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PSYCHO15rus [73]
1 year ago
10

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

Chemistry
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.

Learn more about qualitative analysis:

brainly.com/question/1779681

#SPJ4

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How many atoms of lodine(I) are in 0.156 grams of I?
CaHeK987 [17]

Answer: iodine 131 iodine 132 isotopes

Explanation:

4 0
3 years ago
Hydrofluoric acid and Water react to form fluoride anion and hydronium cation, like this HF(aq) + H_2O(l) rightarrow F(aq) + H_3
maksim [4K]

Answer:

Kc = 1.09x10⁻⁴

Explanation:

<em>HF = 1.62g</em>

<em>H₂O = 516g</em>

<em>F⁻ = 0.163g</em>

<em>H₃O⁺ = 0.110g</em>

<em />

To solve this question we need to find the moles of each reactant in order to solve the molar concentration of each reactan and replacing in the Kc expression. For the reaction, the Kc is:

Kc = [H₃O⁺] [F⁻] / [HF]

<em>Because Kc is defined as the ratio between concentrations of products over reactants powered to its reaction coefficient. Pure liquids as water are not taken into account in Kc expression:</em>

<em />

[H₃O⁺] = 0.110g * (1mol /19.01g) = 0.00579moles / 5.6L = 1.03x10⁻³M

[F⁻] = 0.163g * (1mol /19.0g) = 0.00858moles / 5.6L = 1.53x10⁻³M

[HF] = 1.62g * (1mol /20g) = 0.081moles / 5.6L = 0.0145M

Kc = [1.03x10⁻³M] [1.53x10⁻³M] / [0.0145M]

<h3>Kc = 1.09x10⁻⁴</h3>
7 0
3 years ago
Which type of radioactive decay produces
sladkih [1.3K]
Which type of radioactive decay produces particles with the most mass? Alpha.
6 0
3 years ago
Calculate the delta S rxn at 25 degrees celsius for the reaction 2NH3(g)-&gt;&gt;N2H4(g) + H2(g). Do you know where I can find t
Alchen [17]
In order to find your answer you need to be <span>measuring entropy, so you will be using the following formula:
</span><span>delta S= S of (N2H4) + S of ( H2) - [2( S of NH3)]
</span>Hope this is very useful for you
3 0
3 years ago
) Starting with 5.00 g barium chloride n hydrate yields 4.26 g of anhydrous barium chloride after heating. Determine the integer
RSB [31]

Answer:

2

Explanation:

Mass of water molecule = mass of hydrated salt - mass of anhydrous salt

Mass of water molecule = 5.00 - 4.26 = 0.74g of water molecule.

Number of moles = mass / molarmass

Molar mass of water = 18.015g/mol

No. of moles of water = 0.74 / 18.015 = 0.0411 moles.

Mass of BaCl2 present =?

1 mole of BaCl2 = 208.23 g

X mole of BaCl2 = 4.26 g

X = (4.26 * 1) / 208.23

X = 0.020

0.020 moles is present in 4.26g of BaCl2

Mole ratio between water and BaCl2 =

0.0411 / 0.020 = 2

Therefore 2 molecules of water is present the hydrated salt.

4 0
3 years ago
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