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svet-max [94.6K]

2 years ago

15

A frictionless piston-cylinder device contains a saturated liquid and water vapor mixture at 110 ℃. During a constant pressure p

rocess, 546 kJ of heat is transferred to the surrounding air at 15 ℃. As a result, the vapor part inside the cylinder condenses. Determine a) the entropy change of the water and b) the generation of total entropy during this heat transfer process.

1 answer:

Charra [1.4K]2 years ago

8 0

Explanation:

(a) It is given that heat transferred is -546 kJ (as heat is releasing) and temperature is 110 degree celsius.

Hence, the temperature in kelvin will be as follows.

(110 + 273) K

= 383 K

As it is known that relation between entropy change and heat is as follows.

S = $\frac{Q}{T}$

Putting the given values in the above equation as follows.

S = $\frac{Q}{T}$

= $\frac{546 kJ}{383 K}$

= -1.4255 kJ/K

As temperature changes from $110 ^{o}C$ to $15 ^{o}C$ . So, (15 + 273) K = 288 K. Hence, change in entropy will be calculated as follows.

$\Delta S = \frac{Q}{T}$

= $\frac{546 kJ}{288 K}$

= 1.895 kJ/K

Therefore, entropy change of water will be 1.895 kJ/K.

(b) As total entropy generated will be the sum of both the entropies as follows.

Total entropy = (-1.4255 kJ/K + 1.895 kJ/K)

= 0.4695 kJ/K

Thus, total entropy during this heat transfer process is 0.4695 kJ/K.

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A mineral sample is obtained from a region of the country that has high arsenic contamination. An elemental analysis yields the

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Answer:

<em><u>CaAsHO₄</u></em>

Explanation:

The data has a mistake in one of the values there. I believe the mistake is on the hydrogen. So, I'm going to assume the value of Hydrogen is 0.6%, so the total percent composition would be 100.1% (Something better). All you have to do is replace the correct value of H (or the value with the mistaken option) and do the same procedure.

Now, to calculate the empirical formula, we can do this in three steps.

<u>Step 1. Calculate the amount in moles of each element.</u>

In these case, we just divide the percent composition with the molar mass of each one of them:

Ca: 22.3 / 40.078 = 0.5564

As: 41.6 / 74.9216 = 0.5552

O: 35.6 / 15.9994 = 2.2251

H: 0.6 / 1.00794 = 0.5953

Now that we have done this, let's calculate the ratio of mole of each of them. This is doing dividing the smallest number of mole between each of the moles there. In this case, the moles of As are the smallest so:

Ca: 0.5564/0.5552 = 1.0022

As: 0.5552/0.5552 = 1

O: 2.2251/0.5552 = 4.0077

H: 0.5953/0.5552 = 1.0722

Now, we round those numbers, and that will give us the number of atoms of each element in the empirical formula

<u>Step 3. Write the empirical formula with the rounded numbers obtained</u>

In this case we will have:

Ca: 1

As: 1

O: 4

H: 1

The empirical formula would have to be:

<em><u>CaAsHO₄</u></em>

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2 years ago

The maximum amount of solute that dissolves in a given amount of solvent and forms a stable solution is called the

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Answer:

The maximum amount of solute that dissolves in a given amount of solvent and forms a stable solution is called the solubility of the solute

Explanation:

The maximum amount of solute that could be dissolved in a given amount of solvent is the solubility of the solute. It is the saturated solution's concentration from where a saturated solution can be defined as the one which already contains the maximum quantity of dissolved solute at a specified temperature, while an unsaturated solution is one with a capacity to dissolve more solutes

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<span>A machine is a device that does work. Most machines consist of a number of elements, such as gears and ball bearings, that work together in a complex way. Nonetheless, no matter how complex they are, all machines are based in some way on six types of simple machines. These six types of machines are the lever, the wheel and axle, the pulley, the inclined plane, the wedge, and t</span>

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3 years ago

Hich of the following statements is true about what happens during a chemical reaction?

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I believe it is <span>d. the bonds of both the reactants and the products are formed.</span>

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2 years ago

We want to calculate the concentrations of all species in a 0.58 M Na 2 SO 3 (sodium sulfite) solution. The ionization constants

NeX [460]

Explanation:

Reaction equation is as follows.

$Na_{2}SO_{3}(s) \rightarrow 2Na^{+}(aq) + SO^{2-}_{3}(aq)$

Here, 1 mole of $Na_{2}SO_{3}$ produces 2 moles of cations.

$[Na^{+}] = 2[Na_{2}SO_{3}] = 2 \times 0.58$

= 1.16 M

$[SO^{2-}_{3}] = [Na_{2}SO_{3}]$ = 0.58 M

The sulphite anion will act as a base and react with $H_{2}O$ to form $HSO^{-}_{3}$ and $OH^{-}$ .

As, $K_{b} = \frac{K_{w}}{K_{a_{2}}}$

= $\frac{10^{-14}}{6.3 \times 10^{-8}}$

= $1.59 \times 10^{-7}$

According to the ICE table for the given reaction,

$SO^{2-}_{3} + H_{2}O \rightleftharpoons HSO^{-}_{3} + OH^{-}$

Initial: 0.58 0 0

Change: -x +x +x

Equilibrium: 0.58 - x x x

So,

$K_{b} = \frac{[HSO^{-}_{3}][OH^{-}]}{[SO^{2-}_{3}]}$

$1.59 \times 10^{-7} = \frac{x^{2}}{0.58 - x}$

$x^{2} = 1.59 \times 10^{-7} \times (0.58 - x)$

x = 0.0003 M

So, x = $[HSO^{-}_{3}] = [OH^{-}]$ = 0.0003 M

$[SO^{2-}_{3}]$ = 0.58 - 0.0003

= 0.579 M

Now, we will use $[HSO^{-}_{3}]$ = 0.0003 M

The reaction will be as follows.

$HSO^{2-}_{3} + H_{2}O \rightleftharpoons H_{2}SO_{3} + OH^{-}$

Initial: 0.0003

Equilibrium: 0.0003 - x x x

$K_{b} = \frac{x^{2}}{0.0003 - x}$

$K_{b} = \frac{K_{w}}{K_{a_{1}}}$

= $\frac{10^{-14}}{1.4 \times 10^{-2}}$

= $7.14 \times 10^{-13}$

Therefore, $7.14 \times 10^{-13} = \frac{x^{2}}{0.0003 - x}$

As, x <<<< 0.0003. So, we can neglect x.

Therefore, $x^{2} = 7.14 \times 10^{-13} \times 0.0003$

= $0.00214 \times 10^{-13}$

x = $0.0146 \times 10^{-6}$

x = $[OH^{-}] = [H_{2}SO_{3}]$ = $1.46 \times 10^{-8}$

$[H^{+}] = \frac{10^{-14}}{[OH^{-}]}$

= $\frac{10^{-14}}{0.0003}$

= $3.33 \times 10^{-11}$ M

Thus, we can conclude that the concentration of spectator ion is $3.33 \times 10^{-11}$ M.

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2 years ago