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Talja [164]
4 years ago
10

a good sample of benzoic acid melts at 121-122. however, a student had a sample of benzoic acid that melted over a range, 105-11

5. what could the student concllude about his sample?
Chemistry
1 answer:
tatyana61 [14]4 years ago
8 0

Answer:

The student conclude that the sample of benzoic acid is impure.

Explanation:

The observed melting point of benzoic acid when a student melts his/her sample is low than the actual value. The reason for this might be:

(a) <u>The most probable reason is that the sample is impure. Impurities in the sample leads to lowering the value of the melting point.</u> The reason for the phenomenon is that when impurity is present in the compound, the pattern of the crystal lattice disturbs and thus it less amount of heat is require to break the lattice.

(b) There may be some experimental errors like:

  1. Non-uniform heating of the sample
  2. The sample is not tightly filled in the capillary if the student is    following Kjeldahl's flask method.
  3. If the student is using melting point machine, there there might be some instrumental errors.

<u>The student conclude that the sample is impure.</u>

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For the reaction of oxygen and nitrogen to form nitric oxide, consider the following thermodynamic data (Due to variations in th
CaHeK987 [17]

Answer:

a. 7278 K

b. 4.542 × 10⁻³¹

Explanation:

a.

Let´s consider the following reaction.

N₂(g) + O₂(g) ⇄ 2 NO(g)

The reaction is spontaneous when:

ΔG° < 0  [1]

Let's consider a second relation:

ΔG° = ΔH° - T × ΔS° [2]

Combining [1] and [2],

ΔH° - T × ΔS° < 0

ΔH° < T × ΔS°

T > ΔH°/ΔS°

T > (180.5 × 10³ J/mol)/(24.80 J/mol.K)

T >  7278 K

b.

First, we will calculate ΔG° at 25°C + 273.15 = 298 K

ΔG° = ΔH° - T × ΔS°

ΔG° = 180.5 kJ/mol - 298 K × 24.80 × 10⁻³ kJ/mol.K

ΔG° = 173.1 kJ/mol

We can calculate the equilibrium constant using the following expression.

ΔG° = - R × T × lnK

lnK = - ΔG° / R × T

lnK = - 173.1 × 10³ J/mol / (8.314 J/mol.K) × 298 K

K = 4.542 × 10⁻³¹

7 0
3 years ago
Which sentence correctly explains the process and conditions needed for sleet to form?
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Answer:Sleet only happens under very specific weather conditions. There must be a layer of air near the ground whose temperature is below freezing, where water turns to ice. Above this layer of freezing air must be a layer of warmer air. As snow falls through the warm air, it melts or partially melts into raindrops.

Explanation:

3 0
3 years ago
A lead atom has a mass of 3.14 x 10 to the negative 22nd g.How
frozen [14]

Explanation:

The given data is as follows.

       Mass of a lead atom = 3.14 \times 10^{-22}

       Volume = 2.00 cm^{3}

        Density = 11.3 g/cm^{3}

As it is mentioned that 1 cubic centimeter contains 11.3 grams of lead.

So, in 2 cubic centimeter there will be 2 \times 11.3 g = 22.6 g of lead atoms.

One lead atom has a mass of 3.14 \times 10^{-22}. Therefore, number of atoms present in 22.6 g of lead will be as follows.

                \frac{22.6 g}{3.14 \times 10^{-22}}

                  = 7.197 \times 10^{22} atoms

Thus, we can conclude that there are 7.197 \times 10^{22} atoms of lead are present.

4 0
3 years ago
CO is a primary pollutant.
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True

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Depending on the source of emission, pollutants can be classified into two groups that is primary and secondary pollutants.

A primary pollutant is emitted in the atmosphere directly from a source. It can be either natural sch as volcanic eruptions, sandstorms or man-made that is due to industrial and vehicle emissions.  Examples of primary pollutants are nitrogen oxides, carbon monoxide and particulate matter.

Secondary pollutant is due to interactions between primary and secondary pollutants. These can be chemical or physical interactions. Examples are photo-chemical oxidants and secondary particulate matter.

Therefore, carbon monoxide CO is a primary pollutant.





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B.) Because they both are Acids

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