What will Number 17 be?

For a particular isomer of C 8 H 18 , the combustion reaction produces 5113.3 kJ of heat per mole of C 8 H 18 ( g ) consumed, un

ale4655 [162]

Answer:

ΔH°f(C₈H₁₈(g)) = -210.9 kJ/mol

Explanation:

Let's consider the combustion of C₈H₁₈.

C₈H₁₈(g) + 25/2 O₂(g) ⟶ 8 CO₂(g) + 9 H₂O(g) ΔH°rxn = − 5113.3 kJ

We can calculate the standard enthalpy of formation of C₈H₁₈(g) using the following expression.

ΔH°rxn = 8 mol × ΔH°f(CO₂(g)) + 9 mol × ΔH°f(H₂O(g)) - 1 mol × ΔH°f(C₈H₁₈(g)) - 25/2 mol × ΔH°f(O₂(g))

1 mol × ΔH°f(C₈H₁₈(g)) = 8 mol × ΔH°f(CO₂(g)) + 9 mol × ΔH°f(H₂O(g)) - 25/2 mol × ΔH°f(O₂(g)) - ΔH°rxn

1 mol × ΔH°f(C₈H₁₈(g)) = 8 mol × (-393.5 kJ/mol) + 9 mol × (-241.8 kJ/mol) - 25/2 mol × 0 kJ/mol - (− 5113.3 kJ)

ΔH°f(C₈H₁₈(g)) = -210.9 kJ/mol

5 0

3 years ago

Read the given equation. 2Na + 2H2O ? 2NaOH + H2 During a laboratory experiment, a certain quantity of sodium metal reacted with

emmasim [6.3K]

Answer:

The number of moles of Na metal that used initially = 0.70 mol.

The quantity of Na metal used initially to produce 7.80 of H₂ gas = 16.02 g.

Explanation:

It is a stichiometry problem.

2Na + 2H₂O → 2NaOH + H₂,

The balanced equation shows that 2.0 moles of Na metal react with 2.0 moles of water to produce 2.0 moles of NaOH and 1.0 mole of H₂,

Firstly, we need to convert the volume of H₂ (7.80 L) produced to no. of moles (n) using the ideal gas law: PV = nRT,

where, P is the pressure of the gas in atm (P at STP = 1.0 atm),

V is the volume of the gas in L (V = 7.80 L),

n is the number of moles in mole,

R is the general gas constant (R = 0.082 L.atm/mol),

T is the temperature of the gas in K (T at STP = 0.0 °C + 273 = 273.0 K).

∴ The number of moles of H₂ gas (n) = PV / RT = [(1.0 atm)(7.80 L)] / [(0.082 L.atm/mol.K)(273.0 K)] = 0.35 mol.

Using cross multiplication:

2.0 moles of Na will produce → 1.0 mole of H₂, from the stichiometrey.

??? moles of Na will produce → 0.35 mole of H₂.

∴ The number of moles of Na metal that used initially = (2.0 mol)(0.35 mol) / (1.0 mol) = 0.70 mol.

Now, we can get the quantity of Na metal using the relation:

∴ mass = n x molar mass = (0.70 mol)(22.989 g/mol) = 16.02 g.

6 0

3 years ago

in the modern wave-mechanical model of the atom, the orbitals are regions of the most probable location of

irina [24]

The orbital is the probable location of the electron of an atom.

Always remember the difference between Bohr and wave-mechanical model in terms of electrons!

Your questions answer is Electron!

But you should also know Bohr said electrons are in orbitals in a fixed proportion, but modern wave mechanical disagrees with this and said electrons are arranged in a very complex random proportion in a region called orbital!

Hope this helped

have a smiley day (:

5 0

3 years ago

True or False? Chemical manufacturers strive to produce herbicides

julsineya [31]

Answer:

True.

Explanation:

Chemical manufacturers strive to produce herbicides and insecticides that get rid of all pests, beneficial or not because pests and weeds reduces both quality and quantity of the crops which directly affects country's economic conditions. There are several countries which are agricultural based means they depend on the agricultural goods. So for producing maximum yield of crops, they use pesticides and herbicide to make the crop free from the pest and weeds. So chemical manufacturers produce chemicals for pest and weeds.

3 0

3 years ago

In a chemical reaction, substrate molecule A is broken down to form one molecule of product B and one molecule of product C. The

MAVERICK [17]

Answer:

The answer to your question is d. 0.5 M

Explanation:

Data

[A] = 1M

K = 0.5

Concentration of B and C at equilibrium = x

Concentration of A at equilibrium = 1 - x

Equation of equilibrium

k = $\frac{[B][C]}{A}$

Substitution

$0.5 = \frac{[x][x]}{1 - x}$

Simplification

0.5 = $\frac{x^{2}}{1 - x}$

Solve for x

0.5(1 - x) = x²

0.5 - 0.5x = x²

x² + 0.5x - 0.5 = 0

Find the roots x₁ = 0.5 x₂ = -1

There are no negative concentrations so the concentration of A at equilibrium is

[A] = 1 - 0.5

= 0.5 M

4 0

3 years ago