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Rainbow [258]
3 years ago
8

Give two reasons why the flame test is sometimes invalid

Chemistry
2 answers:
Harlamova29_29 [7]3 years ago
7 0

Answer: 1.A false positive and 2.A false negative.

Explanation:

A false positive the classic example is the contamination of almost any sample with sodium ions which gives an intense yellow line even when the sodium is present as only impurity.

A false negative here sodium ions is the culprit that masks other emissions unless the emissions are resolved spectroscopically rather than simply visually.

zlopas [31]3 years ago
6 0
The two reason behind the invalidity of flame test are false positive and false negative.
while performing the flame test you must have to be accurate otherwise you will get false results may be positive for some element or may be negative in case the element is present. The main reason to get the false positive and false negative is the presence and contamination of sodium.
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Answer:

A homogeneous mixture has the same uniform appearance and composition throughout. Many homogeneous mixtures are commonly referred to as solutions. A heterogeneous mixture consists of visibly different substances or phases. The three phases or states of matter are gas, liquid, and solid.

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Answer: The answer to the first one is the second option and the answer for the second one is the first option.

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3 years ago
All energy originates from the _______.
Phantasy [73]

Answer:

sun

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3 years ago
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Copper has two naturally occurring isotopes. Cu−63 has a mass of 62.939 amu and relative abundance of 69.17%.
fiasKO [112]
The answer is 64.907 amu.

The atomic mass of an element is the average of the atomic masses of its isotopes. The relative abundance of isotopes must be taken into consideration, therefore:
atomic mass of copper = atomic mass of isotope 1 * abundance 1 + atomic mass of isotope 2 * abundance 2

We know:
atomic mass of copper = 63.546 amu
The atomic mass of isotope 1 is: 62.939 amu
The abundance of isotope 1 is: 69.17% = 0.6917
The atomic mass of isotope 1 is: x
The abundance of isotope 2: 100% - 69.17% = 30.83% = 0.3083

Thus:
63.546 amu = 62.939 amu * 0.6917 + x * 0.3083
63.546 <span>amu = 43.535 amu + 0.3083x
</span>⇒ 63.546 amu - 43.535 amu = 0.3083x
⇒ 20.011 amu = 0.3083x
   ⇒ x = 20.011 amu ÷ 0.3083 = 64.907 amu
7 0
3 years ago
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