# Chemistry help

posted by
**Bryant**
.

Hey...I just want to make sure my answers to these questions are correct...

1. d=2.507 g/1.22 mL = 2.054918033 g mL^-1

explain how both the rules for significant figures and the random error calculation (p(d) = +-0.34 g mL^-1) indicate that the digits after the hundreths place have no meaning in this measurement.

Answer: The rules for significant figures and the random error calculation indicate the digits after the hundredths place have no meaning in this measurement because if the experiment was performed again, the same exact number would not be calculated again because of possible fluctuations and irreproducibility of an instrument.

2. although the beads used for experimental mass and volume determinations are to be chosen randomly, certain care should be taken not to choose beads that would introduce systematic errors. how would the accuracy of the volume determination be affected (answer \\\"high\\\", \\\"low\\\", or \\\"no significant change\\\") by using beads that are...

warped (nonspherical)

A: no sig change

hollow

A: high

slightly chipped

A: low

slightly chipped with a large air bubble that has become attached to the outside of the bead

A: high

3. assume that the estimates of the standard deviation for the mean mass of a series of three measurements, a serious of six measurements, and a series of nine measurements were identical. why will the confidence intervals for three mean masses differ? which different is greater: that between the CI for three measurements and the CI for six measurements; or that between the CI for six measurements and the CI for nine measurements? Briefly explain.

A: The confidence intervals for the three mean masses will differ because as the number of beads increases, the confidence interval will decrease. There is a greater possibility of getting a better confidence interval.

The difference between the CI and three measurements is the greatest because there is little degree of freedom for the selection.