Acetylsalicylic acid (hc9h7o4) is a weak acid that dissociates in water in the following manner. hc9h7o4(aq) + h2o(l) equilibrium reaction arrow c9h7o4−(aq) + h3o+(aq) at a temperature of 298.15 k, the acid-dissociation constant (ka) for acetylsalicylic acid is 3.3 ✕ 10−4. (a) calculate the change in standard free energy (δg°) for this equilibrium reaction. kj/mol (b) what is the value of δg at equilibrium? δg > 0 δg = 0 δg < 0 (c) if the reaction were spontaneous in the forward direction, what type of value would you expect for δg?

(a) -20 kJ/mol

(b) ΔG = 0

(c) A negative value

Explanation:

(a) Calculate the change in standard free energy (ΔG°) for this equilibrium reaction.

We can calculate the standard Gibbs free energy using the following expression:

ΔG° = R.T. lnKc

where,

R is the ideal gas constant

T is the absolute temperature

Kc is the equilibrium constant (in this case Kc = Ka because the reaction is an acid dissociation)

If we replace this expression with the given values, then:

ΔG° = R.T. lnKc

ΔG° =

(b) What is the value of ΔG at equilibrium?

Let us consider a more general expression for equilibrium and non-equilibrium situations:

ΔG = ΔG° + R.T. lnQ

where,

ΔG is Gibbs free energy in that situation

Q is the reaction quotient

At equilibrium, ΔG = 0, Q = Kc, and we get the first expression.

(c) If the reaction were spontaneous in the forward direction, what type of value would you expect for ΔG?

A negative ΔG implies that the forward reaction is spontaneous.

pla·gia·rism

/ˈplājəˌrizəm/

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noun

the practice of taking someone else's work or ideas and passing them off as one's own.

explanation:

a mercury barometer is a device that uses the physical properties of mercury in a tube to measure barometric pressure. mercury barometers are used for : -

1. measurement of atmospheric pressure  

2. determining the altitude of a place

3. weather forecasting

4. calibration and checking of aneroid barometers

5. application in fluid mechanics

6. measurement of pressure in aircrafts

7. surface weather analysis

8. preparation of barographs

9. usage in physical sciences like physics, astronomy & chemistry

10. preparation of aircraft altimeters

characteristics of mercury barometer : -

1.used to define and measure atmospheric pressure.

2.on the average at sea level the column of mercury rises to a height of about 760 mm.

3.this quantity is equal to 1 atmosphere.

4.it is also known as standard atmospheric pressure.

5.a barometer in which the weight of a column of mercury in a glass tube with a sealed top is balanced against that of the atmosphere pressing on an exposed cistern of mercury at the base of the mercury column, the height of the column varying with atmospheric pressure.