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3 years ago

Which of the following has a central atom that exceeds the octet rule? PCl5 BeF2 H2S CO2

1 answer:

7 0

Schwarzschild Radius here.

So,

The octet rule really only holds up for the second period elements, and only certain elements in that period, for that matter. Elements in the third periods and beyond can have expanded octets.

Draw Lewis dot diagrams for each molecule.

$PCl_5$ :

P is the central atom bonded individually to each Cl. The only logical diagram is that with three lone pairs surrounding each Cl and the P single-bonded to each Cl atom. If you count the bonds, you will find that P has five pairs, or 10 electrons. This exceeds the octet rule.

$BeF_2$ :

The Lewis dot diagram for this molecule is a linear molecule with the Be in the center, singly bonded to both F's, each of which have three lone pairs. This means Be has only two pairs, or four electrons. While not an example of a central atom that exceeds the octet rule, Be is one of the special elements that can stably have an incomplete octet.

$H_{2}S$ :

The most stable diagram for this molecule is with S in the center with two lone pairs and singly bonded to each H atom. With four pairs, or 8 electrons, this molecule obeys the octet rule.

$CO_2$ :

The diagram for this molecule is C in the center doubly bonded to each O atom. Each O atom has 2 lone pairs. C has four pairs, or 8 electrons. This molecule also obeys the octet rule.

Hope this helps!

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For a particular reaction, ΔH=−111.4 kJ/mol and ΔS=−25.0 J/(mol·K).

PtichkaEL [24]

That’s the answer ^^^^

3 0

3 years ago

What is meant by the limiting reactant why is it necessary to identify the limiting reactant when you want to know what?

WARRIOR [948]

You have the reactants who react to make your products.

Reactants --------> Products

The limiting reactant is the reactant that will RUN OUT FIRST and that will establish the maximum amount of product that will be produced.

To make an example, let's look at this equation and at the following question:

2Al + 6HCl → 2AlCl3 + 3H2

When 6.0 mol Al react with 13 mol HCl, what is the limiting reactant, and how many moles of H2 can be formed?

We know that 2Al + 6HCL are the reactants, right?

These 2 reactants will react to create an amount of a certain product in this case they're asking us for the amount of H2 that will be produced. Therefore, we need to find the REACTANT it can be either AL OR HCL.

But, how do we know which one is the limiting reactant?

To know which one is the limiting reactant we need to know HOW MUCH H2 can Al produce, and also how much H2 can HCL produce. Why?

It's simple, because if you find the one that produces the less amount of H2, you know immediately that's the maximum amount of that product that will be produced.

Let's say you have a sandwich that needs to be made with 2 slices of bread, 3 meats and 1 cheese.

But you have got 4 slices of bread, 9 slices of meat, and 5 slices of cheese.

Well, you could make 2 sandwiches with 4 slices of bread, 3 sandwiches with those 9 slices of meat and 5 sandwiches with the 5 slices of cheese.

But, in reality, you can only make 2 sandwiches because you don't have any more bread to produce more sandwiches. You get it? That is the point of limiting reactants, to find what is the actual amount that can be produced.

Coming back to our equation, we can find the number of moles of H2 produced by each one of the reactants, Al and HCl. I'll find the number of moles quickly to show you what the concept of limiting reactant is.

6.0mol Al x 3 mol H2/2 mol Al = 9 mol H2

13 mol HCL x 3 mol H2/6 mol HCL = 6.5 mol H2

As you can see, 6.5 mol of H2 is the maximum that can be produced by the HCL and is less than the Al, so that maximum amount that you will get in the product H2 is no more than 6.5.

4 0

3 years ago

How many solutions does the equation (3x + 7) = -4 have?<br>B. one<br>C. WO<br>D. infinitely many

Eddi Din [679]

Answer:

Its One

Explanation:

hope it helps!

mark me brainliest :))

8 0

3 years ago

Which solution has a molality of 0.25m nacl?

Solnce55 [7]

Molality can be expressed by moles of solute over kilograms of solvent. The question asks the molality of 0.25m NaCl. 0.25m NaCl is equal to 0.25 moles of NaCl over 1 kg of water.

5 0

3 years ago

Read 2 more answers

Which of the following statements is typically true for a catalyst? I. The concentration of the catalyst will go down as a react

gladu [14]

Answer: II. The catalyst provides a new pathway in the reaction mechanism.

III. The catalyst speeds up the reaction.

Explanation:

Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.

A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and more molecules convert to products.

The catalyst itself does not take part in the chemical reaction and gets regenerated as such at the end of the reaction without getting consumed.

3 0

3 years ago