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# titrations watch

1. titration 2 details:
final burette reading : 28.00 cm^3
so volume of NaOH used : 27.95 cm^3
q) the burette used in the titration had an uncertainty for each reading of +-0.05 cm^3... identify by letter which one of the following should be regarded as the true value of the titre in the titration number 2

X: between 27.90 cm^3 and 28.00 cm^3
Y: between 27,925 cm^3 and 27.725^3
Z: between 27.85 cm^3 and 28.05 cm^3

i dont understand whether we should add and subtract 0.05 from the final reading or the volume of NaOH used bcz the markscheme answer is Z,, it doesnt make sense cos it seems like once it subtracted from the final result and the other it added 0.05 to the volume of NaOH used ... plus im confused whether we should add and subtract 0.10 since its titration so burrette is used twice?????????? can someone pls explain this.. thanks x
2. Imagine the worst case:

The initial reading (of 0.05) was over by the 0.05 uncertainty. i.e the true reading was 0.00. Imagine the final reading was under by 0.05, i.e. the true reading was 28.05. i.e. the true titre was 28.05

Now reverse all the numbers and you get 0.10 and 27.95 i.e. 27.85.

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