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Paha777 [63]
3 years ago
10

Please helppp :((((

Chemistry
2 answers:
Iteru [2.4K]3 years ago
7 0
<h3><u>Answer;</u></h3>

X is the effective nuclear charge, and it remains constant down a group.

<h3><u>Explanation</u>;</h3>
  • Effective nuclear charge is the actual nuclear charge (atomic number) minus the number of inner-core electrons which "shield" the valence electrons from feeling the full attraction.
  • Effective nuclear charge increases left to right across a period, because atomic number is increasing while inner-core electrons are constant .
  • The effective nuclear charge remains constant down a group, because atomic number increases, but so do the number of core electrons
garik1379 [7]3 years ago
5 0

Answer:

X is the screening constant, and it remains constant down a group.

Explanation:

It makes more sense and the core electrons are known as the shielding electrons, or screening constant. Usually when something is constant it remains consistent/unwavering.

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Based on the activity series, which metals could X represent in the reaction below? (Note: The equation is not balanced.)
Nikitich [7]
Answer is: A) Sr (strontium).
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3 0
4 years ago
The activation energy for a reaction is changed from 184 kJ/mol to 59.0 kJ/mol at 600. K by the introduction of a catalyst. If t
11111nata11111 [884]

Answer:

The catalyzed reaction will take 2.85 seconds to occur.

Explanation:

The activation energy of a reaction is given by:                                                        

k = Ae^{-\frac{E_{a}}{RT}}

For the reaction without catalyst we have:

k_{1} = Ae^{-\frac{E_{a_{1}}}{RT}}   (1)

And for the reaction with the catalyst:

k_{2} = Ae^{-\frac{E_{a_{2}}}{RT}}   (2)

Assuming that frequency factor (A) and the temperature (T) are constant, by dividing equation (1) with equation (2) we have:                      

\frac{k_{1}}{k_{2}} = \frac{Ae^{-\frac{E_{a_{1}}}{RT}}}{Ae^{-\frac{E_{a_{2}}}{RT}}}

\frac{k_{1}}{k_{2}} = e^{\frac{E_{a_{2}} - E_{a_{1}}}{RT}    

\frac{k_{1}}{k_{2}} = e^{\frac{59.0 \cdot 10^{3}J/mol - 184 \cdot 10^{3} J/mol}{8.314 J/Kmol*600 K} = 1.31 \cdot 10^{-11}    

Since the reaction rate is related to the time as follow:

k = \frac{\Delta [R]}{t}

And assuming that the initial concentrations ([R]) are the same, we have:

\frac{k_{1}}{k_{2}} = \frac{\Delta [R]/t_{1}}{\Delta [R]/t_{2}}

\frac{k_{1}}{k_{2}} = \frac{t_{2}}{t_{1}}

t_{2} = t_{1}\frac{k_{1}}{k_{2}} = 6900 y*1.31 \cdot 10^{-11} = 9.04 \cdot 10^{-8} y*\frac{365 d}{1 y}*\frac{24 h}{1 d}*\frac{3600 s}{1 h} = 2.85 s

Therefore, the catalyzed reaction will take 2.85 seconds to occur.

I hope it helps you!                            

4 0
3 years ago
In the process of eating, what kind of energy in food is transformed into heat energy by your body?
Rama09 [41]

Answer:The chemical energy

Explanation:because The chemical energy in the food you eat is changed into another kind of chemical energy that your body can use. Your body then uses that energy to give you the kinetic energy that you use in everything you do.

4 0
3 years ago
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Is the process represented below an example of a physical or a chemical
Basile [38]
It is a physical change because only the states as being changes, not the actual bonds in the compound.
6 0
3 years ago
Why is a terminal alkyne favored when sodium amide (NaNH2) is used in an elimination reaction with 2,3-dichlorohexane
mihalych1998 [28]

The question is incomplete, the complete question is;

Why is a terminal alkyne favored when sodium amide (NaNH2) is used in an elimination reaction with 2,3-dichlorohexane? product. A) The terminal alkyne is more stable than the internal alkyne and is naturally the favored B) The terminal alkyne is not favored in this reaction. C) The resonance favors the formation of the terminal rather than internal alkyne. D) The strong base deprotonates the terminal alkyne and removes it from the equilibrium.

E) The positions of the Cl atoms induce the net formation of the terminal alkyne.

Answer:

E) The positions of the Cl atoms induce the net formation of the terminal alkyne.

Explanation:

In this reaction, sterric hindrance plays a very important role. We know that sodamide is a strong base, it tends to attack at the most accessible position.

The first deprotonation yields an alkene. The strong base attacks at the terminal position again and yields the terminal alkyne. Thus the structure of the dihalide makes the terminal hydrogen atoms most accessible to the base. Hence the answer.

7 0
3 years ago
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