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Naya [18.7K]
3 years ago
13

In the following overall chemical reaction, aluminum displaces chromium from chromium(III) oxide and forms aluminum oxide.

Chemistry
1 answer:
mafiozo [28]3 years ago
6 0

Answer:

Change in enthalpy for the reaction is -536 kJ

Explanation:

  • Overall chemical reaction can be represented a summation of two given elementary steps with slight modification.
  • Take reaction (1a) and divide stoichiometric coefficients by 2
  • Take reverse reaction (2a) and divide stoichiometric coefficient by 2
  • Then add these two modified elementary steps to get overall chemical reaction
  • \Delta H is an additive property. hence value of \Delta H will be changed in accordance with modification

2Al+\frac{3}{2}O_{2}\rightarrow Al_{2}O_{3}.....\Delta H_{1}=\frac{-3351.4}{2}kJ=-1675.7kJ

Cr_{2}O_{3}\rightarrow 2Cr+\frac{3}{2}O_{2}....\Delta H_{2}=\frac{2279.4}{2}kJ=1139.7kJ

--------------------------------------------------------------------------------------------------------------

2Al+Cr_{2}O_{3}\rightarrow 2Cr+Al_{2}O_{3}....\Delta H=\Delta H_{1}+\Delta H_{2}=-1675.7+1139.7kJ=-536kJ

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What is the frequency of light that has an energy of 1.8 x 10-15 J? 6.626 x 10-34 Js 2.7 x 1018 Hz 3.7 x 10-19 Hz 1.2 x 10-48 Hz
Ann [662]
In order to determine the frequency, we may use Planck's equation:

Energy = Planck's constant * frequency

Rearranging and substituting the values,

frequency = (1.8 x 10⁻¹⁵) / (6.63 x 10⁻³⁴)
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3 years ago
Consider the reaction H2(g) + I2(g) Double headed arrow. HI(g) with an equilibrium constant of 46.3 and a reaction quotient of 5
Alika [10]

Answer:

The reaction shifts to the left.

Explanation:

Equilibrium constant (K) = 46.3

Reaction Quotient (Q) = 525

The relationship between Q and K with their implications are given as;

K = Q (No net reaction)

K > Q (Reaction shifts to the right)

K < Q (Reaction shifts to the left)

Since in this question, Q (525) > K (46.3)

The reaction shifts to the left.

5 0
2 years ago
Magnesium reacts with hydrochloric acid to produce magnesium chloride and hydrogen gas. Write a balanced chemical equation for t
Alona [7]

Answer:

The balanced chemical equation is Mg + 2HCl ⇒ MgCl2 + H2

The molarity of the hydrochloric acid solution is HCl 0.04 M and the pH = 1.4.

The volume of hydrogen gas produced by the reaction of 0.510 g of Mg will be 0.482 L.

Explanation:

First, for the balanced equation you have to consider the oxidation state of the elements to find subscripts. Then you can find the correct coeficients. Mg= +2, Cl = -1.

Mg + HCL ⇒ MgCl2 + H2

For the molarity of the solution you have to notice tha if 0.510 grams of Mg reacts with 0,5 L of hydroclhoric acid, and from the previous equation 1 mol of Mg reacts with 2 mol HCl.

The atomic mass of Mg = 24.31 grs/mol

24.31 grs------------ 1 mol Mg

0.510 grs------------ x=0.02 mol Mg.

If 1 mol of Mg reacts with 2 mol HCl, then 0.02 mol of Mg will react with

0.04 mol HCl. So, the molarity of the solution is 0.04 M HCl.

Then to calculate the pH we use the formula pH = - log [H+]

⇒ pH = -log [0.04]⇒ pH=1.4.

Finally, from the balanced equation and the findings described, and considering that at 25°C and 1.00 atm 1 mol of gas has volume of 24.1 L.

1 mol H2----------- 24.1 L

0.02 mol H2----- x= 0.482L.

3 0
3 years ago
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