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# Chemistry titrations Watch

1. Hey guys got a titration question I need help with.

2Li(S) + 2H20(l) ---> 2LiOH(aq) + H2(g) Equation 1
LiOH + HCl --> LiCl + H20 Equation 2

Mass of Li used = 0.15
All recordings were to the nearest 0.05cm3.
Burette was filled with 0.100mol dm-3 HCl

I got the following readings,

28.85 and 26.15 to give a mean titre of of 27.5

I calculated the moles of HCl to be 0.00275

The question I'm stuck with is "Identify the most significant measurement error in this experiment. Explain your reasoning". Any help please?

I have been told to calculate the percentage error, but I'm unsure how to do it.

Many thanks.
2. (Original post by farhan123)
Hey guys got a titration question I need help with.

2Li(S) + 2H20(l) ---> 2LiOH(aq) + H2(g) Equation 1
LiOH + HCl --> LiCl + H20 Equation 2

Mass of Li used = 0.15
All recordings were to the nearest 0.05cm3.
Burette was filled with 0.100mol dm-3 HCl

I got the following readings,

28.85 and 26.15 to give a mean titre of of 27.5

I calculated the moles of HCl to be 0.00275

The question I'm stuck with is "Identify the most significant measurement error in this experiment. Explain your reasoning". Any help please?

I have been told to calculate the percentage error, but I'm unsure how to do it.

Many thanks.
Percentage error of any one step is the actual uncertainty of a reading divided by the actual recorded measurement and multiplied by 100.

The overall percentage error for a several step procedure is obtained by adding together the individual % errors.

The most significant is the biggest one.
3. (Original post by charco)
Percentage error of any one step is the actual uncertainty of a reading divided by the actual recorded measurement and multiplied by 100.

The overall percentage error for a several step procedure is obtained by adding together the individual % errors.

The most significant is the biggest one.
Thanks. Percentage error makes sense now. Do you know whether it is correct to calculate the percentage error for this question?
4. (Original post by farhan123)
Thanks. Percentage error makes sense now. Do you know whether it is correct to calculate the percentage error for this question?
If that's what you've been asked to do...
5. (Original post by farhan123)
Thanks. Percentage error makes sense now. Do you know whether it is correct to calculate the percentage error for this question?
comes under "explain your reasoning".... can't argue with correctly calculated figures!

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