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3 years ago

Why was it important to have endothermic and exothermic processes in the building materials of your train?

1 answer:

5 0

Before, trains worked using the steam engine. Thus, it uses heat so it is crucial to apply heat balance. The steam engine absorbs energy during the stage of boiling water. So, this is the endothermic reaction. When the steam is used to work the piston, it has to release this energy through running the train. The excess energy is released as an exhaust to the chimney. This is the exothermic process because it releases energy to the surroundings.

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What is the formula of the chromium(iii) complex that contains two ammonia and four thiocyanate (scn−) ligands?

Nonamiya [84]

Answer is: formula of the complex is [Cr(NH₃)₂(SCN)₄]⁻.
This complex has negative charge (-1) because chromium (central atom or metal) has oxidation number +3, first ligand ammonia has neutral charge and second ligand thiocyanate has negative oxidation number -1:
+3 + 2·0 + 4·(-1) = -1.

4 0

3 years ago

Calcule a variação da entalpia dessa reação ( 2 NH3 (g) ---> CO(NH2)2 (s) + H2O (L) ) a partir das seguintes equações termoqu

Nitella [24]

ΔH = +438 kJ

We have three equations:

(I) N₂ + 3H₂ → 2NH₃; ΔH = -92 kJ

(II) H₂ +½O₂ → H₂O; ΔH = -286 kJ

(III) CO(NH₂)₂ + ³/₂O₂ → CO₂ + 2H₂O + N₂; ΔH = -632 kJ

From these, we must devise the target equation:

(IV) 2NH₃ + CO₂ → CO(NH₂)₂ + H₂O; ΔH = ?

_________________________________

The target equation has 2NH₃ on the left, so you reverse equation (I).

When you reverse an equation, you reverse the sign of its ΔH.

(V) 2NH₃ → N₂ + 3H₂; ΔH = +92 kJ

Equation (V) has 1N₂ on the right, and that is not in the target equation.

You need an equation with 1N₂ on the left.

Reverse Equation (III).

(VI) CO₂ + 2H₂O + N₂ → CO(NH₂)₂ + ³/₂O₂; ΔH = +632 kJ

Equation (VI) has ³/₂O₂ on the right, and that is not in the target equation.

You need ³/₂O₂ on the left.

Multiply Equation (II) by three.

When you multiply an equation by three, you multiply its ΔH by three.

(VII) 3H₂ +³/₂O₂ → 3H₂O; ΔH = -286 kJ

Now, you add equations (V), (VI), and (VII), cancelling species that appear on opposite sides of the reaction arrows.

When you add equations, you add their ΔH values.

_______________________________________

We get the target equation (IV):

(V) 2NH₃ → N₂ + 3H₂; ΔH = + 92 kJ

(VI) CO₂ + 2H₂O + N₂ → CO(NH₂)₂ + ³/₂O₂; ΔH = +632 kJ

(VII) 3H₂ +³/₂O₂ → 3H₂O; ΔH = -286 kJ

(IV) 2NH₃ + CO₂ → CO(NH₂)₂ + H₂O; ΔH = +438 kJ

7 0

3 years ago

What is the energy of a photon with a frequency of 5.90 × 10¹⁴ s⁻¹? (h = 6.626 × 10⁻³⁴ J • s)

Licemer1 [7]

You use either the formula
E
=
h
f
or
E
=
h
c
λ
.

5 0

2 years ago

Which of the following interparticle forces is the weakest

GuDViN [60]

Answer:a

Explanation:sense

6 0

3 years ago

Read 2 more answers

How many ruthenium atoms can you line up across across the tip of a finger that is 3.6 cm in length. A ruthenium atom has an ave

Fofino [41]

Answer:

1.0 × 10⁸ ruthenium atoms

Explanation:

Step 1: Calculate the diameter (d) of an atom of ruthenium

The diameter of an atom is twice its radius.

d = 2 × r = 2 x 178 pm = 356 pm

Step 2: Convert "d" to meters

We will use the conversion factor 1 m = 10¹² pm.

356 pm × 1 m/10¹² pm = 3.56 × 10⁻¹⁰ m

Step 3: Convert the distance of the tip of a finger (D) to meters

We will use the conversion factor 1 m = 10² cm.

3.6 cm × 1 m/10² cm = 0.036 m

Step 4: Calculate the number of atoms of ruthenium required

We will use the following expression.

D/d = 0.036 m/3.56 × 10⁻¹⁰ m = 1.0 × 10⁸

4 0

3 years ago