Densities of Liquids and Solids Questions 1. To how many significant figures can
ID: 704813 • Letter: D
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Densities of Liquids and Solids Questions 1. To how many significant figures can the density of the metal be properly reported? Explain why the value obtained for the density of the metal is likely to have a larger percent error than the value obtained for the liquid. 2. 3. Ifyour piper was calibrated incorrectly sothat it transferred 5% too little solution, the cal- -(larger than/smaller than/the same as) culated density of the liquid would be, the correct value. Explain your answer. 4. The data for Part A illustrates which general law? You determined the density of water by two methods (using pipets vs. burets). Using the standard deviation as your guide, which method resulted in better precision?( Appendix E) Which method resulted in better accuracy (lower percent error)? 5.Explanation / Answer
1) The weight is taken in 5 significant figures.the volume is measured in 4 significant figures. we can opt for which ever is less. So the density is calculated is obtained in 4 significant figures. We can report the density in 4 significant figures. Since all the digits are non Zeros we can report the answer as 7.333 g/cm3.
3)The mass of water was 24.815 g.
Volume would be 25 ml
So density = 24.815 / 25
= 0.9926 g/ cm3
As per the question the pipette delivered 5 % less solution. The pipetted solution was 25 ml.
5 percentage of 25 ml = 5 * 25 / 100
= 1.25 ml
If this wrongly calibrated pipette was used in the measurement ,it would have delivered 1.25 ml less. thhat means 23.75 ml.
( I suppose density of water is taken as 1 g / cm3 in the calculation)
The mass of water was 24.815 g.
Volume would be 23.75 ml
So density = 24.815 / 23.75
= 1.045 g / cm3
From the calculation it is clear that the density value has increased compared to the corrected value. The concept is density = mass/ volume. that means volume lies in the denominator. If the value of volume decreases , the vaule of density increases.
4) The general law regarding this is the weight of a whole object is equal to the sum of the weights of its parts. It is to show that the coins weighed individually or together weights the same.
(when the coins are weighed individually the weight observed was , 2.498 and 2.499 . When weighed together according to mathematical calulation it should have shown the value 4.997. But instead it has shown the value 5.002. This means that the balance itself has an accuracy. The percentage error shown by the balance was 0.1 %. This means the slight variation occured is assigned to the precission of the balance.)
5)From the calculation itself it is shown that the standard deciation for pipetted volume density is lesser than the density calulated using buretted out volume. The pipetted volume density had standard deviation 0.00109 and the density of buretted volume was 0.0204 .that means the Accuracy is more observed in pietted out volume. Precission means how close repeated measurements are to each other. That means precission is better when volume was delivered using pipette.
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