HEY MATES
1. Why is Plaster of Paris stored in a moisture proof container?
2. What do you mean by neutralization reaction? Give two examples.
3. Mention two uses of baking soda and washing soda.
4. Why does a milkman add a small amount of baking soda to fresh milk to shift the pH of fresh milk from 6 to slightly alkaline?
5. Why do acids not show acidic behavior in the absence of water?
6. Rain water conducts electricity but distilled water does not. Why?
7. Why don’t we keep sour substances in brass and copper vessels?
8. What is the common name of CaOCl2?
9. Name the compound used for softening hard water.
10. What happens when baking soda is heated?
11. Give the properties and uses of bleaching powder.
12. Give a few uses of acids, bases and salts respectively.
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Answers
1Plaster of Paris is Caso4.1/2H2O ...which when exposed to air for gypsum which is a hard mass..
2the reaction between n acid and a base to form salt and water is called nuteralization reaction....Eg_HCl+NaOH-->NaCl+H2O
3 baking soda is used as an antacid and is also used for making bakery products soft and fluffy........washing soda is used in laundry and is also used to remove permanent hardness of water
4in this way the milk is made slightly alkaline and ph is decreased due to which it does not gets spoilt easily
5because to show their acidic behaviour they must produce hydrogen ions which are produced only in presence of water
6rain water contains acids and some salts as it passes through various layers of atmosphere which contains acidic gases ....so it form ions dur to which it conducts electricity whereas distilled water does not contains any ions
7sour substances contains acids which make toxic substances on reacting with copper or brass vessels when kept in them
8bleaching powder
9washing soda
10NaHCO3-->Na2CO3 +H2O+C02
11 properties are that it is a light yellow colored solid and it is formed by passing chlorine gas over dry soaked lime
Uses are it is used in paper industry and it is used to kill germs in pools and water bodies
12 acids are used to clean surfaces of metals
Bases are used to get relief from acidity(weak bases) and stronger ones are used to make fertilizers
Salts have various purposes as mentioned in the chapter ........
Here are our answers took me a lot of time
ANSWERS
1.IF PLASTER OF PARIS GETS WET IT TURNS INTO GYPSUM.SO IT IS STORED IN A MOISTURE PROOF CONTAINER.
2.NEUTRALIZATION REACTION IS THE REACTION BETWEEN A STRONG ACID AND A STRONG BASE.THE PRODUCT OF THE REACTION ARE WATER AND SALT.
HCl+NaOH------------>NaCl+H₂O
HBr+KOH-------------->KBr+H₂
3.->IT IS USED IN GLASS ,SOAP AND PAPER INDUSTRIES.
->IT IS USED FOR REMOVING PERMANENT HARDNESS OF WATER.
4.HE ADDS THEM TO CHANGE THE pH VALUE OF FRESH MILK FROM 6 TO ALKALINE SO THAT IN THE BASIC FORM IT WON'T GET SPOILED EASILY.
5.THE DISSOCIATION OF HYDROGEN IONS FROM ACID OCCURS ONLY IN THE PRESENCE OF WATER.
6.RAIN WATER CONTAINS IONS SO IT CONDUCTS ELECTRICITY WHEREAS IN DISTILLED WATER THERE IS NO IONS.
7.SOUR SUBSTANCES REACTS WITH COPPER AND BRASS AND A TOXIC COMPOUND IS FORMED WHICH IS TOTALLY UNFIT FOR CONSUMPTION.
8.THE COMMON NAME FOR CaOCl₂ IS BLEACHING POWDER.
9.WASHING SODA IS USED FOR SOFTENING THE HARD WATER.
10.WHEN BAKING SODA IS HEATED,IT LOSES CARBON .
11.PROPERTIES:
COLOUR:PALE YELLOW
SMELL:CHLORINE
SOLUBILITY:SOLUBLE IN WATER
USES:
->FOR BLEACHING COTTON AND LINEN.
->USED AS AN OXIDISING AGENT.
12.ACIDS:
-> TO REMOVE RUST
-> FOR MINERAL PROCESSING
BASES:
->used in manufacture of soap, paper and the synthetic fiber rayon.
-> used in the manufacture of bleaching powder.
SALTS:
-> production of pottery, soap, and chlorine
-> in the kitchen as free-flowing table salt, rock salt, sea salt, or kosher salt.