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- Chemistry grade 10 [caps]
- Chemistry grade 10 [caps]
- States of matter and the kinetic
The properties of matter
Let us now look at what we have learned about chemical
bonds, intermolecular forces and the kinetic theory of matter, and see whetherthis can help us to understand some of the macroscopic properties of materials.
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Melting point
Melting point
- The temperature at which a
solid changes
its phase or state to become a
liquid . The
process is called melting and the reverse process (change in phase from liquidto solid) is called
freezing .
In order for a solid to melt, the energy of the particles
must increase enough to overcome the bonds that are holding the particlestogether. It makes sense then that a solid which is held together by strong
bonds will have a
higher melting point
than one where the bonds are weak, because more energy (heat) is needed to breakthe bonds. In the examples we have looked at metals, ionic solids and some
atomic lattices (e.g. diamond) have high melting points, whereas the meltingpoints for molecular solids and other atomic lattices (e.g. graphite) are much
lower. Generally, the intermolecular forces between molecular solids are
weaker than those between ionic and
metallic solids.
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Boiling point
Boiling point
- The temperature at which a
liquid changes
its phase to become a
gas . The process is
called evaporation and the reverse process is called condensation
When the temperature of a liquid increases, the average
kinetic energy of the particles also increases and they are able to overcomethe bonding forces that are holding them in the liquid. When boiling point is
reached,
evaporation takes place and some
particles in the liquid become a gas. In other words, the energy of theparticles is too great for them to be held in a liquid anymore. The stronger the
bonds within a liquid, the higher the boiling point needs to be in order tobreak these bonds. Metallic and ionic compounds have high boiling points while
the boiling point for molecular liquids is lower.The data in
[link] below may help you to understand some of
the concepts we have explained. Not all of the substances in the table aresolids at room temperature, so for now, let's just focus on the
boiling points for each of these substances. What do
you notice?
Substance |
Melting
point (
) |
Boiling point (
) |
Ethanol (
) |
-
114,3 |
78,4 |
Water |
0 |
100 |
Mercury |
-38,83 |
356,73 |
Sodium chloride |
801 |
1465 |
The melting and boiling
points for a number of substances
You will have seen that substances such as ethanol, with relatively weak
intermolecular forces, have the lowest boiling point, while substances withstronger intermolecular forces such as sodium chloride and mercury, must be
heated much more if the particles are to have enough energy to overcome theforces that are holding them together in the liquid. See the
section below for a further exercise on boiling point.
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Density and viscosity
Density and viscosity is not in CAPS - Included for Completeness
Density
- Density is a measure of the mass of a substance per
unit volume.
The density of a solid is generally higher than that of a liquid
because the particles are held much more closely together and therefore thereare more particles packed together in a particular volume. In other words, there
is a greater mass of the substance in a particular volume. In general, densityincreases as the strength of the intermolecular forces increases.
Viscosity
- Viscosity is a measure of how resistant a liquid is to
flowing (in other words, how easy it is to pour the liquid from one container toanother).
Viscosity is also sometimes described as the 'thickness' of a fluid.
Think for example of syrup and how slowly it pours from one container intoanother. Now compare this to how easy it is to pour water. The viscosity of
syrup is greater than the viscosity of water. Once again, the stronger theintermolecular forces in the liquid, the greater its viscosity.
Questions & Answers
differentiate between demand and supply
giving examples
differentiated between demand and supply using examples
Lambiv
how is the graph works?I don't fully understand
hi guys good evening to all
Lambiv
In economics, a perfect market refers to a theoretical construct where all participants have perfect information, goods are homogenous, there are no barriers to entry or exit, and prices are determined solely by supply and demand. It's an idealized model used for analysis,
Ezea
other things being equal
AI-Robot
When MP₁ becomes negative, TP start to decline.
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of lab
Kelo
Extuples Suppose that the short-run production function of certain cut-flower firm is given by: Q=4KL-0.6K2 - 0.112 •
Where is quantity of cut flower produced, I is labour input and K is fixed capital input (K-5). Determine the average product of labour (APL) and marginal product of labour (MPL)
Kelo
Can I ask you other question?
Shukri
What is different between quantity demand and demand?
Quantity demanded refers to the specific amount of a good or service that consumers are willing and able to purchase at a give price and within a specific time period. Demand, on the other hand, is a broader concept that encompasses the entire relationship between price and quantity demanded
Ezea
how do you save a country economic situation when it's falling apart
what is the difference between economic growth and development
Economic growth as an increase in the production and consumption of goods and services within an economy.but
Economic development as a broader concept that encompasses not only economic growth but also social & human well being.
Shukri
production function means
Jabir
What do you think is more important to focus on when considering inequality ?
any question about economics?
sir...I just want to ask one question... Define the term contract curve? if you are free please help me to find this answer 🙏
Asui
it is a curve that we get after connecting the pareto optimal combinations of two consumers after their mutually beneficial trade offs
Awais
thank you so much 👍 sir
Asui
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities, where neither p
Cornelius
In economics, the contract curve refers to the set of points in an Edgeworth box diagram where both parties involved in a trade cannot be made better off without making one of them worse off. It represents the Pareto efficient allocations of goods between two individuals or entities,
Cornelius
Suppose a consumer consuming two commodities X and Y has
The following utility function u=X0.4 Y0.6. If the price of the X and Y are 2 and 3 respectively and income Constraint is birr 50.
A,Calculate quantities of x and y which maximize utility.
B,Calculate value of Lagrange multiplier.
C,Calculate quantities of X and Y consumed with a given price.
D,alculate optimum level of output .
the market for lemon has 10 potential consumers, each having an individual demand curve p=101-10Qi, where p is price in dollar's per cup and Qi is the number of cups demanded per week by the i th consumer.Find the market demand curve using algebra. Draw an individual demand curve and the market dema
suppose the production function is given by ( L, K)=L¼K¾.assuming capital is fixed find APL and MPL. consider the following short run production function:Q=6L²-0.4L³ a) find the value of L that maximizes output b)find the value of L that maximizes marginal product
Abdureman
What is the difference between perfect competition and monopolistic competition?
Mohammed
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Source:
OpenStax, Chemistry grade 10 [caps]. OpenStax CNX. Jun 13, 2011 Download for free at http://cnx.org/content/col11303/1.4
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