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# Uncertainty in burette reading! watch

1. In a practical paper the question of titration had a part asking 'maximum uncertainty in a single reading with a burette'. According to physics, the answer to this should be 0.10 cm3(Because we take uncertainty as least count of the measuring instrument), but the mark scheme gives 0.05 cm3 as the answer. Why is that so? - does the uncertainty concept different in chemistry than physics?
2. (Original post by Zishi)
In a practical paper the question of titration had a part asking 'maximum uncertainty in a single reading with a burette'. According to physics, the answer to this should be 0.10 cm3(Because we take uncertainty as least count of the measuring instrument), but the mark scheme gives 0.05 cm3 as the answer. Why is that so? - does the uncertainty concept different in chemistry than physics?
he resoloution of a burette for a single reading is +-0.05 cm^3 however when you take more then one reading you have to multiply it as you have obv taken more then one reading so in a titration you take 2 readings so the uncertianity would be 0.05x2 =+-0.1 cm^3
3. (Original post by hazbaz)
he resoloution of a burette for a single reading is +-0.05 cm^3 however when you take more then one reading you have to multiply it as you have obv taken more then one reading so in a titration you take 2 readings so the uncertianity would be 0.05x2 =+-0.1 cm^3
BUT we take least count of the instrument as the uncertainty. The least count of a burette is always 0.10cm3, isn't it? And I know that the error is multiplied by two whenever we subtract or add two same readings.
4. (Original post by Zishi)
BUT we take least count of the instrument as the uncertainty. The least count of a burette is always 0.10cm3, isn't it? And I know that the error is multiplied by two whenever we subtract or add two same readings.
In chemistry we don't use the least count.

Each instrument has a considered error and the burette can be 'read' to within half of 0.1ml = 0.05. Hence we take the error to be +/- 0.05
5. (Original post by charco)
In chemistry we don't use the least count.

Each instrument has a considered error and the burette can be 'read' to within half of 0.1ml = 0.05. Hence we take the error to be +/- 0.05
So in chemistry do we take the uncertainty as half of the least count?
6. (Original post by Zishi)
So in chemistry do we take the uncertainty as half of the least count?
Like I said, it depends on the instrument, and even then there is little consensus.

A 2 dp electronic balance is sometimes taken as +/- 0.01 and sometimes as +/- 0.005.

The main thing is to understand the concept and to evaluate the importance of each inaccuracy on the final value.
7. (Original post by charco)
Like I said, it depends on the instrument, and even then there is little consensus.

A 2 dp electronic balance is sometimes taken as +/- 0.01 and sometimes as +/- 0.005.

The main thing is to understand the concept and to evaluate the importance of each inaccuracy on the final value.
As about electronic balance the least count is +/- 0.01, so that's why we take it as least count, don't we? Sorry, I'm a little confused. Could you please post something on your own Or a link which could give me this concept?

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