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Marta_Voda [28]
1 year ago
5

Check my answers please? 1. Which of the following is a correctly written thermochemical equation? NH4Cl NH4+ + Cl 2C8H18 + 25O2

16CO2 + 18H2O, H = 5,471 kJ/mol Fe (s) + O2 (g) Fe2O3 (s), H = 3,926 kJ -->C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (l), H = 2,220 kJ/mol 2. How does a phase change affect a thermochemical equation? It alters the moles of reactants. -->It can affect the (delta) H value. It alters the products. It affects the balance of the equation. 3. For the reaction CH4 (g) + 2O2 (g) CO2 (g) + 2H2O (l), H = 890 kJ, what will be the change in enthalpy when 3 moles of methane react in excess oxygen?
890 kJ

-->2.67 × 103 kJ

+890 kJ

+2.67 × 103 kJ

4. In which of the following thermochemical equations would the H be considered a heat of solution?

NH4Cl (s) NH4+ (aq) + Cl (aq), H = + 14.8 kJ/mol

2C8H18 (l) + 25O2 (g) 16CO2 (g) + 18H2O (l), H = 5,471 kJ/mol

-->4Fe (s) + 3O2 (g) 2Fe2O3 (s), H = 3,926 kJ

C3H8 (g) + 5O2 (g) 3CO2 (g) + 4H2O (l), H = 2,220 kJ/mol

5. For the following reaction at STP, how much heat will be required to produce 63 L of NO? (At STP, one mole of any gas occupies 22.4 L.)

N2 (g) + O2 (g) 2NO (g), H = 180.5 kJ

+63 kJ

+127 kJ

-->+254 kJ

+508 kJ
Chemistry
1 answer:
snow_tiger [21]1 year ago
4 0
1. I think you chose the right answer, the equation has the states of the reactants and products. 2. I think you chose the right answer. 3. I think you also chose the right answer. Assuming that the Hrxn is written as kJ per mol CH4 4. Heat of solution is the enthalpy change associated with dissolving a solute in a solvent. I think the first choice is the right one. 5. I think you chose the right answer.
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When small pieces of manganese oxide were added to a solution of hydrogen peroxide, water and oxygen were produced. Manganese ox
Vikki [24]

Answer: In the given reaction increasing the amount of solution is likely to increase the rate of the reaction.

Explanation:

It is known that more is the number of reactant molecules taking part in a chemical reaction more will be the number of collisions occur. As a result, more will be the rate of chemical reaction.

For example, When hydrogen peroxide dissociates into water and oxygen on addition of manganese oxide then increasing the number of reactants (hydrogen peroxide and manganese oxide) will also lead in the increase in rate of reaction.

Thus, we can conclude that in the given reaction increasing the amount of solution is likely to increase the rate of the reaction.

4 0
2 years ago
A certain radioactive atom has 90 protons and 142 neutrons. If this atom undergoes alpha decay, what is the mass number of the d
Hatshy [7]

Answer: the mass number of the daugther atom is 232,


Explanation:


1) Alpha (α) decay is a nuclear reaction in which a nucleus (parent's nucleus) emits an alpha (α) particle and leads to a different atom (daughter atom).


2) The alpha (α) particle is a nucleus of helium atom, i,e, a nucleus with two protons and two neutrons. The symbol used for the α particles is <em>⁴₂He</em>, where the superscript 4 indicates the mass number (2 protons + 2 neutrons = mass number 4), and the subscript 2 indicates the atomic number (number of protons).


3) Then, to determine the mass number of the daughter atom you just need to do a mass number balance:


mass number of the parent atom = mass number of the daugther atom + mass number of the α particle.


The mass number of the radioactive (parent) atom is 90 protons + 142 neutrons = 232.


∴ 232 = x + 4 ⇒ x = 232 - 4 = 228 ← answer.


The full equation may help you to have a wider vision of the problem:


²³²₉₀ X → ⁴₂ He + ²²⁸₈₈ Y

Note this:

  • 232 = 4 + 228 (this is a mass number balance)
  • 90 = 2 + 88 (this is an atomic number balance)
  • X is the parent atom, and Y is the daughter atom
  • You can use a periodic table to determine the identity of the unknown atoms (using the atomic numbers).
5 0
2 years ago
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Which would be a more practical source of electricity for a car: a wet cell or a dry cell? Why?
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Answer:

wet

Explanation:

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2 years ago
When uranium-235 atoms undergo fission, ________ is/are produced?
elena-s [515]
Smaller atoms ; free neutrons and energy
8 0
1 year ago
Ammonia gas is compressed from 21°C and 200 kPa to 1000 kPa in an adiabatic compressor with an efficiency of 0.82. Estimate the
Evgen [1.6K]

Explanation:

It is known that efficiency is denoted by \eta.

The given data is as follows.

     \eta = 0.82,       T_{1} = (21 + 273) K = 294 K

     P_{1} = 200 kPa,     P_{2} = 1000 kPa

Therefore, calculate the final temperature as follows.

         \eta = \frac{T_{2} - T_{1}}{T_{2}}    

         0.82 = \frac{T_{2} - 294 K}{T_{2}}    

          T_{2} = 1633 K

Final temperature in degree celsius = (1633 - 273)^{o}C

                                                            = 1360^{o}C

Now, we will calculate the entropy as follows.

       \Delta S = nC_{v} ln \frac{T_{2}}{T_{1}} + nR ln \frac{P_{1}}{P_{2}}

For 1 mole,  \Delta S = C_{v} ln \frac{T_{2}}{T_{1}} + R ln \frac{P_{1}}{P_{2}}

It is known that for NH_{3} the value of C_{v} = 0.028 kJ/mol.

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

     \Delta S = C_{v} ln \frac{T_{2}}{T_{1}} + R ln \frac{P_{1}}{P_{2}}

                = 0.028 kJ/mol \times ln \frac{1633}{294} + 8.314 \times 10^{-3} kJ \times ln \frac{200}{1000}

                = 0.0346 kJ/mol

or,             = 34.6 J/mol             (as 1 kJ = 1000 J)

Therefore, entropy change of ammonia is 34.6 J/mol.

3 0
1 year ago
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