<span><span>Terms of good sample
</span>In general, a good sample is which can represent as much as possible the characteristics of the population. In the language of measurement, meaning that the sample must be valid, which can measure something that should be measured. <span>A valid sample is determined by two considerations.
</span>First: The accuracy or precision, the degree of absence of "bias" (error) in the sample. In other words, the less the error rate is in the sample, the more accurate the sample. <span>Benchmarks for "bias" or error is population.
</span><span>Cooper and Emory (1995) states that "there is no systematic variance"
that means is there is no diversity of measurement due to the influence
of known or unknown, which led to scores tend to lead to a certain
point.
</span>Second: Precision. The second criterion is to have a good sample estimate of the level of precision. Precision refers to the question of how close we are to estimate population characteristics. There has never been a sample that can fully represent the characteristics of the population. Therefore,
in each sampling always attached keasalahan-error, which is known as
"sampling error" Precision is measured by standard deviation (standard
error). The
smaller the difference between the standard deviation obtained from the
sample (S) with a standard deviation of the population (s), the higher
the level of precision. Though
not always, the level of precision may be increased by adding the
number of samples, the fault may be reduced if the number of samples
plus (Kerlinger, 1973).</span>
Explanation:
When we are using spoon, beaker, stirring rod and graduated cylinder then they directly come in contact with the chemical we are using. Hence, if they are not washed thoroughly then chemicals remain deposited over them.
As a result, when successive test are performed using the same contaminated apparatuses then we do not get the desired results.
Whereas distilled water in a spray bottle if poured without touching or coming in contact with any kind of chemicals.
Hence, we can conclude that spoon, beaker, stirring rod and graduated cylinder are the tools that could have become cross-contaminated during the experiment if you had not cleaned them carefully between successive tests.
Increase because of the higher the temp
2SO2 + O2 ------> 2SO3
1) M(SO2)= 32.0 + 2*16.0 = 64 g/mol
2) 100.0 g SO2 * 1 mol SO2/64 g SO2 = 1.5625 mol SO2
3) 2SO2 + O2 ------> 2SO3
2 mol 1 mol
1.5625 mol x mol
x= 1.5625/2=0.78125 ≈ 0.7813 mol O2
Answer: 0.7813 mol O2.