A + B-2C, ΔΗ1 1/2A + 1/5B+ C, ΔΗ» =?

Free-energy change, ΔG∘, is related to cell potential, E∘, by the equationΔG∘=−nFE∘where n is the number of moles of electrons t

mart [117]

Answer:

a) $\Delta G=372490 J$

b) $\Delta G=-568614 J$

Explanation:

a) The reaction:

$Mg(s) +Fe^{2+}(aq) \longrightarrow Mg^{2+}(aq) + Fe(s)$

The free-energy expression:

$\Delta G=-n*F*E$

$E=E_{red}-E_{ox]$

The element wich is reduced is the Fe and the one that oxidates is the Mg:

$-0.44V=E_{red}-(-2.37V)=1.93V$

The electrons transfered (n) in this reaction are 2, so:

$\Delta G=-2mol*96500 C/mol * 1.93 V$

$\Delta G=-372490 J$

b) If you have values of enthalpy and enthropy you can calculate the free-energy by:

$\Delta G=\Delta H - T* \Delta S$

with T in Kelvin

$\Delta G=-675 kJ*\frac{1000J}{kJ} - 298K*-357 J/K$

$\Delta G=-568614 J$

7 0

3 years ago

What would happen to a diver who does no exhale while surfacing from a 30 m dive?

sertanlavr [38]

Their lungs would try to expand to about 4 timed the normal volume which would force air into the various body tissues. this can cause a lung expansion injury and it could case air embolism. Air embolism is when air bubbles get trapped in blood vessels. This can lead to a blockage which will could be fatal.

6 0

3 years ago

A student obtains a mixture of the chlorides of two unknown metals, X and Z. The percent by mass of X and the percent by mass of

Aleksandr-060686 [28]

Answer: The additional information that is helpful in calculating the mole percent of XCl(s) and ZCl(s) is the molar masses of Z and X

Explanation:

To calculate the mole percent of a substance, we use the equation:

$\text{Mole percent of a substance}=\frac{\text{Moles of a substance}}{\text{Total moles}}\times 100$

Mass percent means that the mass of a substance is present in 100 grams of mixture

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

We require the molar masses of Z and X to calculate the mole percent of Z and X respectively

Hence, the additional information that is helpful in calculating the mole percent of XCl(s) and ZCl(s) is the molar masses of Z and X

8 0

3 years ago

The measure of a right angle is

yawa3891 [41]

Answer:

90° is the measure, hope this helped :)

7 0

3 years ago

Give the result of the following mathematical operations to the correct number of significant figures. 5.659 * (3.496 - 2.814) =

shtirl [24]

Answer:

The result is 3.859 in which we use four significant figures.

Explanation:

We start by solving the mathematical operation :

$5.659.(3.496-2.814)=5.659(0.682)=3.859438$

The result for the operation is 3.859438 but the numbers in the operation are given with four significant figures and that is why we are going to use four significant figures to express the result

To express 3.859438 with four significant figures we use the first four digits that appear from left to right starting by the first digit that is different to zero

In this case : 3.859 will be the result with four significant figures.

We also use a rule that says : To decide if the last significant figure remains the same we look for the value of the digit at its right.

If that number is greater than or equal to 5 ⇒ we sum one to the last significant figure

For example 3.859738 = 3.860 with four significant figures because the ''7'' is greater that 5

If that number is less than 5 ⇒ the last significant figure remains the same

In our case : 3.859438 = 3.859 because ''4'' is less than ''5''

7 0

3 years ago