The parent element 42 19 K decays by beta decay. Which daughter element will

Chemistry

1 answer:

wel2 years ago

8 0

Answer: A

Explanation:

This means that the atomic number decreases by 1 but the mass remains constant, meaning the atomic number of the new element is 20. This corresponds to calcium.

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Which energy transfer takes place when water freezes to form ice crystals in the atmosphere?

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<span>Energy is transferred from the water into the air </span>

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4 years ago

For a chemical reaction to be spontaneous only at high temperatures, which conditions must be met?

Oksana_A [137]

According to the Gibbs Free Energy equation, some reactions only occur spontaneously at very high temperatures. At high temperatures, the reaction becomes spontaneous if both the entropy as well as the enthalpy are positive.

Changes in Enthalpy, Entropy, as well as Free Energy, Remember that such temperature in the Gibbs free energy equation would be the Kelvin temperature, and as such, it can only be positive. The reaction will constantly be spontaneous at any and all temperatures when H is negative and S is positive, and G's sign is going to be negative.

If a reaction happens without any outside influence, it has been said to as spontaneous. This reaction can release energy and only takes place in the specific circumstances.

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2 years ago

One kilogram of water at 100 0C is cooled reversibly to 15 0C. Compute the change in entropy. Specific heat of water is 4190 J/K

mina [271]

Answer:

The change in entropy is -1083.112 joules per kilogram-Kelvin.

Explanation:

If the water is cooled reversibly with no phase changes, then there is no entropy generation during the entire process. By the Second Law of Thermodynamics, we represent the change of entropy ( $s_{2} - s_{1}$ ), in joules per gram-Kelvin, by the following model:

$s_{2} - s_{1} = \int\limits^{T_{2}}_{T_{1}} {\frac{dQ}{T} }$

$s_{2} - s_{1} = m\cdot c_{w} \cdot \int\limits^{T_{2}}_{T_{1}} {\frac{dT}{T} }$

$s_{2} - s_{1} = m\cdot c_{w} \cdot \ln \frac{T_{2}}{T_{1}}$ (1)

Where:

$m$ - Mass, in kilograms.

$c_{w}$ - Specific heat of water, in joules per kilogram-Kelvin.

$T_{1}$ , $T_{2}$ - Initial and final temperatures of water, in Kelvin.

If we know that $m = 1\,kg$ , $c_{w} = 4190\,\frac{J}{kg\cdot K}$ , $T_{1} = 373.15\,K$ and $T_{2} = 288.15\,K$ , then the change in entropy for the entire process is: