# 0.8 Reactions in aqueous solutions  (Page 5/10)

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## Non-electrolytes

A non-electrolyte is a material that does not increase the conductivity of water when dissolved in it. The substance goes into solution and becomes surrounded by water molecules, so that the molecules of the chemical become separated from each other. However, although the substance does dissolve, it is not changed in any way and no chemical bonds are broken. The change is a physical change . In the oxygen example below, the reaction is shown to be reversible because oxygen is only partially soluble in water and comes out of solution very easily.

${C}_{2}{H}_{5}\mathrm{OH}\left(l\right)\to {C}_{2}{H}_{5}\mathrm{OH}\left(\mathrm{aq}\right)$
${O}_{2}\left(g\right)⇌{O}_{2}\left(\mathrm{aq}\right)$

## Factors that affect the conductivity of water

The conductivity of water is therefore affected by the following factors:

• The type of substance that dissolves in water. Whether a material is a strong electrolyte (e.g. potassium nitrate, ${\mathrm{KNO}}_{3}$ ), a weak electrolyte (e.g. acetate, ${\mathrm{CH}}_{3}\mathrm{COOH}$ ) or a non-electrolyte (e.g. sugar, alcohol, oil) will affect the conductivity of water because the concentration of ions in solution will be different in each case.
• The concentration of ions in solution. The higher the concentration of ions in solution, the higher its conductivity will be.
• Temperature. The warmer the solution, the higher the solubility of the material being dissolved and therefore the higher the conductivity as well.

## Aim:

To investigate the electrical conductivities of different substances and solutions.

## Apparatus:

Solid salt ( $\mathrm{NaCl}$ ) crystals; different liquids such as distilled water, tap water, seawater, benzene and alcohol; solutions of salts e.g. $\mathrm{NaCl}$ , $\mathrm{KBr}$ ; a solution of an acid (e.g. $\mathrm{HCl}$ ) and a solution of a base (e.g. $\mathrm{NaOH}$ ); torch cells; ammeter; conducting wire, crocodile clips and 2 carbon rods.

## Method:

Set up the experiment by connecting the circuit as shown in the diagram below. In the diagram, 'X' represents the substance or solution that you will be testing. When you are using the solid crystals, the crocodile clips can be attached directly to each end of the crystal. When you are using solutions, two carbon rods are placed into the liquid and the clips are attached to each of the rods. In each case, complete the circuit and allow the current to flow for about 30 seconds. Observe whether the ammeter shows a reading.

## Results:

Record your observations in a table similar to the one below:
 Test substance Ammeter reading

What do you notice? Can you explain these observations?

Remember that for electricity to flow, there needs to be a movement of charged particles e.g. ions. With the solid $\mathrm{NaCl}$ crystals, there was no flow of electricity recorded on the ammeter. Although the solid is made up of ions, they are held together very tightly within the crystal lattice and therefore no current will flow. Distilled water, benzene and alcohol also don't conduct a current because they are covalent compounds and therefore do not contain ions.

The ammeter should have recorded a current when the salt solutions and the acid and base solutions were connected in the circuit. In solution, salts dissociate into their ions, so that these are free to move in the solution. Acids and bases behave in a similar way and dissociate to form hydronium and oxonium ions. Look at the following examples:

$\mathrm{KBr}\to {\mathrm{K}}^{+}+{\mathrm{Br}}^{-}$
$\mathrm{NaCl}\to {\mathrm{Na}}^{+}+{\mathrm{Cl}}^{-}$
$\mathrm{HCl}+{\mathrm{H}}_{2}\mathrm{O}\to {\mathrm{H}}_{3}{\mathrm{O}}^{+}+{\mathrm{Cl}}^{-}$
$\mathrm{NaOH}\to {\mathrm{Na}}^{+}+{\mathrm{OH}}^{-}$

#### Questions & Answers

what's economic development and growth
what do you understand by Ceteris Paribus?
explain the uses of microeconomics
uses of microeconomics
Nikita
Adam Smith's definition of economics
what is economic deficit
this is a situation whereby a nation's outcome or available resources are not enough to the people thereby causing scarcity
Ariel
prices of Quality demanded is equal to Quality supplied
it's quantity demand and quantity supplied that's called equilibrium
Romy
no
NABUBOLO
they deal With prices
NABUBOLO
define the elasticity
NABUBOLO
explain different types of elasticity
NABUBOLO
oops 😬 you are right you talk about quality I tell about quantity
Romy
elasticity is the measurement of the percentage change of one economic variable in response to a change in another
Romy
Cross Elasticity of Demand (XED) Income Elasticity of Demand (YED) Price Elasticity of Supply (PES)
Romy
anything else?
Romy
I need to know everything about theory of consumer behavior
Grace
How does one analyze a market where both demand and supply shift?
That's equilibrium market
Ramon
but an equlibrum can appear twice on the same market... both in Movement along the Demand/supply curve of shift in the Curve
Gabriel
I Mean on the same curve..
Gabriel
how can consumer surplus be calculated
Franklyn
How can we analyze the effect on demand or supply if multiple factors are changing at the same time—say price rises and income falls?
because of fall of income, less will be demanded and much will be supply as a result of price rises. Rise in price always motivate new supplier to enter into the system. But it only possible in the short run
Kweku
yeah.. I think Ceteris Paribus is applied in this case
Gabriel
that is the law of Demand is Inversely related to the law of Supply... so that mean a positive change in demand may produce a negative return to supply I think.
Gabriel
what are the difference between Wants and Needs
When the price is above the equilibrium, explain how market forces move the market price to equilibrium. Do the same when the price is below the equilibrium.
Gabriel
economic problems
Manishankar
Gabriel
I don't know this is my question
Manishankar
no it was a mistake...😂😂 can you explain how Wants and needs differs 😌
Gabriel
wants is what human desire but might not need them, human want are mostly articles of ostentatious while need is what human must get to live e.g inferior goods
Ramon
what's equilibrium price
james
equilibrium prices is a situation whereby the price of goods supplied equates to the demand
Ariel
this whereby the prices of quality demanded is equivalent to quality demanded
NABUBOLO
wants are numerous desire man that man can do without if not purchased e.g. cosmetic while need are desires that you cannot do without e.g. food
Franklyn
equilibrium price is that level of output were quantity demanded is equal to quantity supplied
Arthur
what are the importance of studying economics
To know if the country is growing or not through the country's GDP
Ariel
to manage our resources
TOBI
compare base years GDP and the current years GDP
james
To tell whether a country is growing there are many factors to be considered not necessarily only the GDP due to weaknesses of GDP approach
james
What is the law of demand
price increase demand decrease...price decrease demand increase
Mujahid
ıf the price increase the demand decrease and if the demand increase the price decrease
MUBARAK
all other things being equal, an increase in demand causes a decrease in supply and vice versa
SETHUAH
yah
Johnson
how is the economy of usa now
Johnson
What is demand
Demand is the quantity of goods and services a consumer is willing and able to purchase at various prices over a given period of time.
Yaw
yea
SETHUAH
Okay congratulations I'll join you guys later .
Aj
yes
MUBARAK
demand is the quantity and quality of goods and services a consumer is willingly and able to purchase at a particular price over a given period of time.
TOBI
calculate elasticity of income exercises
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