Biology; Chemistry; Physics: Post your doubts here!

[Birdie Honey]

Explain me the need of these fixed points too!please
YEAH! thankyou for your response.

 

[Birdie Honey]

and would you please tell me why do we need(not how) to do this?
really grateful for your previous reply!thankyou

 

[daredevil]

thermometers!!!

see u know that u need to have a scale of at least 0 - 100 *C and all the other temperatures will come within those points.... and u also know that mercury exapands in direct proportion (or it has a linear expansion) with temperature which means it will expand the same length for every increasing *C or *F ... so all u need now is two fxed points in b/w which u can easily divide ur scale and take a reading. for determining those two fixed points u take the two most obvious temperatures i.e. pure ice's melting point and pure water's boiling point to determine 0*C and 100*C respectively.
btw... PURE water is not necessary in determining 100*C but is preferable. it is not necessary bcuz the thermometer is kept above the water surface i.e. in the steam and measures the steam's temperature so slight impurities in the water are not going to affect your readings.

 

[multixamza01]

PURE water is not necessary in determining 100*C but is preferable. it is not necessary bcuz the thermometer is kept above the water surface i.e. in the steam and measures the steam's temperature so slight impurities in the water are not going to affect your readings.

Actually , pure water does matter. Impurities not only cause the boiling point to rise but also affect it's sharpness. Meaning that water with impurities would boil over let's say a range of 102*C- 104*C. So your fixed point is wrong.
So yeah , you gotta stick with Pure Water. ''Made In China'' water affects readings

 

[daredevil]

Actually , pure water does matter. Impurities not only cause the boiling point to rise but also affect it's sharpness. Meaning that water with impurities would boil over let's say a range of 102*C- 104*C. So your fixed point is wrong.
So yeah , you gotta stick with Pure Water. ''Made In China'' water affects readings

thnx for the warning but i just prepared this topic today and i said that IN MOST CASES (i may have written mostly but watever) it impurities do not affect the temperature of the steam just above the water. i didn't tell him to used swamp water i just said that minor impurities will not afect it ...
and yes "Made in China" kind of water is out of my comprehension ... lol

 

[daredevil]

and would you please tell me why do we need(not how) to do this?
really grateful for your previous reply!thankyou

actually wen u read the answer to how u automatically get the answer to why 2 .... for making measuring instrument we nee to have a standard or a scale for it (eg. a vernier caliper, metre rule, ammeter, etc.) same is the case w/ a thermometer .... bcuz we need it to measure temperatures of other things so we need to determine the scale to identify our readings and that is why we need to get the fixed points too... flower it up in ur own words for an answer... I hope that helped.

 

[Vogue]

and would you please tell me why do we need(not how) to do this?
really grateful for your previous reply!thankyou

your question as to " why do v need these two points" then the answer is the same that we need it to calibrate a thermometer and mark all the divisions to get the temperature readings.....

 

[Ashraful Ahsan]

K

Re: Biology,Chemistry & Physics Help Available Here !

Need help. What is the chemical formula of potassium sulfate? is it K2SO4 or KSO2?

K2SO4. The valencies of the radicals (SO4,NO3,OH,etc) are always fixed.

 

[multixamza01]

K
K2SO4. The valencies of the radicals (SO4,NO3,OH,etc) are always fixed.

Really? Wow ... you saved me mate. Really thanks , i was doomed until you told me that .

 

[Birdie Honey]

sure it did!!thanks

 

[Birdie Honey]

thanks!!i got it!

 

[Birdie Honey]

hey!!you should have told us before we would have saved you long ago.we dont want any of cie students to die!!!!

 

[snowbrood]

just explain in terms of the density,like in humid air the mass of water vapour to air is more vapours per the unit volume and thereofre the more denser it is !

no its is why dont u get it.. its too simple wet air has more water molecules per unit volume doesnt it ?? water molecule weights 18 doesnt it.. see take it as this u have 1 cm3 of wet air that have 98% water molecules so lets consider the mass of 1cm3 of wet air to be that of the water i.e 18... while i have 1 cm3 of dry air it has 98% nitrogen and oxygen molecules there mass combined is 28+32 so which is denser its so simple now

 

[snowbrood]

well can u pls make me comprehend more clearly...i am unable to understand...

no its is why dont u get it.. its too simple wet air has more water molecules per unit volume doesnt it ?? water molecule weights 18 doesnt it.. see take it as this u have 1 cm3 of wet air that have 98% water molecules so lets consider the mass of 1cm3 of wet air to be that of the water i.e 18... while i have 1 cm3 of dry air it has 98% nitrogen and oxygen molecules there mass combined is 28+32 so which is denser its so simple now​

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[Khalil Rizvi]

Difference between Evaporation and Boiling?

 

[khanrocks20]

i need organic chem notes please.. my mocks tomorrow.. olevel chem

 

[khanrocks20]

Difference between Evaporation and Boiling?

Evaporation occurs at any temp whereas boiling occurs at 100 degree celcius. evaporation takes place at surface wheras boiling takes place throughout the liquid.

 

[Birdie Honey]

1.BOILING OCCURS AT WIDE TEMPRATURE RANGE WHILE BOILING OCCURS AT A FIXED TEMPRATURE.
2.IN BOILING BUBBLING OCCURS WHILE ITS NOT THE CASE WITH EVAPORATION.
3.EVAPORATION DOESNOT NEED ANY HEAT SUPPLY WHILE BOILING DOES.
4.BOILING OCCURS WITHIN THE LIQUID AND EVAPORATION ON THE SURFACE OF LIQUID.
5.BOILING IS A FAST PROCESS EVAPORATION IS MUCH MORE SLOWER.
6.BOILING OCCUS AT A FIXED TEMPRATUR,AND EVAPORATION CAN OCCUR AT ANY TTEMPRATURE.
SO,SEE!!!ITS PRETTY EASY!!!!

 

[mintchocolate4567]

1)explain why hormonal responses are slower than reflex actions?
2)explain 'stereoscopic vision.
3)explain the nitrogen cycle.
P.S nobody answered my questions relating the atp paper! :/

 

[mintchocolate4567]

how to check for a zero error in a)voltmeter b)ammeter????
P.S is that even included in our syllabus?? -_-

and als0 if anyone can answer the following questions:

Q9: WHY THE TEMPERATURE 20OC IS MARKED ON THE MEASURING CYLINDER?

Q30: BEFORE CLOSSING THE SWITHCH, WHY IS THE RHOSTATE ADJUSTED TO ITS MAXIMUM VALUE?

Q32: WHAT IS THE ADVANTAGE OF USING SMALLER COMPASS?

Q59: WHAT IS MEANT BY
A)RESPONSIVENESS
B)LINEARITY
C)SENSITIVITY OF A THERMOMETER?

Q69: WHY THE CROSS-SECTION OF THE STEM OF THERMOMETER IS PEAR-SHAPED?

Q19: WHY THE FULCRUM SHOULD HAVE SHARP EDGE?

these^^^^