% is extremely precious to human beings; we use fresh water for

everything! Unfortunately, there are many pollutants from human activities that affect our

water sources, including manufacturing, farming, transportation, and garbage disposal.

All of these examples contribute to the pollution of water systems. Some of the main

human pollutants are lead, mercury, nitrate, airborne chemicals and chemicals from

plastics.!

!These are pollutants classified as either point source or non-point source. Point

source pollutants are pollutants that come from a single source in a specific location. A

wrecked tanker that is leaking oil or a pulp mill that throws away its toxic effluent into a

river are examples of point source pollutants. Non-point sources do not come from a

single source and have an easily defined location. They can be from sources that are

spread out, such as pesticides and fertilizers on farmland, or can be a combination of a

large amount of small point sources, such as the exhaust from cars. Non-point

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pollutants and the collective effects of many small point sources can be a serious

problem for water sources. Though there are different regulations that try to reduce their

effect, pollutants such as lead, mercury, nitrate, airborne chemicals and chemicals from

plastics remain a problem.!

!The exposure to lead can lead to many medical problems, including abdominal pain,

kidney failure, nerve damage, and different brain disorders. The lead in fresh water is

rarely from natural sources, and is mostly released into the environment from old water

pipes, industrial recesses, ore smelting, the manufacture and recycling of car batteries,

and the preparation of some types of plastic. Fortunately, over the last 30 years, the

concentration in air and water of lead has significantly decreased, sometimes by more

than 75 percent! This decrease in lead levels is most likely due to the worldwide effort to

stop the use of leaded gasoline in on-road vehicle.!

!Another harmful pollutant is mercury. This element is highly toxic and greatly affects

the human body. It can affect the central nervous system, and cause tumours, irritability,

insomnia, numbness, tunnel vision, liver damage, and kidney damage. Mercury can be

emitted both naturally and by humans. Volcanoes are an extremely harmful natural

mercury pollutant and they may be responsible for about one half of all mercury in the

atmosphere. These toxins are equally emitted from human sources such as coal-fired

power plants, gold mines, cement plants and smelting for non-ferrous metals (metal that

do not contain iron). !

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Nitrate pollution is problematic both for wildlife and humans. The greatest sources of

nitrate pollutants in Canada come from livestock waste and nitrogen-based fertilizers.

Nitrogen-based fertilizers increase the crop yield, but when the fertilizer leaches into the

lakes and rivers, the growth of aquatic plants, including algae, increases. When the

plants die and decompose, the amount of dissolved oxygen in the water subsides,

which causes a stress on the fish because they have less oxygen to breathe. The

decrease in oxygen causes the aquatic wildlife to die. Nitrate ions can equally affect

humans. When these ions are present in drinking water, in a high concentration, they

can be harmful to babies. The digestive system of infants converts the nitrate ions to

nitrite ions. The nitrite ions bond with hemoglobin, the iron-containing oxygen-

transporting protein in the red blood cells, which decreases the amount of hemoglobin

left to bond with oxygen. This causes the body’s tissues to be starved of oxygen, which

causes babies to turn blue. This condition is called blue-baby syndrome, but as the

youth grows and the amount of acid in the stomach increases, the body inhibits the

conversion from nitrate to nitrite.!

!There are many airborne pollutants that contribute to water pollution. The sources of

these pollutants include motor vehicles, refineries, and factories that release gases such

as carbon dioxide gas, sulphur dioxide and nitrogen oxide gases. When these non-

metalic oxides dissolve in rainwater they become acid rain, and the more acid rain that

there is, the more compounds get dissolved into it from soil and rocks. For example,

acid rain leaches aluminium ions from the soil into ground water and surface water. This

element is harmful for fish because the ions obstruct the path of oxygen from the water

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into the gills. When people are exposed to toxic air pollutants, at sufficient

concentrations, they may have an increased chance of getting cancer or other serious

health problems, including neurological, reproductive, developmental, respiratory

problems and damage to the immune system. !

!Have you ever drunken water from a plastic bottle and found that it tasted a bit like

plastic? Substances from unexpected sources, like plastic water bottles, equally affect

our drinking water. Different containers, such as water bottles, are made using hard,

clear plastics called polycarbonates. These polycarbonates are made with BPA or

bisphenol A, which is a carbon-based synthetic compound. This chemical can leach into

the water from the bottle. BPA triggers biological changes, that are linked to breast

cancer and heart disease. Countries are starting to place regulations to control the

amount of BPA that we digest. Canada was the 1st country to ban BPA from baby

bottles, but it is still used to make kitchen containers and the linings of cans. BPA and

other chemicals can be leached into the environment.!

!Pollution from human sources is a serious problem, especially because the earth’s

water sources are limited. Fortunately, there are ways to help keep our water clean,

safe and healthy. By taking great care not to overuse pesticides and fertilizers, by not

throwing away litter into rivers, lakes or oceans, by using environmental house products,

by conserving water, and by being careful about what you throw down your sink or toilet

(not throwing out paints, oils or other forms of litter down the drain), you can help keep

one of the earth’s most amazing resource clean.

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Treating water hardness!

By Emma Khazzam!

11 grade, Chemistry!

May 13, 2014!

!Have you ever noticed mineral deposits on your cooking dishes or that your soap

does not lather but rather leaves insoluble soap scum in your bathtub? This is probably

not because of bad housekeeping, but is rather the sign of hard water. What is water

hardness? Hard water is water with a high concentration of ions that form insoluble

compound with soap. It contains cations with a charge of +2, usually calcium and

magnesium ions. Though they do not usually pose health threats, deposits of hard

water can be unsuitable for many uses. Luckily, there are ways of treating water

hardness by softening the water.!

!There are two types of hardness; temporary water hardness and permanent water

hardness. Temporary hardness is hard water that can be removed by boiling water, by

driving the ions out of the solution though heat. An example of temporary hardness is

calcium carbonates. When calcium reacts with rainwater that contains dissolved carbon

dioxide, it creates calcium carbonates. Yet, this reaction can be reversed by boiling the

water; the boiling drives most of the carbon dioxide out. !

!Permanent hardness is water hardness that that cannot be removed by boiling, but

can be removed by other methods. One example for permanent hardness is calcium !

sulphate, that can not be removed by boiling, but has to be removed chemically. The

least expensive method of doing this is by using hydrated sodium carbonate or washing

soda. One problem with using washing soda is that it makes the water basic. A way to

avoid making the water basic is by using ion-exchanging water softeners.!

!Ion-exchange water softeners exchange the ions that cause hard water. These

softeners trade ions such as calcium, for something else, usually sodium ions, to create

soft water (water with a small concentration of ions that form insoluble compound with

soap). The heart of a water softener is a mineral tank which is filled with small

polystyrene beads, made from resin or zeolite (microporous crystalline solids that

generally contain silicon, aluminium and oxygen). These beads carry a negative charge

while calcium and magnesium both carry positive charges. Because they are oppositely

charged, the ions cling to the beads as the hard water passes though the tank. Sodium

ions, which are attached to the beads, also have positive charges, but their charges are

not as strong as calcium and magnesium ions. When the solution is put thought the

tank, the calcium and magnesium ions move to the beads, replacing sodium ions. Once

the beads are saturated with the calcium and magnesium ions, the water enters a three-

phase regenerating cycle. Firstly, there is the backwash phase which reverses the flow

of the water so that the dirt is flushed out of the tank. Secondly, there is the recharge

phase, which takes the sodium-rich salt solution out of the brine tank and through the

mineral tank. The final phase is to flush the mineral tank of excess brine and refill the

brine tanks.!

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Though water softening is extremely beneficial, there are some problems. The

sodium, that remains in softened water may be troublesome for those who have

sodium-restricted diets. Treated water has a slightly salty taste, a taste that some

people wish to avoid. In these cases, one can install a separate water dispenser that

bypasses the softener or use potassium chloride instead of salt, but the cost would

increase about three to four times.

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!Drinking water standards in Canada!

By Emma Khazzam!

11 grade, Chemistry!

May 13, 2014!

!When drinking water, one must have certain standards. It should be clean,

colourless, odourless, and cannot have a bad taste. Water should not contain any

disease-causing or unsafe particles such as E coli, or coliform bacteria. Unfortunately,

water found in nature can never meet these standards. As water in nature runs its

course, it picks up bits and pieces such as vegetation, fertilizers, minerals etc. Though

most of these particles might be harmless, some of the may pose a health risk. To

address this risk, governments have developed standards to protect the health of its

society, especially the most vulnerable members such as the elderly and children.

Health Canada has worked with both provincial and territorial governments to help

develop these guidelines. The Guidelines for Canadian Drinking Water Quality deal with

microbiological, chemical, and radiological contaminants.!

!The most significant risks to people’s health from drinking water comes from the

microscopic organisms that can be found in water. This includes disease-causing

bacteria, protozoa and viruses. Because the associated health effects of these

organisms can be very severe, both in the short and long term, the guidelines have to

be very strict. There are also chemical and radiological substances that may be found

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in drinking water supplies, though they are usually only a health concern if they are

present above set guideline levels, including MAC and IMAC.!

!Ontario drinking water standards apply specifically to the MAC, which means

Maximum Allowable Concentration, value of a substance. This is a drinking water

standard for substances that are known or suspected to affect human health when

above a certain concentration. They are not physical constants, but rather they are

values and standards that are set, usually by national bodies. The MAC values are set

to ensure the health and safety at the workplace and are defined and revised based on

reliable toxicological and medical evidence. Examples of MAC standards are that

drinking water cannot contain more than five coliform bacteria per 100 mL. Cadmium

(Cd2+), a chemical used in some types of batteries, has a maximum allowable

concentration of 0.005.!

!Yet MAC guidelines and standards are frequently adjusted. When scientists are doing

research, they might create a IMAC, with is a Interim Maximum Allowable

Concentration. IMACs are created when there is an insufficient amount of data for a

MAC. An example of an IMAC is dioxin and furan, which is the burning of waste,

especially plastics, has an interim maximum allowable concentration is 0.000 000 015

mg/L. These guidelines include AOs, aesthetic objectives. AOs are standards that

address the parameters that affect the consumer’s acceptance of drinking water, such

as taste, odour and colour, but they are not health hazards. An example of aesthetic

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objectives is that only 250 mg/L of chloride, which is used for water treatment, can be

used.!

Drinking water is essential to life, yet it is naturally exposed to pathogens and

chemical, physical and radiological contaminants. These organisms can affect human

health, both in the short-term and the long-term, and are known to contribute to a large

range of adverse health effects including cancer, neurological disorders, reproductive

problems, the disruption of the endocrine system, and gastrointestinal illnesses. For

these reasons, it is important that standards and guidelines are set to protect the human

population. Standards ensure that our water is safe, clean, tasty and healthy. !

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