The following measurements were made to determine the density of a material whose value was, according to the handbook of chemistry and physics, 1.24 g/ml trial #1 1.24 g/ml trial #2 1.22 g/ml trial #3 1.22 g/ml what general statement can be made on the accuracy and the precision of these results. click on all that apply (2 points) 1.these results are accurate because the collected data is very close to the actual value 2.these results are accurate because all three trials are within a very close range. 3.these results are precise because the collected data is very close to the actual value 4.these results are precise because all three trials are within a very close range. 5.these results are neither accurate nor precise.

1.These results are accurate because the collected data is very close to the actual value.

4.These results are precise because all three trials are within a very close range.

Explanation:

Although in the ordinary language the terms precision and accuracy may be confused, in science those terms refer different properties of the measurements.

The accuracy  is how close a measurement is to the true value, while the the precision refers to the reproducibility and repeatability, this is how the results show  the same (close) value.

To differentiate precision and accuracy, It is very illustrative, to use the image of a throwing arrows to a target: if the arrows get close to the center of the target, then the results are accurate (close to the goal). If the arrows are not close to the cener of the target, but they are all close to each other, then the result is precise (the arrows land, approximately, in the same spot every time).

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g