A gas sample occupies a volume of 1.264 L when the temperature is 168.0 °C and the pressure is 946.6 torr. How many molecules are in sample?

0.26×10²³ molecules

Explanation:

Given data:

Volume of gas = 1.264 L

Temperature = 168°C

Pressure = 946.6 torr

Number of molecules of gas = ?

Solution:

Temperature = 168°C (168+273= 441 K)

Pressure = 946.6 torr (946.6/760 = 1.25 atm)

Now we will determine the number of moles.

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

n = PV/RT

n = 1.25  atm ×1.264 L / 0.0821 atm.L/ mol.K   ×441 K

n = 1.58 /36.21 /mol

n = 0.044 mol

Now we will calculate the number of molecules by using Avogadro number.

1 mol = 6.022×10²³ molecules

0.044 mol × 6.022×10²³ molecules/ 1mol

0.26×10²³ molecules

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.