The specific heat of a given substance

why do all of these elements- hydrogen, helium, lithium, and beryllium all have negative charges? explain

Dmitry_Shevchenko [17]

They all don’t, they also can have positive charges like LiOH (Lithium Hydroxide)

3 0

3 years ago

1. For each of the molecules below, determine the electron geometry, molecule geometry, and bond

Alexxx [7]

Answer:

CCl4- tetrahedral bond angle 109°

PF3 - trigonal pyramidal bond angles less than 109°

OF2- Bent with bond angle much less than 109°

I3 - linear with bond angles = 180°

A molecule with two double bonds and no lone pairs - linear molecule with bond angle =180°

Explanation:

Valence shell electron-pair repulsion theory (VSEPR theory) helps us to predict the molecular shape, including bond angles around a central atom, of a molecule by examination of the number of bonds and lone electron pairs in its Lewis structure. The VSEPR model assumes that electron pairs in the valence shell of a central atom will adopt an arrangement which tends to minimize repulsions between these electron pairs by maximizing the distance between them. The electrons in the valence shell of a central atom are either bonding pairs of electrons, located primarily between bonded atoms, or lone pairs. The electrostatic repulsion of these electrons is reduced when the various regions of high electron density assume positions as far apart from each other as possible.

Lone pairs and multiple bonds are known to cause more repulsion than single bonds and bond pairs. Hence the presence of lone pairs or multiple bonds tend to distort the molecular geometry geometry away from that predicted on the basis of VSEPR theory. For instance CCl4 is tetrahedral with no lone pair and four regions of electron density around the central atom. This is the expected geometry. However OF2 also has four regions of electron density but has a bent structure. The molecule has four regions of electron density but two of them are lone pairs causing more repulsion. Hence the observed bond angle is less than 109°.

8 0

2 years ago

Given these reactions, where X represents a generic metal or metalloid 1 ) H 2 ( g ) + 1 2 O 2 ( g ) ⟶ H 2 O ( g ) Δ H 1 = − 241

anygoal [31]

Answer : The enthalpy of the given reaction will be, -1048.6 kJ

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

The main reaction is:

$XCl_4(s)+2H_2O(l)\rightarrow XO_2(s)+4HCl(g)$ $\Delta H=?$

The intermediate balanced chemical reactions are:

(1) $H_2(g)+\frac{1}{2}O_2(g)\rightarrow H_2O(g)$ $\Delta H_1=-241.8kJ$

(2) $X(s)+2Cl_2(g)\rightarrow XCl_4(s)$ $\Delta H_2=+461.9kJ$

(3) $\frac{1}{2}H_2(g)+\frac{1}{2}Cl_2(g)\rightarrow HCl(g)$ $\Delta H_3=-92.3kJ$

(4) $X(s)+O_2(g)\rightarrow XO_2(s)$ $\Delta H_4=-789.1kJ$

(5) $H_2O(g)\rightarrow H_2O(l)$ $\Delta H_5=-44.0kJ$

Now reversing reaction 2, multiplying reaction 3 by 4, reversing reaction 1 and multiplying by 2, reversing reaction 5 and multiplying by 2 and then adding all the equations, we get :

(1) $2H_2O(g)\rightarrow 2H_2(g)+O_2(g)$ $\Delta H_1=2\times 241.8kJ=483.6kJ$

(2) $XCl_4(s)\rightarrow X(s)+2Cl_2(g)$ $\Delta H_2=-461.9kJ$

(3) $2H_2(g)+2Cl_2(g)\rightarrow 4HCl(g)$ $\Delta H_3=4\times -92.3kJ=-369.2kJ$

(4) $X(s)+O_2(g)\rightarrow XO_2(s)$ $\Delta H_4=-789.1kJ$

(5) $2H_2O(l)\rightarrow 2H_2O(g)$ $\Delta H_5=2\times 44.0kJ=88.0kJ$

The expression for enthalpy of main reaction will be:

$\Delta H=\Delta H_1+\Delta H_2+\Delta H_3+\Delta H_4+\Delta H_5$

$\Delta H=(483.6)+(-461.9)+(-369.2)+(-789.1)+(88.0)$

$\Delta H=-1048.6kJ$

Therefore, the enthalpy of the given reaction will be, -1048.6 kJ

4 0

2 years ago

Select the correct answer. Elements Electronegativity aluminum (Al) 1.61 calcium (Ca) 1 carbon (C) 2.55 chlorine (Cl) 3.16 fluor

marishachu [46]

Answer: Fe - O

Explanation:

1) Start by showing the chart information in a more understandable way:

Elements ---------- Electronegativity

aluminum (Al) ----- 1.61

calcium (Ca) ------- 1

carbon (C) ---------- 2.55

chlorine (Cl) -------- 3.16

fluorine (F) --------- 4

hydrogen (H) ------ 2.2

iron (Fe) ------------- 1.83

nitrogen (N) --------- 3.04

oxygen (O) ----------- 3.44

phosphorus (P) ----- 2.19

potassium (K) -------- 0.82

silicon (Si) ------------- 1.9

sulfur (S) --------------- 2.58

2) Find the electronegativity differences for the atoms in each compound:

i) Ca – Cl: 3.16 - 1 = 2.16

ii) Fe – O: 3.44 - 1.83 = 1.61

iii) H – S: 2.58 - 2.2 = 0.38

iii= F – F = 4 - 4 = 0

3) Analysis

i) The higher the electronegativity difference between two non-metal elements, the the more the polar the covalent bond. Therefore, the bond H - S is the most polar among the non-metal - non-metal bonds listed. But 0.38 is a small difference, so this is not very polar.

ii) For metal - non-metal bonds, when the difference in electronegativities is too high (close to or greater than 2.0) the ionic character is dominant, and so you cannot classify the bond as polar but as ionic. Therefore, Ca - Cl with 2.16 electronegativity difference is a ionic bond.

iii) The bond in Fe – O has electronegativty difference of 1.61, so it is yet covalent, and highly polar.

Read more on Brainly.com - brainly.com/question/1309389#readmore

8 0

2 years ago

Read 2 more answers

What is in an inorganic molecule?

valentinak56 [21]

Inorganic molecules are composed of other elements. They can contain hydrogen or carbon, but if they have both, they are organic.

6 0

3 years ago