autifu derful d perso ou know 6. a) Using your own data, is it possible to evaluate the ideas of Proust and Berthollet? e your d Aired st pot ad a b)...
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Can you please these questions?


d.jpeg

autifu
derful
d perso
ou know
6. a) Using your own data, is it possible to evaluate the ideas of Proust and Berthollet?
e your d
Aired
st
pot
ad a
b) Using the results of the entire class as the basis for your answer, can you decide whose hypothesis is
supported -- Berthollet's or Proust's? Explain.
7. The sample calculation for iron oxide in the IDEAS section of this experiment used known atomic
weights to calculate an empirical formula. However, early chemists did not have any references in
which they could look up atomic weights. Instead, they guessed at the formulas of compounds and
measured the percent compositions of elements in compounds in order to calculate atomic weights.
Calculate an atomic weight for iron using the hypothetical formula Fe101 and the composition data
given in the example in the IDEAS section. You may assume the atomic weight of oxygen is known from
other sources to be 16 amu, -> 2 sig tugs
Te : 0-7 1:1
1 x 16 9 0 = 16 grams
16
48
1 x X , Fe = X grams
X
112
Molar of = 2
3 x 16
48
X = 37. 33
ratio
2X 56
1127
round to 2sf
atomic weight of Fe is 37 g
8. In working the last problem, you may have noticed that a known atomic weight for oxygen was
required. Early chemists had no one to tell them the atomic weight of oxygen. They could have
proposed that the atomic weight of oxygen be set equal to 1.00 amu in order to calculate an atomic
weight of iron relative to that of oxygen. Use the same information as before and calculate the atomic
O : Fe
weight of iron relative to that of oxygen using the hypothetical formula Fe101. 3 gigs
0.86 9 Oxgen
atomic weighte = x
3:2
reacts w / 2 9 Iron
atomic weight oxJen = 1.00
0. 86
3
3 x
2 x 2
X
* = 201.55 )
201.55 ) = 3x
SA
oxygen
iron
3
X= 1.03 amu
2.58 = 4
2.58 x = 4
74
X = 1.55

h.jpeg

THOUGHT
1. Why is strong heating necessary at the end of the experiment?
Strong heating is necessary at the end of the
experiment to so that
water is evaporated.
all of the deionized
and Physics.
2. This question may require information of the kind that can be found in the Handbook of Chemistry
a. Is there more than one compound of magnesium and oxygen? If so, indicate the formulas of those
compounds containing only magnesium and oxygen.
yes Mgo - Magnesium oxide
Mgo2 - Magnesium peroxide
b. The maximum temperature attainable in the crucible on strong heating with a bunsen burner is
approximately 800 .C. Can the magnesium evaporate under the conditions of this experiment? Why or
add
why not?
move
NO, My will not evaporate completely under the conditions of this
experiment. The reason is because-ine boiling point
of magnesium is 1090 % and the melting point is 650-C. My will not
evaporate be cause its boiling point is too high (even though under 300"C it starts
3. Consider the following statements and describe the effect of each on the calculated percent to melt
magnesium in the sample (i.e. high, low, or no effect on the percent magnesium in the oxide). In each of
case, give a short explanation of your reasoning.
evagargle )
a. All of the magnesium does not burn.
All of the my doesn't burn because some of the
My will react with the Ne present in the air to form Mg 3 Nz
(3 Mg + N 2 -> Ng 3 NZ]. The Rest of the My will react with oxygen to
form Mgo.
b. The reaction smokes for a brief period. (Consider what the smoke is due to.)
c. All the magnesium nitride is not converted ultimately to magnesium oxide.
72

s.jpeg

ACTIVITIES
e for y
Is that
eautify
iderful
ad perso
you know
e your d
direc
Rachel Aronov
9/21
st
pot
d. All the water is not removed from the end product.
ad a
PEI
e. Some of the product is lost by spattering.
4. a. Report the average percent magnesium using all the values of the class.
68
used
b. What is the range of values? highest -lowest
62, 46,67, 68,69, 70, 72
42 - 62
figs
c. Calculate the standard deviation.
2. 2
5. Construct the bar graph of the class results as described in the INVESTIGATION section.
a. On the graph, mark the bars representing the most frequent value, the average value, and the
accepted value.
b. Are these three values the same when considered to 2 significant figures?
c. Is there evidence for either random or systematic error? How do you know?
d. If there is evidence of systematic error, what do you suggest is the cause?
AW
73

y.jpeg

ACTIVITIES
NAME Rochel ANDnov
SECTION
DATE 9/21/19
Computer Analysis of Mgo
1. What is the accepted value for the % Mg in MgO?
Examine the distribution for your dass and the composite curve for all classes.
your class
composite
2 a) What is the mean value?
68.1
63.4
now
b) What is the most frequent walue?
70
63
SF
c) What is the standard deviation?
2.17
2. 6
3. In what ways does the composite data differ from your class data?
4. Does the pooling of results in this experiment yield an average % Mg in Mgo which is
closer to the accepted value than your class average?
5. Compare the precision obtained by your class to the precision obtained by the
composite of all classes. Discuss.
6. What conclusion can you draw from the analysis of the data in assessing whether this
laboratory procedure gives accurate results?

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