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1 year ago

Why is it important to compare the positive and negative test results with those of known compounds?

1 answer:

maks197457 [2]1 year ago

5 0

It is important to compare the positive and negative test results with those of known compounds as positive results indicate the presence of that known compound and negative results indicate the absence of that compound which is used for reference.

<h3>What is qualitative analysis?</h3>

Qualitative chemical analysis is a method to determine the chemical composition of a sample.

There are two types of qualitative analysis:

Organic Qualitative analysis: It helps in determining the chemical bonds and functional groups in a sample

Inorganic qualitative analysis: It helps in determining the ions in the given sample

There are seven ways to analyze a sample qualitatively, which are

Change in color

Flame test

Distillation

Extraction

Precipitation

Chromatography

Spectroscopy

A reference compound is always used to which results are compared.

A Positive result indicates that the reference compound is present in the sample whereas a negative result indicates that the reference compound is absent in the given sample.

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The average atomic mass of Eu is 151.96 amu. There are only two naturally occurring isotopes of europium, Eu with a mass of 151.

earnstyle [38]

Answer:

The percentage abundance of Eu isotopes are 52 % and 48 % .

Explanation:

The formula for the calculation of the average atomic mass is:

$Average\ atomic\ mass=(\frac {\%\ of\ the\ first\ isotope}{100}\times {Mass\ of\ the\ first\ isotope})+(\frac {\%\ of\ the\ second\ isotope}{100}\times {Mass\ of\ the\ second\ isotope})$

Given that:

Since the element has only 2 isotopes, so the let the percentage of first be x and the second is 100 -x.

For first isotope,:

% = x %

Mass = 151.0 amu

For second isotope :

% = 100 - x

Mass = 153.0 amu

Given, Average Mass = 151.96 amu

Thus,

$151.96=\frac{x}{100}\times {151.0}+\frac{100-x}{100}\times {153.0}$

Solving for x, we get that:

x = 52 %

<u>Thus percentage abundance of Eu isotopes are 52 % and 48 % .</u>

7 0

3 years ago

Give three examples of environmental, industrial and bio-chemistry.

JulsSmile [24]

Three examples of environmental, industrial and bio-chemistry are listed below:

Environmental chemistry: Contamination, Atmospheric Deposition, and Soil Pollution.
industrial chemistry: industrial inorganic chemicals, industrial organic chemicals, and agricultural chemicals
bio-chemistry: genetic, immunology, and enzymology

<h3>Meaning of Chemistry</h3>

Chemistry can be defined as a branch of science which is concerned with the substances matter is composed of, their properties and reactions,

Chemistry also deals with the use of such reactions to form new substances.

In conclusion, Three examples of environmental, industrial and bio-chemistry are listed anove

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4 0

2 years ago

Which layer of ground contains organic matter and tiny rock particles?

Ann [662]

Answer:

A Horizon - The layer called topsoil; it is found below the O horizon and above the E horizon. Seeds germinate and plant roots grow in this dark-colored layer. It is made up of humus (decomposed organic matter) mixed with mineral particles.

4 0

3 years ago

Bacteria reproduce using

nadya68 [22]

Answer:

Bacteria reproduce by binary fission. In this process the bacterium, which is a single cell, divides into two identical daughter cells. Binary fission begins when the DNA of the bacterium divides into two (replicates). ... Each daughter cell is a clone of the parent cell.

Explanation:

5 0

3 years ago

Analysis

Karolina [17]

The properties of substances can be used to put the into groups.

<h3>Grouping of substances</h3>

In chemistry, it is often necessary to put substances into groups based on similarity in their properties. This is what led to the idea of a periodic table of elements.

Similarly, when we have unknown substances, we can group them according to the similarities in their properties.

Learn more about properties of substances: brainly.com/question/19886211

6 0

2 years ago