A student wanted to measure 10cm3 of a solution as accurately as possible.
First, the student measured 10cm3 of solution into a beaker.
The solution in the beaker was then transferred to a measuring cylinder (making sure that there were no drops remaining in the beaker).
The student saw that there was less solution in the measuring cylinder than was transferred.
The measuring cylinder had 9.5cm3 of solution.
The student decided to measure 10cm3 of solution into a pipette, after noticing this discrepancy.
1) Taking into consideration percentage uncertainty why did there appear to be less solution in the measuring cylinder, than was transferred from the beaker. Fully explain this.
2) What is the total percentage uncertainty for this beaker and the measuring cylinder combined? Show your working out.
3) Was the student wise to measure the needed volume into the pipette, instead of either the beaker or the measuring cylinder? Fully explain your answer in detail. Give an explanation that shows your understanding of uncertainty too.
1) There appeared to be less solution in the measuring cylinder than was transferred from the beaker because of the uncertainty associated with the measurements. The beaker and the measuring cylinder both have a certain degree of uncertainty associated with them. The beaker has a greater degree of uncertainty than the measuring cylinder, meaning that the volume of solution measured in the beaker is likely to be slightly higher than the volume of solution measured in the measuring cylinder. This is because the beaker has a greater degree of inaccuracy than the measuring cylinder, meaning that the volume of solution measured in the beaker is likely to be slightly higher than the volume of solution measured in the measuring cylinder.
2) The total percentage uncertainty for this beaker and the measuring cylinder combined is 0.5%. This is calculated by adding the percentage uncertainty of the beaker (0.3%) and the percentage uncertainty of the measuring cylinder (0.2%) together.
3) Yes, the student was wise to measure the needed volume into the pipette, instead of either the beaker or the measuring cylinder. This is because the pipette has a much lower degree of uncertainty than either the beaker or the measuring cylinder. The pipette has a percentage uncertainty of 0.1%, which is much lower than the percentage uncertainty of the beaker (0.3%) and the measuring cylinder (0.2%). This means that the volume of solution measured in the pipette is likely to be much more accurate than the volume of solution measured in either the beaker or the measuring cylinder.