Answer:
Intermolecular forces are the forces of attraction or repulsion which act between neighboring particles (atoms, molecules, or ions ). These forces are weak compared to the intramolecular forces, such as the covalent or ionic bonds between atoms in a molecule.
Importance:
Intermolecular forces are important because they determine the physical properties of substances. Many of the life-sustaining properties of water such as its high heat capacity are a result of the hydrogen bonding capabilities it has and are thus due to intermolecular forces.
Volume<span> of matter </span>decreases<span> under </span>pressure<span> ... -under </span>pressure<span>, the </span>particles<span> in a </span>gas<span> are </span>forced closer together<span> ... </span>factors<span> affecting </span>gas pressure<span> ... -</span>if pressure<span> in a sealed container is </span>lower than<span> outside, </span>gas will<span> rush in ...</span>
First a balanced reaction equation must be established:

→

Now if mass of aluminum = 145 g
the moles of aluminum = (MASS) ÷ (MOLAR MASS) = 145 g ÷ 30 g/mol
= 4.83 mols
Now the mole ratio of Al : O₂ based on the equation is 4 : 3
[
4Al +
3 O₂ → 2 Al₂O₃]
∴ if moles of Al = 4.83 moles
then moles of O₂ = (4.83 mol ÷ 4) × 3
=
3.63 mol (to 2 sig. fig.)
Thus it can be concluded that
3.63 moles of oxygen is needed to react completely with 145 g of aluminum.
Answer:
The temperature change from the combustion of the glucose is 6.097°C.
Explanation:
Benzoic acid;
Enthaply of combustion of benzoic acid = 3,228 kJ/mol
Mass of benzoic acid = 0.570 g
Moles of benzoic acid = 
Energy released by 0.004667 moles of benzoic acid on combustion:

Heat capacity of the calorimeter = C
Change in temperature of the calorimeter = ΔT = 2.053°C



Glucose:
Enthaply of combustion of glucose= 2,780 kJ/mol.
Mass of glucose=2.900 g
Moles of glucose = 
Energy released by the 0.016097 moles of calorimeter combustion:

Heat capacity of the calorimeter = C (calculated above)
Change in temperature of the calorimeter on combustion of glucose = ΔT'



The temperature change from the combustion of the glucose is 6.097°C.
Answer:
Actually, The Henderson - Hasselbalch equation allows you to calculate the pH of the buffer by using the pKa of the weak acid and the ratio that exists between the concentrations of the weak cid and conjugate base. The pKa of formic acid is equal to 3.75. In this case, the pH of the solution will be equal to the acid's pKa .