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Soloha48 [4]
3 years ago
15

Chemistry questions below! (●'◡'●)

Chemistry
1 answer:
bearhunter [10]3 years ago
4 0

(1) Islands are always surrounded by bodies of water, in this case oceans. These islands tend to have more 'stable climates' and 'smaller temperature fluctuations' due to the specific heat of water, which is quite high, 4180 J/kg C. The higher the specific heat, the more the energy needed to raise the temperature of the substance. Land requires less energy to raise it's temperature than water due to it's lower specific heat. Thus, islands tend to have more stable temperatures than regions surrounded by land.

(2) Based on the conditions provided, the thermochemical equation for the reaction should be:  

<u>2NaHCO₃ (s) ---> Na₂CO₃ (s) + H₂O (g) + O₂ (g)</u>

This is a decomposition reaction, as it explains that the baking soda breaks down into the products. All we had left to do is balance the equation, adding 2 as the coefficient of the reactant.

(3) Let's rewrite the given equations:

First chemical reaction: H₂(g) + F₂(g)  ---> 2HF(g), ΔH₁ = –537 kJ.

Second chemical reaction: C(s) + 2F₂(g) ---> CF₄(g), ΔH₂ = –680 kJ

Third chemical reaction: 2C(s) + 2H₂(g) ---> C₂H₄(g), ΔH₃ = +52.3 kJ.

Fourth chemical reaction: C₂H₄(g) + 6F₂(g) ---> 2CF₄(g) + 4HF(g), ΔH₄ = ?

Now the 'fourth chemical reaction' is the one in which we need to determine the enthalpy:

ΔH₄ = 2(ΔH₁) + 2(ΔH₂) - ΔH₃,

ΔH₄ = 2(–537) + 2(–680) - 52.3 =<u> -2486.3 kJ</u>

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Margarita [4]

They are mostly made of gas
They have rings
They have thick atmospheres
I hope this helps.
7 0
3 years ago
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Which element has exactly five electrons in the highest principal energy level (the outer shell)?
kap26 [50]
Boron (B) has 3 electrons in the outer shell.
Barium (Ba) has 2 electrons.
Phosphorus (P) has 5 electrons.
Manganese (Mn) has 2 electrons.

The answer is C) P (phosphorus).
4 0
3 years ago
What mass of Al would be obtained from the complete reduction of 10.2 tonnes of Al2O3?
Fynjy0 [20]

Answer:

5.4 tonnes.

Explanation:

The first step is to find the molar mass of Al2O3. Aluminum has a molar mass of about 27 and oxygen has a molar mass of about 16, so 2(27)+3(16)= 102g/mol=0.102kg/mol. 10200kg/0.102kg/mol=100,000 moles of Al2O3 in 10.2 tonnes. Multiplying this by the molar mass of the two aluminums, you get a total of 54*100,000=5400000g=5400kg=5.4 tonnes. Hope this helps!

3 0
3 years ago
Calculate the molarity when 135 g of KCl is dissolved to make a 2.50 L solution. Round to two significant digits.
inysia [295]
<h2>0.72 mol/L</h2>

Explanation:

       \textrm{Molarity of a solution}=\frac{\textrm{Number of moles of solvent}}{\textrm{Volume of solution in Liters}}

       We are given a 2.50L solution which contains 135g of KCl.

       To calculate number of moles of KCl present, we need to find it's molar mass from charts. Molar Mass of KCl is known to be 74.55\frac{g}{Mol}.

       Number of moles of KCl present = \frac{\textrm{Given weight}}{\textrm{Molar Mass}}\textrm{ = }\frac{135g}{74.55\frac{g}{Mol}}\textrm{ = }1.81087mol

       Molarity = \frac{1.81087mol}{2.50L}=0.7243\frac{mol}{L}

∴ Molarity of given KCl solution = 0.72\frac{mol}{L}

7 0
3 years ago
A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper; the aluminum and the copper are in
Illusion [34]

Answer:

  • <u>Copper</u><em> is the object that experiences the greater temperature change.</em>

Explanation:

<em>Thermally isolated system </em>means that the system does not exchange thermal energy with the surroundings.

Hence, any thermal exchange, in virtue of the temperature difference of the aluminum and copper pieces, is between them.

In consequence, the law of conservation of energy states that the heat lost by the hot substance will be gained by the cold matter.

In equations, that is:

  • Heat lost by aluminum = heat gained by copper.

Now, the gain or loss or heat of a substance, Q, is related with the mass (m), the specific heat (Cs), and the cahnge of temperature (ΔT), per the equation:

  • Q = m × Cs × ΔT

∴ Q lost by aluminum = Q  gained copper ⇒

  • [m × Cs × ΔT ] aluminum = [m × Cs × ΔT ] copper.

Under the reasoning assumption that the masses of aluminum and copper are equal, the equations is simplified to:

  • [Cs × ΔT ] aluminum = [Cs × ΔT ] copper.

  • Cs aluminum / Cs copper = ΔT copper / ΔT aluminum

  • Cs aluminum > 2 × Cs copper  ⇒ Cs

  • Cs aluminum / Cs copper > 2 ΔT copper / ΔT aluminum

  • ΔT copper / ΔT aluminum > 2

  • ΔT copper > 2 × ΔT aluminum

In words, since it is stated that  the specific heat of aluminum is more than double that of copper,  in order to keep the equality, ΔT of copper shall be more than double ΔT of aluminum.

Hence, the <u>conclusion</u> is that the object that experiences the greater temperature change is copper (the one with the lower specific heat), under the assumption that both objects have the same amount of matter (mass).

6 0
3 years ago
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