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Alexeev081 [22]
3 years ago
12

How to determine how many valence electrons an element has?

Chemistry
1 answer:
In-s [12.5K]3 years ago
8 0
Usually (ignoring transition metals, as they kinda get trickier), the element's valency can be found out by its group (column) number. Usually, we ignore the transition metal block while counting these columns, so Aluminium is in group 3, for example. Since Aluminium is in group 3, it has 3 valence electrons.
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Concept Review<br> 14.11. Can a reaction that is not reversible achieve chemical equilibrium?
MakcuM [25]

Answer:

No

Explanation:

Chemical equilibrium is reached by the forward reaction rate equaling the reverse reaction rate. If the reaction is not reversible, this could not occur.

7 0
3 years ago
The balanced equation for combustion in an acetylene torch is shown below:
vichka [17]

Answer:

70mol

Explanation:

The equation of the reaction is given as:

                  2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O

Given parameters:

Number of moles of acetylene = 35.0mol

Number of moles of oxygen in the tank = 84.0mol

Unknown:

Number of moles of CO₂ produced = 35.0mol

Solution:

From the information given about the reaction, we know that the reactant that limits this combustion process is acetylene. Oxygen is given in excess and we don't know the number of moles of this gas that was used up. We know for sure that all the moles of acetylene provided was used to furnish the burning procedure.

To determine the number of moles of CO₂ produced, we use the stoichiometric relationship between the known acetylene and the CO₂ produced from the balanced chemical equation:

From the equation:

         2 moles of acetylene produced 4 moles of CO₂

          ∴ 35.0 mol of acetylene would produced:  

                               \frac{35 x 4}{2} = 70mol

6 0
2 years ago
Read 2 more answers
The number of protons plus the number of neutrons in an atom is called its 7 number. for carbon-12, this number is
emmasim [6.3K]
The mass of Carbon-12 is 12.
8 0
3 years ago
The compound Xe(CF3)2 decomposes in afirst-order reaction to elemental Xe with a half-life of 30. min.If you place 7.50 mg of Xe
Irina-Kira [14]

Answer:

t=147.24\ min

Explanation:

Given that:

Half life = 30 min

t_{1/2}=\frac{\ln2}{k}

Where, k is rate constant

So,  

k=\frac{\ln2}{t_{1/2}}

k=\frac{\ln2}{30}\ min^{-1}

The rate constant, k = 0.0231 min⁻¹

Using integrated rate law for first order kinetics as:

[A_t]=[A_0]e^{-kt}

Where,  

[A_t] is the concentration at time t

[A_0] is the initial concentration

Given that:

The rate constant, k = 0.0231 min⁻¹

Initial concentration [A_0] = 7.50 mg

Final concentration [A_t] = 0.25 mg

Time = ?

Applying in the above equation, we get that:-

0.25=7.50e^{-0.0231\times t}

750e^{-0.0231t}=25

750e^{-0.0231t}=25

x=\frac{\ln \left(30\right)}{0.0231}

t=147.24\ min

6 0
3 years ago
Is this molecule polar or nonpolar?
lutik1710 [3]
The answer is nonpolar  

3 0
2 years ago
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