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Marrrta [24]
3 years ago
5

A 4.000 g sample of iron was heated from 0.0°C to 21.0°C. If it has a specific heat of 0.440 kJ/kg °C, how many kilojoules of he

at does it absorb?
Chemistry
1 answer:
Mashutka [201]3 years ago
6 0
M = 4 g = 4/1000 kg = 0.004 kg, θ₂ = 21.0°C, θ₁ = 0°C , c = 0.44kJ/kg°C,

Q = mc(θ₂ - θ₁)

Q = 0.004*0.440*(21 - 0)

Q  =  0.03696 kJ 

0.03696 kJ<span> of heat is absorbed.</span>
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Consider the following reaction where Kc = 1.80×10-2 at 698 K:
Klio2033 [76]

Answer:

The system is not in equilibrium and the reaction must run in the forward direction to reach equilibrium.

Explanation:

The reaction quotient Qc is a measure of the relative amount of products and reagents present in a reaction at any given time, which is calculated in a reaction that may not yet have reached equilibrium.

For the reversible reaction aA + bB⇔ cC + dD, where a, b, c and d are the stoichiometric coefficients of the balanced equation, Qc is calculated by:

Qc=\frac{[C]^{c}*[D]^{d}  } {[A]^{a}*[B]^{b}}

In this case:

Qc=\frac{[H_{2} ]*[I_{2} ] } {[HI]^{2}}

Since molarity is the concentration of a solution expressed in the number of moles dissolved per liter of solution, you have:

  • [H_{2} ]=\frac{2.09*10^{-2} moles}{1 Liter}=2.09*10⁻² \frac{moles}{liter}
  • [I_{2} ]=\frac{4.14*10^{-2} moles}{1 Liter}=4.14*10⁻² \frac{moles}{liter}
  • [I_{2} ]=\frac{0.280 moles}{1 Liter}= 0.280 \frac{moles}{liter}

So,

Qc=\frac{2.09*10^{-2} *4.14*10^{-2}  } {0.280^{2} }

Qc= 0.011

Comparing Qc with Kc allows to find out the status and evolution of the system:

If the reaction quotient is equal to the equilibrium constant, Qc = Kc, the system has reached chemical equilibrium.

If the reaction quotient is greater than the equilibrium constant, Qc> Kc, the system is not in equilibrium. In this case the direct reaction predominates and there will be more product present than what is obtained at equilibrium. Therefore, this product is used to promote the reverse reaction and reach equilibrium. The system will then evolve to the left to increase the reagent concentration.

If the reaction quotient is less than the equilibrium constant, Qc <Kc, the system is not in equilibrium. The concentration of the reagents is higher than it would be at equilibrium, so the direct reaction predominates. Thus, the system will evolve to the right to increase the concentration of products.

Being Qc=0.011 and Kc=1.80⁻²=0.018, then Qc<Kc. <u><em>The system is not in equilibrium and the reaction must run in the forward direction to reach equilibrium.</em></u>

8 0
3 years ago
Which of the following describes the tiny particles that make up matter?
Ksenya-84 [330]
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3 years ago
Which statement describes a system that consists of sugar crystals dissolving in water?
trapecia [35]

To know the answer, you either know what is really the nature and chemistry of a sugar solution. You can also know the answer by knowing the meaning of entropy. Entropy is often interpreted as the degree of disorder or randomness in the system. So the correct statement is that the system becomes more disordered and has an increase in entropy.

7 0
3 years ago
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Consider the following reaction at 298K.
lakkis [162]

The true statements are;

  • K < 0
  • Eocel  < 0

<h3>What is a redox reaction?</h3>

We define a redox reaction as one in which a specie is oxidized and another is reduced.

Now;

Eo cell = cell potential = -0.13 V - (+0.34 V) = -0.47 V

n =number of moles of electrons = 2 mole of electrons

K = equilibrium constant

ΔG = change in free energy

Eo cell = 0.0592/n log K

-0.47 =  0.0592/2 log K

log K =  -0.47  * 2/0.0592

K = 1.3 * 10^-16

ΔG = -nFEo cell

ΔG = -(2 * 96500 * -0.47)

ΔG = 90.7kJ

Learn more about Ecell:brainly.com/question/10203847

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8 0
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When was the death of all dinosuars?
liberstina [14]
The Cretaceous-Tertiary extinction event , the name given to the die off dinosaurs, they all died off about 65.5 million years ago . They died by climate and geological changes .
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