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nikklg [1K]
3 years ago
10

I need help with Hess law

Chemistry
1 answer:
ICE Princess25 [194]3 years ago
6 0

Answer:

alright

Explanation:

Hess law is  the enthalpy change for a reaction that is carried out in a series of steps is equal to the sum of the enthalpy changes for the individual steps. Consistent with the law of conservation of energy. Starting and final conditions must be the same.

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shepuryov [24]

Answer:

Explanation:

All three lighter boron trihalides, BX3 (X = F, Cl, Br), form stable adducts with common Lewis bases. Their relative Lewis acidities can be evaluated in terms of the relative exothermicities of the adduct-forming reaction. Such measurements have revealed the following sequence for the Lewis acidity: BF3 < BCl3 < BBr3 (in other words, BBr3 is the strongest Lewis acid).

This trend is commonly attributed to the degree of π-bonding in the planar boron trihalide that would be lost upon pyramidalization (the conversion of the trigonal planar geometry to a tetrahedral one) of the BX3 molecule, which follows this trend: BF3 > BCl3 > BBr3 (that is, BBr3 is the most easily pyramidalized). The criteria for evaluating the relative strength of π-bonding are not clear, however. One suggestion is that the F atom is small compared to the larger Cl and Br atoms, and the lone pair electron in the 2pzorbital of F is readily and easily donated, and overlaps with the empty 2pz orbital of boron. As a result, the [latex]\pi[/latex] donation of F is greater than that of Cl or Br. In an alternative explanation, the low Lewis acidity for BF3 is attributed to the relative weakness of the bond in the adducts F3B-L.

3 0
3 years ago
Read 2 more answers
Describe the physical properties of each state of matter
Leni [432]
Solid - made up of tightly packed particles, which gives it a solid shape.
Gas - made up of very loose particles, giving it more freedom to roam around as a gas
Liquid - fills into whatever it gets put in, basically takes the shape of the object its in
6 0
3 years ago
Study the graph in Figure 6.32 and answer to these questions. (see attached image)
Dimas [21]

Hey there :)

We can see that the solubility of salt increases with increasing temperature. This happens with most substances.

To find out the maximum mass of copper sulfate that can be dissolved in water at these temperatures, just interpret the graph.

Considering Y-axis as g copper sulfate/100 g water and the X-axis as the temperature in °C:-

<u>1)</u>

a: <u>0 °C - 14 g of copper sulfate/100 g of water</u>

b: <u>50 °C - 34 g of copper sulfate/100 g of water</u>

c: <u>90 °C - 66 g of copper sulfate/100 g of </u><u>water</u>

<u>2)</u> From the graph, we can infer that temperature affects the solubility of the salt.

<em>Answered</em><em> </em><em>by</em><em> </em><em>Benjemin360</em><em> </em>:)

3 0
2 years ago
What kind of energy is stored in bonds of molecules
Ne4ueva [31]
The answer to your question would more than likely be chemical energy, natural gas, and chemical energy. but I don't know what grade your in I'm in eighth if your below I know the answer. I'm pretty sure I had a question exactly like this last year but that was last year so if it's wrong sorry. I looked it up on Google to make sure
3 0
3 years ago
Calculate the percent ionic, the percent covalent, and the bond length (in picometers) of a chemical bond between phosphorus and
kirza4 [7]

Answer:

The correct option is;

4 percent ionic, 96 percent covalent, 222 pm

Explanation:

The parameters given are;

Phosphorus:

Atomic radius = 109 pm

Covalent radius = 106 pm

Ionic radius = 212 pm

Electronegativity of phosphorus = 2.19  

Selenium:

Atomic radius = 122 pm

Covalent radius = 116 pm

Ionic radius = 198 pm

Electronegativity of selenium= 2.55  

The percentage ionic character of the chemical bond between phosphorus and selenium is given by the relation;

Using Pauling's alternative electronegativity difference method, we have;

\% \, Ionic \ Character = \left [18\times (\bigtriangleup E.N.)^{1.4}  \right ] \%

Where:

Δ E.N. = Change in electronegativity = 2.55 - 2.19 = 0.36

Therefore;

\% \, Ionic \ Character = \left [18\times (0.36)^{1.4}  \right ] \% = 4.3 \%

Hence the percentage ionic character = 4.3% ≈ 4%

the percentage covalent character = (100 - 4.3)% = 95.7% ≈ 96%

The bond length for the covalent bond is found adding the covalent radii of both atoms as follows;

The bond length for the covalent bond = 106 pm + 116 pm = 222 pm.

The correct option is therefore, 4 percent ionic, 96 percent covalent, 222 pm.

4 0
4 years ago
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