# 0.8 Reactions in aqueous solutions  (Page 4/10)

 Page 4 / 10

Acid rain can have a very damaging effect on the environment. In rivers, dams and lakes, increased acidity can mean that some species of animals and plants will not survive. Acid rain can also degrade soil minerals, producing metal ions that are washed into water systems. Some of these ions may be toxic e.g. ${\mathrm{Al}}^{3+}$ . From an economic perspective, altered soil pH can drastically affect agricultural productivity.

Acid rain can also affect buildings and monuments, many of which are made from marble and limestone. A chemical reaction takes place between ${\mathrm{CaCO}}_{3}$ (limestone) and sulphuric acid to produce aqueous ions which can be easily washed away. The same reaction can occur in the lithosphere where limestone rocks are present e.g. limestone caves can be eroded by acidic rainwater.

${\mathrm{H}}_{2}{\mathrm{SO}}_{4}+{\mathrm{CaCO}}_{3}\to {\mathrm{CaSO}}_{4}·\mathrm{H}{}_{2}\mathrm{O}+{\mathrm{CO}}_{2}$

## Investigation : acid rain

You are going to test the effect of 'acid rain' on a number of substances.

## Materials needed:

samples of chalk, marble, zinc, iron, lead, dilute sulphuric acid, test tubes, beaker, glass dropper

## Method:

1. Place a small sample of each of the following substances in a separate test tube: chalk, marble, zinc, iron and lead
2. To each test tube, add a few drops of dilute sulphuric acid.
3. Observe what happens and record your results.

## Discussion questions:

• In which of the test tubes did reactions take place? What happened to the sample substances?
• What do your results tell you about the effect that acid rain could have on each of the following: buildings, soils, rocks and geology, water ecosystems?
• What precautions could be taken to reduce the potential impact of acid rain?

## Electrolytes, ionisation and conductivity

Conductivity in aqueous solutions, is a measure of the ability of water to conduct an electric current. The more ions there are in the solution, the higher its conductivity.

Conductivity
Conductivity is a measure of a solution's ability to conduct an electric current.

## Electrolytes

An electrolyte is a material that increases the conductivity of water when dissolved in it. Electrolytes can be further divided into strong electrolytes and weak electrolytes .

Electrolyte
An electrolyte is a substance that contains free ions and behaves as an electrically conductive medium. Because they generally consist of ions in solution, electrolytes are also known as ionic solutions.
1. Strong electrolytes A strong electrolyte is a material that ionises completely when it is dissolved in water:
$\mathrm{AB \left(s, l, g\right)}\to {\mathrm{A}}^{+}\mathrm{\left(aq\right)}+{\mathrm{B}}^{-}\mathrm{\left(aq\right)}$
This is a chemical change because the original compound has been split into its component ions and bonds have been broken. In a strong electrolyte, we say that the extent of ionisation is high. In other words, the original material dissociates completely so that there is a high concentration of ions in the solution. An example is a solution of potassium nitrate:
${\mathrm{KNO}}_{3}\mathrm{\left(s\right)}\to {\mathrm{K}}^{+}\mathrm{\left(aq\right)}+{\mathrm{NO}}_{3}^{-}\mathrm{\left(aq\right)}$
2. Weak electrolytes A weak electrolyte is a material that goes into solution and will be surrounded by water molecules when it is added to water. However, not all of the molecules will dissociate into ions. The extent of ionisation of a weak electrolyte is low and therefore the concentration of ions in the solution is also low.
$AB\left(s,l,g\right)\to AB\left(aq\right)⇌{A}^{+}\left(\mathrm{aq}\right)+{B}^{-}\left(\mathrm{aq}\right)$
The following example shows that in the final solution of a weak electrolyte, some of the original compound plus some dissolved ions are present.
${C}_{2}{H}_{3}{O}_{2}H\left(l\right)\to {C}_{2}{H}_{3}{O}_{2}H⇌{C}_{2}{H}_{3}{O}_{2}^{-}\left(\mathrm{aq}\right)+{H}^{+}\left(\mathrm{aq}\right)$

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
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sciencedirect big data base
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Introduction about quantum dots in nanotechnology
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absolutely yes
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it is a goid question and i want to know the answer as well
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for teaching engĺish at school how nano technology help us
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fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
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what is the actual application of fullerenes nowadays?
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what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
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is Bucky paper clear?
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carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
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Do you know which machine is used to that process?
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how to fabricate graphene ink ?
for screen printed electrodes ?
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What is lattice structure?
of graphene you mean?
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or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
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what is biological synthesis of nanoparticles
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Good
What makes metals better to use as wires than non-metals? (please link to bonding type)??? HELP