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3 years ago

Is the following a properly written thermochemical equation? 2C8H18 + 25O2 → 16CO2 + 18H2O, ΔH = –5,471 kJ/mol

1 answer:

8 0

I believe the the equation is correctly expressed. The reaction above is a combustion reaction of octane. All of the combustion reaction is known to be exothermic reactions that is they release heat as the reaction proceeds. Consequently, they have negative enthalpies.

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Cryolite (Na3AlF6) is used in the production of aluminum from its ores. It is made by the reaction 6 NaOH 1 Al2O3 1 12 HF 8n 2 N

kap26 [50]

Answer: The mass of cryolite produced in the reaction is 1181.8 g

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of aluminium oxide = 287 g

Molar mass of aluminium oxide = 102 g/mol

Putting values in equation 1, we get:

$\text{Moles of aluminium oxide}=\frac{287g}{102g/mol}=2.814mol$

The given chemical reaction follows:

$6NaOH+Al_2O_3+12HF\rightarrow 2Na_3AlF_6+9H_2O$

By Stoichiometry of the reaction:

1 mole of aluminium oxide produces 2 moles of cryolite

So, 2.814 moles of aluminium oxide will produce = $\frac{2}{1}\times 2.814=5.628mol$ of cryolite

Now, calculating the mass of cryolite by using equation 1:

Moles of cryolite = 5.628 moles

Molar mass of cryolite = 210 g/mol

Putting values in equation 1, we get:

$5.628mol=\frac{\text{Mass of cryolite}}{210g/mol}\\\\\text{Mass of cryolite}=(5.628mol\times 210g/mol)=1181.8g$

Hence, the mass of cryolite produced in the reaction is 1181.8 g

5 0

3 years ago

Which particle has the least mass?(1) alpha (3) neutron (2) beta particle (4) proton

ivann1987 [24]

Alpha particle has a mass of 4 (Two protons and two neutrons)
Neutron has a mass of 1
Beta particle has a mass of about 0 (Electron)
Proton has a mass of 1
So the answer is (2) Beta particle

4 0

3 years ago

A gas occupies a volume of 202 ml at a pressure of 505 torr. To what pressure must the gas be subject in order to change the vol

UNO [17]

Answer:

1569 torr

Explanation:

Assuming ideal behaviour and constant temperature, we can solve this problem by using Boyle's law, which states:

V₁P₁ = V₂P₂

Where in this case:

V₁ = 202 mL

P₁ = 505 torr

V₂ = 65.0 mL

P₂ = ?

We input the data given by the problem:

202 mL * 505 torr = 65.0 mL * P₂

And solve for P₂:

P₂ = 1569 torr

6 0

3 years ago

Using full detail, describe the theory of plate tectonics.

yuradex [85]

Plate tectonics is a scientific theory that describes the large-scale motion of Earth's lithosphere. Plates at our planet’s surface move because of the intense heat in the Earth’s core that causes molten rock in the mantle layer to move.

Here's a link if you need more help: http://www.livescience.com/37706-what-is-plate-tectonics.html

3 0

3 years ago

What is the connection between Oobleck and the mantle?

lapo4ka [179]

Answer:

Oobleck is a mixture of cornstarch & water, a substance that behaves like the Mantle.

Explanation:

3 0

3 years ago