In most experiments, what is the least number of measurements (trials) when you
ID: 475543 • Letter: I
Question
In most experiments, what is the least number of measurements (trials) when you are making quantitative measurements in lab? the choices are: (1), (2), (3) __________________________ If a student determined that the volume of a sample of water is 11.4 mL, and its mass is 10.98 g, what should the student record as the experimental density of the water sample, with the correct number of significant figures? the choices are: (1.038 g/mL), (1.04 g/mL), (0.963 g/mL), (0.96 g/mL), (125 g/mL) __________________________ A student determines the mass of a sample of water by determining the mass of an empty container (99.20 g) and the mass of the container including the sample of water (108.23 g). Use significant rules (for subtracting) to determine the mass of the water sample alone, to the correct number of significant figures. the choices are: (9 g), (9.0 g), (9.03 g), (9.030 g), (9.0300 g) __________________________ After determining the density of three samples of water, each at 22.0(C, Anna calculated an average density for the three trials to be 1.048 g/mL. Use Appendix J in your lab manual to find the accepted density value of water at this temperature, and calculate the percent error for her average density result. the choices are: (3.197%), (1.050%), (5.034%), (9.521%), (0.9521%) In most experiments, what is the least number of measurements (trials) when you are making quantitative measurements in lab? the choices are: (1), (2), (3) __________________________ If a student determined that the volume of a sample of water is 11.4 mL, and its mass is 10.98 g, what should the student record as the experimental density of the water sample, with the correct number of significant figures? the choices are: (1.038 g/mL), (1.04 g/mL), (0.963 g/mL), (0.96 g/mL), (125 g/mL) __________________________ A student determines the mass of a sample of water by determining the mass of an empty container (99.20 g) and the mass of the container including the sample of water (108.23 g). Use significant rules (for subtracting) to determine the mass of the water sample alone, to the correct number of significant figures. the choices are: (9 g), (9.0 g), (9.03 g), (9.030 g), (9.0300 g) __________________________ After determining the density of three samples of water, each at 22.0(C, Anna calculated an average density for the three trials to be 1.048 g/mL. Use Appendix J in your lab manual to find the accepted density value of water at this temperature, and calculate the percent error for her average density result. the choices are: (3.197%), (1.050%), (5.034%), (9.521%), (0.9521%)Explanation / Answer
Q1. In most experiments, what is the least number of measurements (trials) when you are making quantitative measurements in lab?
the choices are: (1), (2), (3)
Ans. (3)
In most experiments, at least three (3) quantitative measurements are recorded as a standard protocol. It helps in statistically accounting the possible pipetting/ weighing/ handling or other errors made during the experiment.
__________________________
Q2. If a student determined that the volume of a sample of water is 11.4 mL, and its mass is 10.98 g, what should the student record as the experimental density of the water sample, with the correct number of significant figures?
the choices are: (1.038 g/mL), (1.04 g/mL), (0.963 g/mL), (0.96 g/mL), (125 g/mL)
Ans.
Given, I. volume of water = 11.4 mL ; number of significant figures = 3
II. Mass of water = 10.98 g ; number of significant figures = 4
Density of water = mass / volume
= 10.98 g/ 11.4 mL
= 0.96315789473684210526315789473684 g/mL
Rule: In multiplication and division of significant figures “ the answer can’t have more significant figures than the least precise number among those being multiplied or divided, respectively”. So, the answer can’t have more than 3 significant figures (Note: 11.4 mL is the least precise number among 11.4 and 10.98).
Thus, Density of water = 0.963 g/mL ; [number of significant figures = 3 ]
__________________________
A student determines the mass of a sample of water by determining the mass of an empty container (99.20 g) and the mass of the container including the sample of water (108.23 g). Use significant rules (for subtracting) to determine the mass of the water sample alone, to the correct number of significant figures.
the choices are: (9 g), (9.0 g), (9.03 g), (9.030 g), (9.0300 g)
Ans. Mass of water = (Mass of container + cylinder) – (mass of empty cylinder)
= 108.23 g – 99.20 g
= 9.03 g
Rule: The number of digits after decimal in the answer is equal to the least precise number among those being subtracted. Here, both the values being subtracted have two digits after decimal, so the resultant answer shall also have two digits after decimal.
__________________________
After determining the density of three samples of water, each at 22.0(C, Anna calculated an average density for the three trials to be 1.048 g/mL. Use Appendix J in your lab manual to find the accepted density value of water at this temperature, and calculate the percent error for her average density result.
the choices are: (3.197%), (1.050%), (5.034%), (9.521%), (0.9521%)
Ans. Density of water at 220C = 0.9977735 g/mL
Average density obtained = 1.048 g/ mL
Error in density = Obtained value – standard value
= 1.048 g/ mL - 0.9977735 g/mL = 0.0502265 g/mL
= 0.050 g/mL ; [number of digits after decimal in ans = 3. see “rule” in answer 3]
% error = (error / standard value) x 100
= (0.050 g ml-1 / 0.9977735 g ml-1) x 100
= (0.050)Note1 x 100 ; [Note 1: see rule in answer 2]
= 5 % ; [Note 1: see rule in answer 2, for not writing 5.000]
“Each step in calculation account significant figures”.
You have nearest value of 5.034 compared to 5.
So, among the given options, the correct answer = 5.034 %
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