All categories

3 years ago

Can anyone explain this to me?

Chemistry

1 answer:

Kipish [7]3 years ago

5 0

The answer is D, the definition of standard enthalpy of formation is as follows: when one mole of a substance in the standard state (1 atm of pressure and 298.15 K) is formed from its pure elements. The last two words being especially important to this question. We would rule out A, B and C all because the product is formed from a mixture of an element and a compound and not just of elements. In other questions the reactants may all be in elemental form so you must look at the products being one mole or the reactants not being in their standard state.

You might be interested in

Can someone Summarize how the suns gravity affects the planets please.

egoroff_w [7]

The sun's gravity pulls the planet toward the sun, which changes the straight line of direction into a curve. This keeps the planet moving in an orbit around the sun. Because of the sun's gravitational pull, all the planets in our solar system orbit around it.

3 0

3 years ago

Read 2 more answers

If the change in entropy of the surroundings for a process at 451 k and constant pressure is -326 j/k, what is the heat flow abs

Arisa [49]

If the change in entropy of the surroundings for a process at 451 k and constant pressure is -326 j/k, then heat flow absorbed (in kj) by the system is -147.026kJ.

<h3>What is entropy? </h3>

The entropy of particle is defined as how random it move. It shows the randomness of the system or may be disorders of the system. It is used to measure the unavailable energy for performing useful work.

Unit of entropy = J/K

<h3>Formula:</h3>

∆s = ∆Q/T

where,

∆s = change in entropy of the surrounding = -326J/K

∆Q = heat absorbed from surrounding

T = Temperature = 451K

∆Q = ∆s × T

∆Q = -326 × 451

∆Q = 147,026 J

∆Q = 147.026 kJ

Thus we find that the heat absorbed by the system is 147.026 kJ.

learn more about entropy:

brainly.com/question/14131507

#SPJ1

8 0

2 years ago

How many ions are there in 0.187 mol of Na+ ions

kondaur [170]

Best Answer
1 mole of a substance contains 6.022x10^23 "units" of that substance.

So 0.187 mol of Na+ is 1.13x10^23 ions (6.022x10^23 x 0.187).

4 0

4 years ago

Read 2 more answers

What's it called when an electron has absorbed alot of energy?

emmainna [20.7K]

Answer:

Excited state

Explanation:

Excited state is the name of the state when electrons absorb energy and move to a higher energy level.

Hope this helps!

8 0

3 years ago

Ammonia and oxygen react to produce nitric oxide and water. Which of the following chemical equations describes this reaction an

aksik [14]

Answer:

Option B. 4NH3(g) + 5O2(g) —> 4NO(g) + 6H2O(g)

Explanation:

The reaction between ammonia, NH3 and oxygen, O2, will produce nitric oxide and water as shown below:

NH3(g) + O2(g) —> NO(g) + H2O(g)

Now, let us balance the equation.

This is illustrated below:

NH3(g) + O2(g) —> NO(g) + H2O(g)

There are 3 atoms of H on the left side and 2 atoms on the right side. It can be balance by putting 4 in front of NH3 and 6 in front of H2O as shown below:

4NH3(g) + O2(g) —> NO(g) + 6H2O(g)

There are 4 atoms of N on the left side and 1 atom on the right side. It can be balance by putting 4 in front of NO as shown below:

4NH3(g) + O2(g) —> 4NO(g) + 6H2O(g)

Now, the are 2 atoms of O on the left side and a total of 10 atoms on the right side. It can be balance by putting 5 in front of O2 as shown below:

4NH3(g) + 5O2(g) —> 4NO(g) + 6H2O(g)

Now, we can see that the equation is balanced.

Therefore, option B gives the balanced chemical equation for the reaction.

5 0

3 years ago