Thermochemical Equations Practice
1) Using the balanced thermochemical equation below:
2H2 + O2 + 2H20 + 241.8 kJ
How much heat is released when 12.5 grams of hydrogen (Hz) are
completely reacted?

755.625 kj

Explanation:

Given data:

Heat released by two mole of H₂ = 241.8 Kj

Heat released by 12.5 grams of H₂ = ?

Solution:

Number of moles of hydrogen:

Number of moles = mass/ molar mass

Number of moles = 12.5 g/ 2 g/mol

Number of moles = 6.25 mol

Chemical equation:

2H₂ + O₂  →  2H₂O  + 241.8 kj

Now we will determine the heat released by 6.25 moles of hydrogen.

2 mole = 241.8 kj

1 mole =241.8 kj/2 = 120.9 kj

120.9 kj × 6.25 = 755.625 kj

both adhesion and cohesion are attractions.

they are different in that adhesion is the force of attraction between the molecules of two different substances, whereas cohesion is the force of attraction between molecules of the same substance.

possible examples include capillary action, in which the adhesion between water and glass causes the water to rise in a narrow tube against the force of gravity.

because of hydrogen bonding, water is extremely cohesive.

this causes molecules on the surface of water to be drawn inward, which is why drops of water form beads on smooth surfaces.

hope this .