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ANEK [815]
3 years ago
9

The following question was posed on an exam:

Chemistry
1 answer:
S_A_V [24]3 years ago
8 0

Answer:

The answer given by the student is not totally correct.

Explanation:

Law of multiple proportions states that an element Q will react with different volume of Fluorine to produce two non-similar compounds. Hence, the ratio of the masses(Fluorine only) needs to be an absolute reduced value.

Given that:

3.2 g of a sample of Q reacts with Fluorine to form 10.8 g of the unknown fluoride A.

This means the mass of Fluorine present in the compound = 10.8 g - 3.2 g = 7.6 g

Thus, 3.2 g of a sample of Q reacts with 7.6 g of Fluorine.

Also, 6.4 g sample of Q reacts with Fluorine to form 29.2 g of unknown fluoride B.

If we divide the samples by (2), we have 3.2 g sample of Q reacting with Fluorine to form 14.6 g of unknown fluoride B.

This means the mass of Fluorine present in the compound = 14.6 g - 3.2 g = 11.4 g

Thus, 3.2 g Q reacted here with 11.4 g fluorine.

Hence, 11.4/7.6 = 1.5 = 3/2

This above therefore satisfies the law of multiple proportions.

This is not aligned with what the student did, what the student did was to relate the amount of Q used to make A and B. Suppose, we start with twice amount of Q, the ratio would have been smaller(i.e. the ratio of Q).

So, this doesn't relate to the law of multiple proportions.

The law of multiple proportions is specifically concerned with the mass of the element rather than Q that can react with Q. Therefore, there is more reason to relate the two samples of equal masses of Q that react with different masses of Fluorine. The ratios of Fluorine will then be small whole numbers.

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If 20.0g of CO2 and 4.4g of CO2
Ksivusya [100]

The given question is incorrect. The correct question is as follows.

If 20.0 g of O_{2} and 4.4 g of CO_{2}  are placed in a 5.00 L container at 21^{o}C, what is  the pressure of this mixture of gases?

Explanation:

As we know that number of moles equal to the mass of substance divided by its molar mass.

Mathematically,   No. of moles = \frac{\text{mass}}{\text{molar mass}}

Hence, we will calculate the moles of oxygen as follows.

       No. of moles = \frac{\text{mass}}{\text{molar mass}}

     Moles of O_{2} = \frac{20.0 g}{32 g/mol}

                            = 0.625 moles

Now,   moles of CO_{2} = \frac{4.4 g}{44 g/mol}

                                      = 0.1 moles

Therefore, total number of moles present are as follows.

Total moles = moles of O_{2} + moles of CO_{2}

                    = 0.625 + 0.1

                    = 0.725 moles

And, total temperature  will be:

                    T = (21 + 273) K = 294 K

According to ideal gas equation,  

                         PV = nRT

Now, putting the given values into the above formula as follows.

                P = \frac{nRT}{V}

                   = \frac{0.725 mol \times 0.08206 Latm/mol K \times 294 K}{5.00 L}

                    = \frac{17.491089}{5} atm

                    = 3.498 atm

or,                = 3.50 atm (approx)

Therefore, we can conclude that the pressure of this mixture of gases is 3.50 atm.

4 0
3 years ago
(7th grade science question)
Akimi4 [234]
The most accurate way to measure a dry ingredient like flour, sugar or chocolate chips is in terms of its weight, which is measured in regular ounces.
7 0
3 years ago
3 H2 (g) + N2 (g) 2 NH3 (g)
ale4655 [162]

Answer:

Mass = 0.697 g

Explanation:

Given data:

Volume of hydrogen = 1.36 L

Mass of ammonia produced = ?

Temperature = standard = 273.15 K

Pressure = standard = 1 atm

Solution:

Chemical equation:

3H₂ + N₂       →      2NH₃

First of all we will calculate the number of moles of hydrogen:

PV  = nRT

R = general gas constant = 0.0821 atm.L/mol.K

1atm ×1.36 L = n × 0.0821 atm.L/mol.K × 273.15 K

1.36 atm.L = n × 22.43 atm.L/mol

n = 1.36 atm.L / 22.43 atm.L/mol

n = 0.061 mol

Now we will compare the moles of hydrogen and ammonia:

                 H₂         :          NH₃

                  3          :            2

                0.061     :         2/3×0.061 = 0.041

Mass of ammonia:

Mass = number of moles × molar mass

Mass = 0.041 mol × 17 g/mol

Mass = 0.697 g

4 0
3 years ago
Choose ALL TRUE statements about calorimetry from the choices below:
Ostrovityanka [42]

Answer:

True statment

2) Styrofoam would make a good calorimeter

3) Insulating material would make a good calorimeter

Explanation:

The calorimeter is one which is insulated that is which will not absorb or let the heat to escape from it. the calorimeter is used to measure the heat change during a process so if it will allow to exchange heat with surrounding it will deviate the readings or observence.

Copper is a good conductor of heat so we cannot use it make a calorimeter.

Hence

1) Copper would make a good calorimeter : False

2) Styrofoam would make a good calorimeter: True

Styrofoam is a bad conductor or insulator so it can be and it is used for calorimeter.

3) Insulating material would make a good calorimeter : True

4) A good calorimeter should easily absorb heat : false

6 0
3 years ago
How many atoms or moles of each element are on either side of the yield arrow? Is this equation balanced? 2Na+H2O---> NaOH+2H
Anton [14]
4 NA+4H2O —> 4NaOH+2H2

I hope that helped
4 0
3 years ago
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