Transcript For an experiment, 9.7 mL of HCl are needed. What is
Virginia Standards of Learning Assessments
SOL Scientific Investigation
For an experiment, 9.7 mL of HCl are needed. What is the best instrument to use for measuring this volume?
A B C D
Beaker Erlenmeyer flask Graduated cylinder Test tube
Which of the following pieces of glassware can be used to measure the volume of a liquid with the greatest accuracy?
A B C D
Test tube Beaker Flask Graduated cylinder
To remove the sand first and then the salt from a mixture of sand and salt water, one combination of techniques you could use would be to first — A B C
evaporate and then distill evaporate and then condense filter and then evaporate
D
filter and then condense
A student used the ruler below to measure the length of a nail. The length of this nail, according to the precision of the ruler, is — A B C D
3.5 cm 3.55 cm 3.7 cm 3.75 cm
Most gases have the property of becoming increasingly soluble in a liquid as the temperature of the liquid decreases. Which graph shows this relationship?
Sig Figs
• • • • •
How is 0.00124 expressed in proper scientific notation?
A
1.24 x 10 -3
B C D
0.124 x 10 -2 1.24
1.24 x 10 3
The element chlorine exists as two naturally occurring isotopes. Cl-35 occurs 75% of the time and Cl-37 occurs 25% of the time. Which of the following calculations should be used to calculate the correct average atomic mass of chlorine?
A student measures the mass of a piece of copper three times and records the results in the following table: The actual mass of the copper is 28.7 grams. Which of the following is demonstrated in the student’s data?
A B C D
Accuracy Continuity Precision Reliability
The mass of an object was recorded as 9.93 g, 9.90 g, and 10.02 g, using an electronic analytical balance. What is the average of these three masses expressed to the correct number of significant figures?
9.93 + 9.90 + 10.02 / 3 = A B C D
9.9 g 9.95 g 10.0 g 10.00 g
A student conducted an experiment and was interested in the mass of the product of the chemical reaction. Some results of the experiment are shown above. What is the mass of the NaCl?
A B C D
0.75 g 1.75 g 2.25 g 2.50 g
44.45 g - 42.70 g
Measurement 1: 5.2 g Measurement 2: 5.4 g Measurement 3: 3 g Measurement 4: 2.45 g These data show repeated measurements of the same object which has a known mass of 5.38 grams. Which measurement is most accurate?
A
1
B C
2 3
D
4
A student wanted to calculate the formula for hydrated copper sulfate. After careful massing, she heated the compound to remove the water. She calculated the formula to be CuSO
4
4H
2
O. The actual formula was CuSO
4
5H
2
O. What is the most likely source of analytical error in the student’s experiment?
A B C D The water was not completely evaporated from the compound. The actual mass of the anhydrous CuSO 4 than the measurement.
was less The CuSO 4 reacted with elemental copper.
The atmospheric pressure prevented complete reaction.
If a student’s hand is accidentally exposed to an acidic solution, what should be done?
A B C D
Rinse the hand in a concentrated base.
Rinse the hand in running water. Wrap the hand in paper towels.
Cover the hand with oil.
What is the percentage of aluminum in aluminum oxide (Al 2 O 3 )?
A B C D
47% 48% 53% 54%
What is the percentage of aluminum in aluminum oxide (Al 2 O 3 )?
Molar Mass of Al 2 O 3 is 2(27.0) + 3(16.0) = 102 g Mass of just Al is 2(27.0) = 54.0 g
Al
% 54 .
0 102 .
0
x
100 53 %
What is the percentage of aluminum in aluminum oxide (Al 2 O 3 )?
A B C D
47% 48% 53% 54%
To determine the density of corn syrup, a student poured 3.0 mL of the liquid into a 10.0 mL graduated cylinder and massed the cylinder and contents. He determined the density to be 10.5 g/cm 3 . The accepted value for the density of corn syrup is 1.38 g/cm 3 . The most probable cause of error was that — A
the mass and the volume were multiplied
B
the mass of the cylinder was included in the density formula
C D
the graduated cylinder accuracy is only 0.5 mL the mass and volume were inverted in the density formula
A student was instructed to carry out an experiment that illustrates the law of conservation of mass. The teacher indicated that the experiment should be carried out three times. The student plans to report the average of the three results. What can the student do to maximize the reliability of the data collected?
A B C D Report the result that came closest to the class average.
Conduct each trial using the same balance. Report the average of the two most similar values only.
Perform each of the trials on different days.
A chemical engineer for a fertilizer company is determining the most efficient way to produce ammonia. The engineer carries out the Haber reaction under four different conditions. According to these data, which procedure gave the greatest percent yield?
A B C D
A B C D What is the Haber reaction?
N
2 (
g
) 3
H
2 (
g
) 2
NH
3 (
g
)
H
92
KJmol
1
You do not need this to solves the problem!
A chemical engineer for a fertilizer company is determining the most efficient way to produce ammonia. The engineer carries out the Haber reaction under four different conditions. According to these data, which procedure gave the greatest percent yield?
The one with the most!
A B C D
A B C D
According to the above data, which of the following represents the average density for sample X using the correct number of significant figures?
Hint: look at sigfigs in data. The least number is 2!
A B C D
1 g/mL 0.8 g/mL 0.81 g/mL 0.821 g/mL
At a constant volume, the pressure of a gas will increase as the temperature increases. Which of the following graphs shows that relationship?
A student must make a 3 M acid solution using a 5 M acid solution. Which of these is the safest way to make the solution?
A B C D
Slowly pour the 5 M acid into water Slowly add water to the 5 M acid solution Mix half the acid with water, then add the remaining water Mix half the water with the acid, then add the remaining acid
Which salt is most soluble in water at 90
º C
?
A B C D
NaClO 3 KNO 3 KBr NaCl
When examining the physical properties of an unknown substance, which of the following characteristics is unsafe to observe?
A B C D
Color Weight Form Taste
The density of an unknown metal was determined to be 2.85 g/mL. The actual density was 2.70 g/mL. What is the percent error in this determination?
A
0.056%
B C
0.15% 5.6%
%E
|
%E
D
known |
94.4%
2.70
experiment 2.70
|
x
100 al
|
x
100 5 .
6 %
A student uses a mortar and pestle to crush 1.0 g of marble chips and places them into a test tube. A whole 1.0 g marble chip is placed into a second test tube, and 5.0 mL of 6 M HCl is added to each test tube. The bubbling speed of the produced CO 2 gas is noted. This experiment is designed to study the effect of the — A B C D
introduction of a catalyst on reaction rate type of introduced acid on reaction rate surface area of a reactant on reaction rate temperature of a reactant on reaction rate
When CuSO
4
5H
2
O is heated in a crucible, there is a loss of water. How should a student determine the amount of water lost?
A B C D
Subtract the mass of the CuSO
4
from the mass of CuSO
4
5H
2
O Subtract the mass of the CuSO 4 5H 2 O from the mass of CuSO 4 Add the masses of CuSO and CuSO 4 4 5H 2 O Multiply the masses of CuSO H 2 O and CuSO 4
4
5
A student designed this experiment to study the effects of a catalyst on a reaction. Which trial serves as the experimental control?
A B C D
1 2 3 4
Which of these shows a volume of 1.25 liters expressed in milliliters?
A B C D
125 mL 12.5 x 10 1 mL 1.25 x 10 2 mL 1.25 x 10 3 mL
A student spills a diluted acid solution on his hand. He should — A B C D
wipe it off with a paper towel let it air dry apply a base solution to neutralize it rinse it off with running water
A student wanted to obtain a very accurate value for the volume of a piece of steel. He filled a 100.0 cm 3 cylinder to the 50.0 cm 3 graduated mark with water. After he carefully dropped the steel into the cylinder, the water level rose to the 55.6 cm 3 level. He reported the volume of the steel as 5.6 cm 3 . How could the student improve the reliability of his analysis?
A B C D
Report the volume as 56 mm
3
Fill the graduated cylinder to the 70.0 cm
3
mark before adding the steel Mass the steel and report its density in g/cm
3
Repeat the measurement many times and report an average value
If a student needed to obtain 8.0 mL of a liquid for an experiment, the appropriate piece of laboratory equipment to use would be a — A.
50 mL beaker
B.
1.0 mL pipet
C.
50 mL flask
D.
10.0 mL graduated cylinder
If a lab group were using hydrochloric acid to perform a substitution reaction, which precaution would not be a concern?
If a lab group were using hydrochloric acid to perform a substitution reaction, which precaution would not be a concern?
A.
Flammability
B.
Health
C.
Reactivity
D.
Contact
Which of the following best describes why an experiment should be repeated?
A.
To organize the data
B.
To produce a variety of results
C.
To include another variable
D.
To verify the observed results
The graph shows the rate of a certain reaction as a function of temperature. According to the graph, in order to double the rate of the reaction at 20° C, the temperature must be increased by approximately — A.
10° C
B.
20° C
C.
30° C
D.
40° C
A student obtained these data after measuring the mass of an object three different times. If the true value of the object’s mass is 5.550 g, these data are best described as —
• • •
First measurement: 6.293 g Second measurement: 6.294 g Third measurement: 6.295 g
A student obtained these data after measuring the mass of an object three different times. If the true value of the object’s mass is 5.550 g, these data are best described as — A. precise but not accurate B. accurate but not precise C. accurate and precise D. neither accurate nor precise
A team of chemistry students made the above measurements and density calculations of the same type of material. The accepted value (true value) of the density of the material is 5.72 g/cm3. Which trial has the least amount of absolute error?
The accepted value (true value) of the density of the material is 5.72 g/cm3. Which trial has the least amount of absolute error?
D
m
Which trial is closest to 5.72?
A.
1
B.
2
C.
3
D.
4
V
The figure shows an experimental setup used to separate the components of a colored ink sample. Which of the following describes this laboratory technique?
A.
Chromatography
B.
Filtration
C.
Decanting
D.
Distillation
Which basic lab technique involves the separation of a mixture’s components through differences in particle size?
A.
Filtration
B.
Extraction
C.
Distillation
D.
Crystallization
The graph shows the pressure of an ideal gas as a function of its volume. According to the graph, increasing the volume from 100 mL to 150 mL — A.
decreases the pressure by 80 kPa
B.
decreases the pressure by 160 kPa
C.
increases the pressure by 80 kPa
D.
increases the pressure by 160 kPa
How should 0.000365 be expressed in proper scientific notation?
A.
3.65 X 10
4
B.
365
C.
3.65
D
3.65 X 10
-4
SIG FIGS
•
The reaction times for three trials of an experiment are 90.3, 90.2, and 90.5 seconds. Which average time is expressed using the correct number of significant figures?
A.
90.3
B.
90.33
C.
90
D.
90.333
What is the name of the lab equipment shown ?
A.
Watch glass
B.
Crucible
C.
Beaker
D.
Evaporating dish
The melting point of a white solid substance was determined in four repeated trials to be 56.0
°
C, 55.0
°
57.5
°
C, 55.5
°
C, C. What temperature should be reported as the melting point as a result of these trials?
A.
55.0° C
B.
55.5° C
C.
56.0° C
D.
57.5° C
56.0 + 55.0 + 57.5 + 55.5 = 224/4 = 56.0
o C
Which is the best indicator for giving a color change at the equivalence point?
A.
Bromocresol green
B.
Indigo carmine
C.
Neutral red
D.
Phenolphthalein
Methyl mercury, found in some stream sediments, is highly toxic to animal life. Using the graphed results of the study shown, the best analysis of the data reveals that the methyl mercury concentration in the stream sediment is —
Using the graphed results of the study shown, the best analysis of the data reveals that the methyl mercury concentration in the stream sediment is — A
. steadily increasing, accelerating in the fall of each year
B.
increasing overall but reaches a minimum
C.
in the winter constantly declining throughout each month
D.
of the year decreasing but reaches a maximum at the end of summer
What is a possible cause of a large percentage of error in an experiment where MgO is produced from the combustion of magnesium? Hint: eliminate choices!
A.
Not all of the Mg has completely reacted.
B.
The same balance was used throughout the experiment.
C.
The students were careful in their measurements.
D.
The students were careful not to spill the contents.
The volume of Object X is approximately — A.
20 mL
B.
25 mL
C.
30 mL
D.
35 mL
V = 90 – 65 = 25
The following data were collected. The volume of the gas is known to be 2.20 L.
This data reflects — A.
low precision and low accuracy
B.
low precision and high accuracy
C.
low accuracy and high precision
D.
high accuracy and high precision
2C
4
H
10
+ 13O
2
8CO
2
+ 10H
2
O What is the mole ratio of C
4
H
10
CO
2
in the reaction shown?
to
A.
1:4
B.
2:13
C.
4:5
D.
13:8