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olga_2 [115]
3 years ago
5

How can models demonstrate theories of our expanding universe?​

Chemistry
1 answer:
Scilla [17]3 years ago
7 0

Answer:

Explanation:Puesto que la energía causante de la aceleración del espacio-tiempo no ha podido ser observada en forma directa, se ha dado en llamarla energía oscura. Dos candidatos teóricos que podrían hacer las veces de esta energía son una constante cosmológica no igual a cero (que pudo haber causado la inflación cósmica) y una energía repulsiva más general llamada quintaesencia.

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Help me please guys :)
nika2105 [10]

Explanation:

1. Methane

2. Diamond

3. not sure : )

6 0
3 years ago
How do the properties of elements change as you move across a period
denpristay [2]
The number of shells increase, the energy level their outer shell have decreases as we go down wards,
3 0
3 years ago
If a solution of HF (Ka=6.8×10−4) has a pH of 2.90, calculate the concentration of hydrofluoric acid.
fgiga [73]

Answer: 0.0023

Explanation:

I just answered this very same question. You can read my answer here: brainly.com/question/12077289.

1) First, you must write the balanced equilibrium equation, which will let you to determine the mole ratios of the different species in solution:

    HF ⇆ H⁺ + F⁻

Therefore, the mole ratio is: 1 HF: 1 H⁺ : 1  F⁻

2) Second, write the equilibrium constant of the acid, Ka, which will permit you to state the relationship of the concentrations in equilibrium:

        Ka = [H⁺] [F⁻] / [HF]

   [HF] is the searched concentration of the hydrofluoric acid

   From the mole ratio of the balanced chemical equation [H⁺] = [F⁻]

       Hence:

       Ka = [H⁺] [H⁺] / [HF] = [H⁺]² / [HF]

3) From the pH value you can calculate [H⁺],  using the definition:

  •    pH= - log [H⁺]
  •    Substitute: 2.90 = - log [H⁺]

 

 Clear [H⁺] using logarithm properties:

         [H^+]=10^{-2.90}=0.00126

4) Now you can substitute [H⁺] and the value of Ka in the equation for Ka:

   Ka = [H⁺]² / [HF] ⇒ [HF] = [H⁺]² / Ka = (0.00126)² / (6.8×10⁻⁴) = 0.00233.

Since the value of Ka has two significant figures, you must report the answer with two significan figures, i.e. 0.0023

7 0
3 years ago
The methane used to obtain H₂ for NH₃ manufacture is impure and usually contains other hydrocarbons, such as propane,C₃H₈. Imagi
quester [9]

According to the ideal gas law, partial pressure is inversely proportional to volume. It is also directly proportional to moles and temperature. At equilibrium in the following reaction at room temperature, the partial pressures of the gases are found to be PN2 = 0.094 atm, PH2 = 0.039 atm, and PNH3 = 0.003 atm.

<h3>Equilibrium partial pressures</h3>

The initial partial pressures of CO and water are 4.0 bar and 4.0 bar respectively.

The equilibrium partial pressures (in the bar) of CO, H2​O, CO2​, and H2​ are 4−p,4−p, and respectively.

Let p bar be the equilibrium partial pressure of hydrogen.

The expression for the equilibrium constant is

Kp​=PCO​PH2​O​PCO2​​PH2​​​=(4−p)(4−p)p×p​=0.1

p=1.264−0.316p

p=0.96 bar.

To learn more about equilibrium constant visit the link

brainly.com/question/10038290

#SPJ4

5 0
1 year ago
Secondary succession can only occur as a transition from primary succession.
Debora [2.8K]

Answer:

T

Explanation:

Hope this helps(Truth)

:)

6 0
3 years ago
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