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Bess [88]
2 years ago
8

Research is being carried out on cellulose as a source of chemicals for the production of fibers, coatings, and plastics. Cellul

ose consists of long chains of glucose molecules (C6H12O6), so for the purposes of modeling the reaction we can consider the conversion of glucose to formaldehyde (H2CO).
1. Calculate the heat of reaction for the conversion of 1 mole of glucose into formaldehyde, given the following thermochemical data:
H2CO(g) + O2(g) -------> CO2(g) + H2O(g) ΔH °comb = - 572.9 KJ/mol
6 C(s) + 6 H2(g) + 3 O2(g) -------> C6H12O6(s) ΔH ° f = - 1274.4 KJ/mol
C(s) + O2(g) ---------> CO2(g) ΔH ° f = - 393.5 KJ/mol
H2(g) + 1 / 2 O2(g) -----------> H2O(g) ΔH ° f = - 285.8 KJ/mol
C6H12O6(s) ---------> 6 H2CO(g) ΔH ° rxn = ?
Chemistry
1 answer:
Luden [163]2 years ago
8 0

Answer:

+ 636 KJ

Explanation:

We want to arrive to the equation

C6H12O6(s) ---------> 6 H2CO(g) ΔH ° rxn = ?

by manipulating algebraically the first four  given equations.

We notice the first one has our product H2CO(g) as a reactant. This indicates we must take the inverse of that equation. Also we need 6 mol of H2CO(g), thus it also needs to be multiplied by 6

6 CO2(g) + 6 H2O(g)  ------->6H2CO(g) + 6O2(g)  ΔH °comb = + 572.9 KJ/x 6

Now we want C6H12O6(s) as a reactant and it  is a product in the second one, therefore lets reverse it

C6H12O6(s)  -------> 6 C(s) + 6 H2(g) + 3 O2(g)   ΔH ° f = + 1274.4 KJ/mol

Now if take the third equation and multiply it by six we will cancel the C(s) with the above equation

6 C(s) + 6O2(g) ---------> 6 CO2(g) ΔH ° f = - 393.5 KJ/mol x 6

Finally by multiplying the last equation by 6 and adding all the equations we will arrive at our desired one

6 H2(g) + 3 O2(g) -----------> 6H2O(g) ΔH ° f = - 285.8 KJ/mol x 6

then lets add them to get ΔH ° rxn:

  6 CO2(g) + 6 H2O(g)  ------->6H2CO(g) + 6O2(g)  ΔH °comb = + 3437.4 KJ

+ C6H12O6(s)  -------> 6 C(s) + 6 H2(g) + 3 O2(g)      ΔH ° f = + 1274.4 KJ

+ 6C(s) + 6O2(g) ---------> 6 CO2(g)                            ΔH ° f = - 2361.0 KJ

+6 H2(g) + 3 O2(g) -----------> 6H2O(g)                      ΔHº f  = - 1714.8 KJ

<u>                                                                                                                            </u>

C6H12O6(s) ---------> 6 H2CO(g)  

ΔH ° rxn =  3437.4 + 1274.4 - 2361.0 - 1714.8 =  636 KJ

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motikmotik

Answer:

On the picture are all principles cited on wikipedia.

Explanation:

So the answer is

1. Environment must be exploited to improve living standards

2. Flourishing human and nonhuman life depends on diversity of life forms

5 0
2 years ago
How many molecules of CBr4 are in 250 grams of CBr4
Kazeer [188]

Answer:- 4.54*10^2^3 molecules.

Solution:- The grams of tetrabromomethane are given and it asks to calculate the number of molecules.

It is a two step unit conversion problem. In the first step, grams are converted to moles on dividing the grams by molar mass.

In second step, the moles are converted to molecules on multiplying by Avogadro number.

Molar mass of CBr_4  = 12+4(79.9)  = 331.6 g per mol

let's make the set up using dimensional analysis:

250g(\frac{1mol}{331.6g})(\frac{6.022*10^2^3molecules}{1mol})

= 4.54*10^2^3 molecules

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8 0
1 year ago
. Citric acid, which can be obtained from lemon juice, has the molecular formula C6H8O7. A 0.250-g sample of citric acid dissolv
marysya [2.9K]

Answer:

3 acidic hydrogens per molecule of citric acid

Explanation:

In a sample of 37.2 mL(0.0372 L) of 0.105 mol/L of NaOH, will have:

n = 0.105x0.0372 = 0.0039 mol of NaOH

The dissociation of NaOH will give the same number of moles of Na⁺ and OH⁻.

The molar mass of citric acid is:

C: 12g/mol x 6 = 72 g/mol

H: 1g/mol x 8 = 8g/mol

O: 16 g/mol x 7 = 112 g/mol

192 g/mol

So, 0.250g of the acid has

n = mass/molar mass

n = 0.250/192

n = 0.0013 mol.

To be neutralized, it will be necessary 0.0039 mol of acidic hydrogens to react with the 0.0039 mol of OH⁻.

The dissociation reaction of one molecule of  the acid will give the stoichiometry:

1 mol of acid ----------------------- x mol of acidic hydrogens

0.0013 mol --------------------------- 0.0039

For a simple direct three rule:

0.0013x = 0.0039

x = 3 acidic hydrogens per molecule of citric acid.

3 0
2 years ago
Exactly 56 grams of iron is mixed with 156 grams of oxygen. The elements are heated and they react. What best describes which re
Mars2501 [29]

Answer:

Explanation:

The chemical expression for the reaction between iron and oxygen is:

4Fe(s)  +  3O₂ (g)  \to 2Fe₂O₃ (s)

The number of moles of Fe = mass of Fe/ molecular mass of Fe

The number of moles of Fe = 56 g/ 55.845 g/mol

The number of moles of Fe = 1.002 moles of Fe

The number of moles of oxygen = mass of oxygen/ molecular mass of oxygen

The number of moles of oxygen = 156 g /32 g/mol

The number of moles of oxygen = 4.875 moles of oxygen

Assume that Fe is the limiting reactant, the number of Fe₂O₃ can be calculated as:

moles of Fe₂O₃ = 1.002 mole of Fe × 2 moles of Fe₂O₃/ 4 moles of Fe

moles of Fe₂O₃ = 0.501 mole of Fe₂O₃

Assume that O₂ is the limiting factor, the number of Fe₂O₃ is:

moles of Fe₂O₃ = 4.875 moles of O₂ × 2 moles of Fe₂O₃/ 3 moles of O₂

moles of Fe₂O₃ = 3.25 mole of Fe₂O₃

Thus, after the reaction is complete, Fe and O₂ contain different moles of Fe₂O₃. Only Fe gets consumed in the reaction and it is the limiting factor.

8 0
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4 The less electronegative atoms transfers one or more electrons to the more electronegative atom.

5 The metal atom forms a cation and the nonmetal atom forms an anion.

7 The attraction between ions with an opposite charge forms an ionic bond.



8 0
2 years ago
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