ANACHEM - PRELIM Flashcards
A step in the analytical process that involves
transforming the sample into something that
is appropriate for the analysis.
Sample Preparation
You are given a cube of pure copper. You
measure its density three times and the
values recorded are 7.97 g/cm, 9.01 g/cm,
9.36 g/cm. Copper’s accepted density is 8.96
g/cm. What is your percent error?
2%
(9.23±0.03 + 4.21±0.02)-3.26±0.06
Compute for the absolute certainty and %
relative uncertainty.
10.18±0.07; 0.7%
Process being used to obtain salt from ocean
water?
evaporation
What is 78,590 rounded to two significant
figures?
79000
Process that is commonly used to separate
colored substances from each other?
Chromatography
An apparatus in the laboratory that is
primarily used to guard against spillage
when pouring chemicals from one container
to another.
delivery funnel
Dylan is shooting dart pins at a target.
Which of the following demonstrates high
accuracy but low precision?
Dylan consistently hits around the target
but never hits the bullseye
Maya buys several boxes of test tubes. On
the package, it says that each box has 50 test
tubes. She opens the boxes and only one of
them has 50 test tubes inside, the other
boxes either have too many or too few. How
would you describe the box of test tube with
50 test tubes inside?
Accurate and precise
Method of separation being utilized for
mixture of iron and sulfur
magnetism
It is prepared by weighing out an appropriate
portion of a pure solid and dissolving it to a
measure volume of liquid.
stock solution
An experiment calls for measuring 30ml of
NaCl solution in a graduated cylinder. How
should the graduated cylinder be read?
Hunch down until your head is on the same
level as the table top, then look to make sure
the bottom of the meniscus is at 30ml
How close a measurement is to the true
value is
Accuracy
Which of the following is TRUE about
chromatography?
It is use to identify the nature of the
components of a given sample.
Simplify: 3.85 x 10^18 /7.35 x 10^36
5.24 x10^17
Good work practices in the laboratory
include
confining long hair and loose clothing
Why is volumetric flask considered as more
precise in measuring volume instead of a
beaker, Erlenmeyer flask etc.?
it only measures specific volume of liquid.
Simplify: 26.14/37.62 x 10^8(4.38 x 10^2)
3.04 x 10^10
Simplify: 9.24-1.342/2.3
3.43
Simplify: a^9b^14/(ab)^7
a^2b^7
Which of the following is TRUE about the
volume of solvent and moles of solute in a
diluted solution?
The increase in volume makes the solution
unsaturated while the moles of solute remain
constant.
Water can be separated from alcohol by
simple distillation because
They have different boiling points
Compute the absolute and % relative
uncertainty for the given and express the
answer to the correct number of significant
digits.
(91.3±1.0) (40.3±0.2)/ 21.2 ±0.943
174± 3; ±2%
Which list shows the numbers in order from
least to greatest?
3.8 x 10^-3, 8.3 x 10^-3, 3.8x 10^-2
Analysis that involves description and
illustrations that cannot be measured is
Qualitative
Which of the following could prevent
systematic error?
periodic calibration of instruments
There are () significant digits in the number
80,000.00
7
The following should be done when
measuring a mass of a substance EXCEPT:
always make sure that the draft shield/cover
is properly closed when measuring the mass.
You are trying to synthesize and important
organic compound in the lab and you need
exactly 9ml of chloroform for the next
reaction. Which measuring tool would be the
most accurate to measure that liquid?
10ml graduated cylinder
10ml graduated cylinder
500 cc
In filtration, what name is used to describe
the solid left in the filter paper?
residue
Simplify. (5.64x10^-7) (6.1x10^4). Write
your answer in scientific notation
3.4x10^-2
Write (x) (x) (x) (x) (x) in exponential form?
X^5
The pipette is 8.7 long
7 is the estimated digit
Part of the analytical balance that allows the
user to reset the weight on the scale.
TARE button
A student adds 6.00g of a solid to 30.0mL of
water. The solid has a molar mass of
72.0g/mol. What is the molar concentration
of the solution? (If necessary to the
calculation, assume that 1.00g of the solid
has a volume of 1mL)
2.78mol/L
Field of chemistry that deals with
instrumentation and quantifying matter.
Analytical Chemistry
Which of the following pipettes has a
graduation that ends before the tip?
Mohr
Method of chemical analysis that deals more
with weighing the mass of chemicals
substances.
gravimetric
Forgetting to TARE a balance is an example
of
Personal Error
Repeated measurements of a quantity can
reduce the effects of
random errors
When heating a liquid or solution in a test
tube over an open flame:
Heat it gently and point it away from
anyone nearby
If a measurement result has uncertainty then
it means that the measurement was not
performed correctly.
True
Method of separation that is used for
substances that are immiscible like oil and
water.
Extraction
Write the number 8.56 x 10^3 in standard
form
0.00856
A set of data are all close to each other, but
are not close to the actual value is
precise
Wet method is a qualitative analysis that
makes use of a solvent to dissolve the
sample before analyzing it. Which of the
following are examples of wet methods?
Both gravimetric and volumetric are wet
methods
You weigh a substance on a balance and it
measures 23.49. The estimated digit is
9
Why is ‘weighing by difference’ accurate
than direct weighing?
it eliminates systematic errors
The following are placed in a beaker
weighing 41.568g: 3.798g of NaCl, 2.36g of
sand and 6.0g water. What is the final mass
of the beaker?
53.73g
The part of the mixture that passes through
the filter paper is the
filtrate
Find the absolute and percent relative
uncertainty and express your answer to the
correct number of digits.
(3.4±0.2 x 10^-8) ÷ (2.6± 0.1 x 10^-3)
1.3 ± 0.09x 10^-11; ±7%
If the beaker containing a sample of alcohol
weighs 50.9878g and the empty beaker
weighs 49.325g, what is the weight of the
alcohol?
1.663g
Write the number 0.964 in scientific
notation.
9.64 x 10^-1
Which of the following is best used for
storing and mixing liquids?
beaker
A blow out pipette
measures the volume of the last remaining
drop of liquid
A graduated cylinder upon measuring the
same sample three times gave 566mL,
584mL, and 541mL. The average of these
three values is 563.7mL. If the true value
was 563.688mL, how would you explain the
accuracy and precision of the
measurements?
The average value is accurate but the
individual values are neither accurate nor
precise
The following are the other sources of heat
inside the laboratory EXCEPT:
fire blanket
You need to prepare 250.0mL of a 2.50M
HCl solution using the stock solution 12.0M
HCl. What volume of 12.0M HCl is required
for this dilution?
52.1mL
