The rate constant for this first-order reaction is 0.710 s1 at 400 C.

A-> Products

How long (in seconds) would it take for the concentration of A to decrease from 0.820 M to 0.290 M?

1.016 seconds

Explanation:

Let's bring out the parameters we were given in the question;

Rate constant k  = 0.710 s^-1

Initial Concentration [A] = 0.820 M

Final concentration [A]o = 0.290 M

Time t = ?

Formular relating these parameters is given as;

ln[A] = ln[A]o − kt

Making t subject of interest, we have;

ln[A] - ln[A]o = -kt

kt = ln[A]o - ln[A]

t = (ln[A]o - ln[A]) / k

Substituting the values, we have;

t = ( ln(0.820) - ln(0.290) ) / 0.710

t = 0.7217 / 0.710

t = 1.016 seconds

law of conservation of matter

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.