Dissolve some calcium hydroxide (lime used in betel chewing) in water. When you filter this solution with a filter paper you get lime water. It is a colourless solution. A white layer could be seen if the lime water solution is exposed to air.
Thursday, December 16, 2010
SENT CARBON DIOXIDE INTO LIME WATER.
When carbon dioxide gas is sent to lime water, calcium hydroxide in lime water reacts with the gas giving white calcium carbonate which is insoluble. The solution becomes milky due to this. If we pass carbon dioxide continuously, calcium bicarbonate which is soluble is formed. The the solution become clear again.
PROPERTIES OF CARBON DIOXIDE
CARBON DIOXIDE GAS IS,
1.IS colour less,
2.Has specific odour,
3.Is heavier than air,
4.Is a non – supporter of combustion,
5.Turns lime water milky,
6.Have fire exitinguishing properties.
IDENTIFICATION OF CARBON DIOXIDE
Introduce a small amount of lime water into a jar with carbon dioxide prepared in the page number 19 and shake it. Clear lime water turns milky. This can be used as a test for carbon dioxide.
COLLECTION OF CARBON DIOXIDE GAS
When collecting carbon dioxide the gas jar is kept upwards and the delivery tube is placed in it. Here air is displaced upwards the gas gets collected. This method of collecting gases is called the “upward displacement of air”- gases denser than air can be collected by this method. We can cover the gas jar with gas jar lids and can be used for further activities.
USES OF CARBONDIOXIDE
This has which is about 0.03% of the atmosphere is of great use. Some instances are given below.
1.When soda and sweet drinks are produced, this gas is dissolved in them under high pressure.
2.For fire extinguishing purposes.
3.To make dry ice as a cooling agent and producing artificial rain (dry ice is solid carbondioxide produced by solidifying carbondioxide under high pressure).
THE METHOD OF BALlOON FILLED WITH HYDROGEN
Bory the bottle about 2/3rd in the soil. Put aluminum pieces and caustic soda into it. Add hot water to the bottle. Fix the balloon to the bottle. The balloon will be filled with hydrogen. Tie the mouth of the balloon and remove it from the bottle. Release the balloon in to the atmosphere. You would be surprised to see the balloon rising up.
PROPERTIES OF HYDROGEN GAS
Hydrogen gas is :-
1.Is colourless,
2.Has no specific odour,
3.Is slightly soluble in water,
4.Is inflamable,
5.Is ligterthan air(less dense)
1.Is colourless,
2.Has no specific odour,
3.Is slightly soluble in water,
4.Is inflamable,
5.Is ligterthan air(less dense)
ITENDYFYING THE HYDROGEN GAS
Observe the colour and odour of a hydrogen sample you collected.
Close one boiling tube filled with hydrogen with a glass plate and hold its mouth upwards. Then insert a lighted taber into it as you open the lid.
The gas burns with a ‘pop’ sound. This shows that hydrogen is an in flammable gas.
COLLECTION OF HYDROGEN
When hydrogen gas is collected in the boiling tube, the air inside the tube is displaced downwards. This method of collecting gases is called the the DOWNWARDS DISPLACEMENT OF AIR. Light gases which are less heavier than air are collected by this method.
Hydrogen does not dissolve much in water. Therefore it can be collected over water too.
USES OF HYDROGEN
The Sun
The Sun outshines everything else in the sky. Hydrogen makes up the bulk of the Sun and provides fuel for the nuclear reactions that make the Sun shine.
Horsehead Nebula
Stars are born from nebulas like the Horsehead Nebula, which is more than 1,000 light-years from the Earth. The nebula consists mainly of hydrogen gas. Hydrogen is the most common element in the universe.
PROPERTIES OF OXYGEN
OXYGEN GAS IS,
1.COLOUR LESS
2.NO SPECIFIC ODOUR
3.SLIGHTLY SOLUABLE IN WATER
4.A SUPORTER OF COMBUSTION
COLLECTION and IDENTYFICATION METHOD OF OXYGEN
COLLECTION METHOD OF OXYGEN
WHEN OXYGEN GAS COLLECT IN THE GAS JARS THE WATER IN IT MOVES DOWN AND GETS COLLECTED IN THE TROUGH. THIS METHOD IS NAMED AS COLLECTING GAS BY THE DOWNWARD DISPLACEMENT OF WATER. GASES THAT ARE INSOLUABLE or ONLY SLIGHTLY SOLUABLE IN WATER CAN BE COLLECTED BY THIS METHOD.
IDENTYFICATION OF OXYGEN
OBSERVE THE COLOUR AND ODOUR OF THE SAMPLE YOU COLLECTED. TURN THE GAS JAR UPWARDS AND INTRODUCE A GLOWING SPLINTER IN TO THE JAR AND IT WOULD REKINDLE. (LIGHT A TAPER OR EKEL AND BELOW OFF THE FLAME SO THAT ONLY THE GLOW REMAINS)IN THIS CASE THE GAS DOES NOT BURN, BUT THE GLOWING SPLINT ALONE REKINDLESTHIS SHOWS THAT OXYGEN IS NOT A COMBUSTIBLE GAS BUT ONLY A SUPPORTER OF COMBUSTION.
Photosynthesis
Steel Production
Molten pig iron is poured into a basic oxygen furnace (BOF) for conversion to steel. Steel is a form of iron produced from iron ore, coke, and limestone in a blast furnace. Excess carbon and other impurities are removed to make a strong steel.
USES OF OXYGEN GAS
We may be knowing that oxygen gas in the atmosphere which is only 21% is needed by living things for respiration. Some instances in which oxygen is used are given below.
1.For the oxy-acetylene flame used in cutting and welding metals.
2.For diving.
3.For patients having breathing difficulties.
4.Matches burn because the material in their tips combines with an invisible gas, oxygen, in the air. Never play with matches—you might burn yourself or start a fire by accident.
Hard Disk
The most commonly used device to storedata in the computer is the hard disk. This is fixed as a closed unit inside the computer.
There are different capacities in hard disk according to your requirment.
In hard disk, data are stored in platters and there can be several platters ina hard disk. All these platters are fixed on one spildle. All these are rotated together in the same speed whilw a resd / write head fixed in each platters separateley to read and write.
The speed of the hard disk is measured using its access time. This access time taken a vert small value andits measured in milliseconds (thousand unit per second)
ZIP DISK and JAZZ DISK
ZIP DISK and JAZZ DISK are almost similar to floppy while the capacity them is several time larger than that of floppy. The capacity of the zip range from 100MB to 750MB. That mean, that the data of 500 floppy or morecan be stored in one zip. The capacity of jazz is 1 GB and 2 GB.
Floppy disk
The floppy disk which are read and written in a very low speed in floppy disk and their capacity is very small compared to other data storage units. Floppy disk were produce various sizes such as 8, 5.25 and 3.5 incheswhile only 3.5 inches floppydick are available today.
One advantage of floppy disk is that they are portable. However\, since their capacity is small, moving the large filesused today here and there is in convenient.
Secondary storage unit(Auxiliary Memory)
Secondary Storage Unitsare used to store data stedily and safely as required for a particular duration. Many secondary storage units areused to store data and given below are some of main units.
Primary cache memory/level 1 (L1) and Secondary cache memory/level 2 (L2)
Primary cache memory/level 1 (L1)
Primary cache memory is created in the relevant CPU itself and it possess a very small capacity. When data and information are needed for the CPU, the first things chocked to seewhether thosearethere is L 1.
Secondary cache memory/level 2 (L2)
L2 , which is fixed on the motherboard very closedto the CPU, posses more capacity compared to the primary cache memory. Futher, the speed of theL2 is less than the L1
Cache memory
The data needed for the CPU gae through RAM. However, RAM does not have the ability to suply data in required speed of the CPU. The reason for this isspeed o the RAM is less than the speed of the CPU. Cache Memory is used to get rid of this shorting.
There are two ways in Cache Memory;
1.Primary cache memory/level 1 (L1)
2. Secondary cache memory/level 2 (L2)
Read only memory
The data or information saved in the ROM,which is called ROM and which belongs to the type of non-volatile memory, will hnoe be lost in a power failure.
All the necessary information is saved on the ROM only by thecomputer producing companies and it is possible toupgrade / update this memory when necessary in modern computers.
Raccess memory
The mein task of the Random Access Memory, which isalso called RAM, is to store data temporarily whichare needed to the Central Processing Unit. Everything in the RAM, which belongs to the typeof Voltile memory, is lost with a power failure. Therefore, all the data or information which is considered to be important should be important should definitely be saved in a unit of secondary memory.
The capacity of the random accsess memory is vital for the performance of a computer. Further, it is possible to enlarge the capacity of the Random Access Memory adding memory units as required.
Volatile memory and Non - Volatile memory
Volatile memory
The special features of the volatile memory isthat the data or information saved in it can be lost as soon as a power failure occurs. Random Access Memory mentionedabove also belongs to this . That means all the data or information saved in the Random Access Memory will be lost in a power failure.
Non - Volatile memory
The data and information saved here isstable anda powerfailure does not cause any effect to this. Read Only Meomory which is mentioned above also belongs to this type.
The special features of the volatile memory isthat the data or information saved in it can be lost as soon as a power failure occurs. Random Access Memory mentionedabove also belongs to this . That means all the data or information saved in the Random Access Memory will be lost in a power failure.
Non - Volatile memory
The data and information saved here isstable anda powerfailure does not cause any effect to this. Read Only Meomory which is mentioned above also belongs to this type.
Storage data or sorting
Primary storage unit are produced using semiconductors while Magnetic technology or Optical technology is used to produced Secondary Storage Units.
the maiin task of the primary storage is to store data temporarily to provide the necessary data to the Central Processing Unit. The main task of the secondary Memory is to store data, instructions and information needed for the future.
The main primary storage is to store data temporarily to provide the necessary data to th central processing unit. The main task of the secondary memory is to store data, instructions and information needed fo the future
Sound Port
Sound ports are used to connect Speakers, Microphones and External sound generating devices as required for the computer. These sound ports cannot be seen in some computers and in such situations, multimedia kits / circuits should be bought separately to connect sound devices.
USP (Universal Serial Bus Port)
The most popular port use in modern computers is the USB Port. Most of the devices used with the computer today are connected to the computer using USB Ports. Most of the input and output devices such as Keyboard, Mouse, Printer, Digital cameras or MODEMs can be connected to the computer very easily using USB Ports.1.Most of theUSB devices can be operates as soon as those are connected to the computer using USB ports. There is no need to install running / driving programmes here. This process is called Plug and Play.
2.The electricity needed for most of the USB devices is gained through the connected of USB port itself. That is another special feature.
3.Another important facility is the ability to connect and disconnect USB devices without shuting down the computer. This process is called Hot Pluggable or Hot Swappable.
4.The ability to connect various 127 devices through one USB Port is another special feature.
5.USB 2.0 ports possess the ability to communicate data in the speed of 480 megabytes per second. (480 Mbps)
Moniter Port
Moniter port is used to connect the computer screen which is the main device to give the output of the computer processed informations. This contains fifteen pins which are arranged in three lines
Network Port
Several computers should can be connected to build a computer Network ports are used to connect network cables to build such a computer network.
Modem Port
MODEM device is used to connect the computer to Internet and also to send faxes using the computer. The MODEMS fixed in the computer are called Internal MODEMS while the MODEMS fixed outside the computer are called External MODEMS.faxes are not sent through the computer.
Mostly two ports can beobserved in MODM device to fix telephone wire. The place which connects the telephone wire to the computer is mentioned as ‘Line in’ while the telephone connection which is fixed externally is mentioned as ‘Phone’. It is possible to take telephone call in in normal way through this instanceswhen the computer is not connected to the internet.
Parallel Port
Parallel ports is used to connect parallel devices to the computer such as printer and scanner. This normally called the printer port as well and this contains twenty five pins. Serial Ports
These ports are used to fix serial devices to the computer. These ports are specially used to fix Modems which are connected externally. Further, these ports are used to fix serial Mouse as well. There are two types of serial ports and one type contains nine pins while the other type contains twenty five pins. PS/2 ports
These ports are used to fix PS/2 Key boards and PS/2 Mouse. These two ports are always situated close to each other and it should be made sure that you fix the keyboard and the Mouse to the correct port. You can use the colours of the ports for this. The port for the keyboards is in green Further in most of the keyboards, there are sybols to idetify these ports. Computer Motherboard
Almost all the ports which are required to fix external devices to the computer are there in the Motherboard. It is impossible to view this computer Motherboard externally while the Ports can be seen iat back or sometimes in front of the computer. If you observe the computer, you will be able to see all these Ports very clearly.
Storage Devices.
Storage Devices, which are used to store data and information, are also called Backing Storageand Extra Memory. Hara Disks, Compact Disks and Digital Versatilt Disks are commonly used for this.
Speed of Computer
when considering the central processing Unit. Its speed is an important factor. The computer speed is sometimes called the clock speed as well. The unit Herts (Hz) is use to measure the speed of the Central Processing Unit while units such as megahertz (MHz) and gigahertz (GHz) are used to measure the speed of modern computer. When comparing computers, its speed is considered one strong factor.
1000 Hz = 1 kHz
1000 kHz = 1 MHz
1000 MHz = 1 GHz
The maximaum Bits used for calculations or strong at a time is considered to measure the capacity of the Central Processing Unit. This is also called the word size of the computer as well.
Intel and AMD (Advanced Micro Devices) can be mentioned as examples for the pioneering companies which produced Central Processing Units.
READ ONLY MEMORY – (ROM)
The data which are in read only memory cannot be easily changed or deleted as this memory is permanent. The necessary data permanently stored there by the company which produced the computer. This is also called the memory which can only be read. A few ways of read only memory can be noticed.01.Programmable Read Only Memory – (PROM).
02.Erasable Programmable Read Only Memory – (EPROM).
03.Electrically Erasable Programmable Read Only Memory – (EEPROM).
Random Access Memory – (RAM)
The data stored in the Random Access Memory (RAM) will be lost when the computer is shut down or in an electric failure as this memory is temporary. Same as the data can be collected as required in the random access memory (ram), those data can be changed and deleted. There are two main ways in the random access memory (RAM).
1.Static Random Access Memory (SRAM).2.Dynamic Random Access Memory (SRAM).
CENTRAL PROCESSING UNIT.
Central processing unit also called the heart of the computer. This consist of three parts;
1.Control Unit (Cu).3. Memory.
1 . Central Unit (CU).
All the controlling of the computer is done by this unit. This controls all the parts of the computer is giving the required command when necessary.
2 . Arithmetic and Logic Unit (ALU).
This unit does all kinds of calculations and reasoning.
3 . Memory.
The memory is used temporarily to store the data which are ready to be sent to the central processing unit for calculations or processing and the information which are ready to be sent out from the central processing unit. two kinds of memory can be seen in computer.
1. Random Access Memory – (RAM)
2. Read Only Memory – (ROM)
OUTPUT DEVICES.
The devices used to get the computer processed data and information out are considered here. Many devices can be used here and give below. 
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