Chemistry, 23.12.2019 04:31 pearlkissp1bzl8

Calculate the change in internal energy of the following system: a 100.0-g bar of gold is heated from 25 ∘c to 50 ∘c during which it absorbs 322 j of heat. assume the volume of the gold bar remains constant.

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Answer from: enrique710

The change in internal energy of a gold bar is $\boxed{{\text{322 J}}}$

Further explanation:

Thermodynamics:

It is branch of chemistry that is related to heat temperature and connection with work is known as thermodynamics it has wide uses in pyrometallurgy, gas phase reaction gas solid reaction and ATP generation and many more.

First law of Thermodynamics:

It is based on law of energy conservation that states total energy of system remains constant. According to this law, internal energy change is determined by sum of work done on the system and heat supplied. Its mathematical expression is as follows:

$\Delta {\text{U}}={\text{q}}+{\text{W}}$ …… (1)

Here,

$\Delta{\text{U}}$ is the change in internal energy of the system.

q is the heat supplied to the system.

W is the work done on the system.

The formula to calculate the work done is as follows:

${\text{W}}={\text{P}}\Delta{\text{V}}$ …… (2)

Here,

W is the work done.

P is the pressure on the system.

$\Delta{\text{V}}$ is the change in the volume of the system.

It is given that the volume of the gold bar remains constant. This implies $\Delta{\text{V}}$ to be zero.

Substitute 0 for $\Delta{\text{V}}$ in equation (2) to calculate the work done on the gold bar.

$\begin{aligned}{\text{W}}&={\text{P}}\left( 0 \right)\\&=0\\\end{aligned}$

The value of q is 322 J.

The value of W is 0.

Substitute these values in equation (1) to calculate the change in the internal energy of the gold bar.

$\begin{gathered}\Delta{\text{U}}={\text{322 J}}+0\\={\text{322 J}}\\\end{gathered}$

So the change in internal energy of gold bar is 322 J.

Learn more:

1. What is the final temperature of copper? link

2. Calculate the specific heat of gold: link

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Thermodynamics

Keywords: internal energy, heat, work, q, W, P, 322 J, 0, thermodynamics, first law of thermodynamics, law of conservation of energy, total energy, isolated system, volume, constant.

Answer from: Quest

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is $1s^{2}2s^{2}2p^{6}3s^{1}$ and electronic configuration of phosphorous is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$ .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

$3na + p \rightarrow na_{3}p$

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.