In a Lewis structure for carbon tetrachloride (CCl4), which of the following is the central atom?

bagirrra123 [75]

$176.0 \; \text{kJ} \cdot \text{mol}^{-1}$

As long as the equation in question can be expressed as the sum of the three equations with known enthalpy change, its $\Delta H$ can be determined with the Hess's Law. The key is to find the appropriate coefficient for each of the given equations.

Let the three equations with $\Delta H$ given be denoted as (1), (2), (3), and the last equation (4). Let $a$ , $b$ , and $c$ be letters such that $a \times (1) + b \times (2) + c \times (3) = (4)$ . This relationship shall hold for all chemicals involved.

There are three unknowns; it would thus take at least three equations to find their values. Species present on both sides of the equation would cancel out. Thus, let coefficients on the reactant side be positive and those on the product side be negative, such that duplicates would cancel out arithmetically. For instance, $3 + (-1) = 2$ shall resemble the number of $\text{H}_2$ left on the product side when the second equation is directly added to the third. Similarly

$\text{NH}_4 \text{Cl} \; (s)$ : $-2 \; a = 1$
$\text{NH}_3\; (g)$ : $-2 \; b = -1$
$\text{HCl} \; (g)$ : $2 \; c = -1$

Thus

$a = -1/2\\b = 1/2\\c = -1/2$ and

$-\frac{1}{2} \times (1) + \frac{1}{2} \times (2) - \frac{1}{2} \times (3)= (4)$

Verify this conclusion against a fourth species involved- $\text{N}_2 \; (g)$ for instance. Nitrogen isn't present in the net equation. The sum of its coefficient shall, therefore, be zero.

$a + b = -1/2 + 1/2 = 0$

Apply the Hess's Law based on the coefficients to find the enthalpy change of the last equation.

$\Delta H _{(4)} = -\frac{1}{2} \; \Delta H _{(1)} + \frac{1}{2} \; \Delta H _{(2)} - \frac{1}{2} \; \Delta H _{(3)}\\\phantom{\Delta H _{(4)}} = -\frac{1}{2} \times (-628.9)+ \frac{1}{2} \times (-92.2) - \frac{1}{2} \times (184.7) \\\phantom{\Delta H _{(4)}} = 176.0 \; \text{kJ} \cdot \text{mol}^{-1}$

3 0

3 years ago

The idea that the earth is divided into a number of small plates that float on the mantle and slide,collide,and slip past each o

IgorLugansk [536]

Answer:

Theories

Explanation:

It is theories because it was a generalistee abstract or thinking generalising the principle of fact about Earth tectonic plates ,it was formulated and concluded as plate tectonic theories after many findings. The theories conclude that the Earth has an outer layer called lithosphere and lies overly a plastic layer called asthenosphere. The lithosphere is divided into several plates and they move close to each other where they diverge, converge or slip over one another.

7 0

3 years ago

Identify the blocks and groups of elements in the periodic table

djyliett [7]

Explanation:

The periodic table is a table that arranges elements based on their atomic numbers into groups and periods.

The groups are the vertical arrangement of elements. All elements in a group share similar chemical properties because they have the same number of elements in their valence shell. The periodic table groups are:

Group Other names

1A or 1 Alkali metals

IIA or 2 Alkaline earth metals

IIIA or 3 Boron family

VIA or 6 Chalcogens

VIIA or 17 Halogens

O-18 Inert elements

IIIB-IIB Transition elements

There are 18 vertical columns divided into 8 tall groups or main groups which are 1A to O. The short groups or subgroups are from numerals 1B to VIII.

The periodic table can be divided into four blocks based on the type of sublevels their valence electrons occupy.

Group IA and IIA constitute the s-block
Group IIIA to O constitute the p-block
The transition elements makes up the d-block
The lanthanides and actinides makes up the f-block

Learn more:

Periodic table brainly.com/question/2014634

#learnwithBrainly

3 0

3 years ago

1.Which of the following compounds give acidic solution with water:

m_a_m_a [10]

Answer:

3

Explanation:

metallic oxides are basic in nature.

7 0

3 years ago

the elements in group 2 have similar chemical properties because each atom of these elements has the same

Vsevolod [243]

They have same electronic configuration

3 0

3 years ago