Which observation does not indicate that a chemical reaction has occurred?

When nitrogen dioxide (NO2) from car exhaust combines with water in the air, it forms nitric acid (HNO3), which causes acid rain

yKpoI14uk [10]

<u>Answer:</u>

<u>For a:</u> The number of molecules of nitrogen dioxide is $4.52\times 10^{23}$

<u>For b:</u> The mass of nitric acid formed is 54.81 grams

<u>For c:</u> The mass of nitric acid formed is 206 grams

<u>Explanation:</u>

The given chemical reaction follows:

$3NO_2(g)+H_2O(l)\rightarrow 2HNO_3(aq.)+NO(g)$

<u>For a:</u>

By Stoichiometry of the reaction:

1 mole of water reacts with 3 moles of nitrogen dioxide

So, 0.250 moles of water will react with $\frac{3}{1}\times 0.250=0.75mol$ of nitrogen dioxide

According to mole concept:

1 mole of a compound contains $6.022\times 10^{23}$ number of molecules.

So, 0.75 moles of nitrogen dioxide will contain $0.75\times 6.022\times 10^{23}=4.52\times 10^{23}$ number of molecules

Hence, the number of molecules of nitrogen dioxide is $4.52\times 10^{23}$

<u>For b:</u>

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of nitrogen dioxide = 60.0 g

Molar mass of nitrogen dioxide = 46 g/mol

Putting values in equation 1, we get:

$\text{Moles of nitrogen dioxide}=\frac{60.0g}{46g/mol}=1.304mol$

By Stoichiometry of the reaction:

3 moles of nitrogen dioxide produces 2 mole of nitric acid

So, 1.304 moles of nitrogen dioxide will produce = $\frac{2}{3}\times 1.304=0.870$ moles of nitric acid

Now, calculating the mass of nitric acid from equation 1, we get:

Molar mass of nitric acid = 63 g/mol

Moles of nitric acid = 0.870 moles

Putting values in equation 1, we get:

$0.870mol=\frac{\text{Mass of nitric acid}}{63g/mol}\\\\\text{Mass of nitric acid}=(0.870mol\times 63g/mol)=54.81g$

Hence, the mass of nitric acid formed is 54.81 grams

<u>For c:</u>

<u>For nitrogen dioxide:</u>

Given mass of nitrogen dioxide = 225 g

Molar mass of nitrogen dioxide = 46 g/mol

Putting values in equation 1, we get:

$\text{Moles of nitrogen dioxide}=\frac{225g}{46g/mol}=4.90mol$

<u>For water:</u>

Given mass of water = 55.2 g

Molar mass of water = 18 g/mol

Putting values in equation 1, we get:

$\text{Moles of water}=\frac{55.2g}{18g/mol}=3.06mol$

By Stoichiometry of the reaction:

3 moles of nitrogen dioxide reacts with 1 mole of water

So, 4.90 moles of nitrogen dioxide will react with = $\frac{1}{3}\times 4.90=1.63mol$ of water

As, given amount of water is more than the required amount. So, it is considered as an excess reagent.

Thus, nitrogen dioxide is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

3 mole of nitrogen dioxide produces 2 moles of nitric acid

So, 4.90 moles of nitrogen dioxide will produce $\frac{2}{3}\times 4.90=3.27mol$ of nitric acid

Now, calculating the mass of nitric acid from equation 1, we get:

Molar mass of nitric acid = 63 g/mol

Moles of nitric acid = 3.27 moles

Putting values in equation 1, we get:

$3.27mol=\frac{\text{Mass of nitric acid}}{63g/mol}\\\\\text{Mass of nitric acid}=(3.27mol\times 63g/mol)=206g$

Hence, the mass of nitric acid formed is 206 grams

7 0

3 years ago

What is the percent composition by mass of chlorine in LiCI

Lelechka [254]

Answer: Lithium (Li) 16.373%

Chlorine (Cl) 83.627%

Explanation:

6 0

3 years ago

• identify early ideas about evolution

Andreyy89

There is two ideas about evolution.

1.) Religious
2.) Scientific

In the religious one, people believe that we were created through god.

In the scientific one, people believe that we were created from apes and that throughout time we became humans.

7 0

3 years ago

A container of gas has a volume of 3.5 L and a pressure of 0.8 atm. Assuming the temperature remains constant, what volume of ga

vovikov84 [41]

<h3>Answer:</h3>

5.6 L

<h3>Explanation:</h3>

We are given;

Initial volume, V1 = 3.5 L
Initial pressure, P1 = 0.8 atm
Final pressure, P2 = 0.5 atm

We are required to calculate the final volume;

According to Boyle's law, the volume of a fixed mass of a gas and the pressure are inversely proportional at a constant temperature.

That is; P α 1/V
Mathematically, P=k/V
At two different pressure and volume;

P1V1 = P2V2

In this case;

Rearranging the formula;

V2 = P1V1 ÷ P2

= (0.8 atm × 3.5 L) ÷ 0.5 atm

= 5.6 L

Therefore, the resulting volume is 5.6 L

7 0

3 years ago

Lexus.com/assessments/learnosity.aspx?idAssessment=1824894&idWebuser=4331214&idSection=1621362&idHtmllet=12178858&am

Kobotan [32]

From the relationship between wavelength and frequency, the frequency of the wave is reduced by half to 60 Hz as the wavelength is increased twice to 10 m at constant speed.

<h3>What is the relationship between wavelength, velocity and frequency of a wave?</h3>

The velocity, frequency and wavelength of a wave are related by the formula given below:

v = fλ

where

v is velocity
f is frequency
λ is wavelength of the wave

From the above relationship:

If the wavelength of a wave is increased to 10m but the speed stays the same at 600 m/s, the frequency can be calculated as follows:

f = v/λ

f = 600/10

f = 60 Hz

Therefore, the frequency of the wave is reduced by half as the wavelength is increased twice at constant speed.

Learn more about frequency and wavelength of a wave at: brainly.com/question/4386945

6 0

2 years ago