General Chemistry Answers

1. The combustion of benzene is the following reaction:

C₆H₆ (l) + 7.5 O₂ (g) è 6 CO₂ (g) + 3 H₂O (g) Δ H =?

Using Hess’ Law, find the enthalpy change, Δ H, for this reaction by combining these reactions:

 6 C (graphite) + 3 H₂ (g) è C₆H₆ (l)  ΔH = + 49.0 kJ

C (graphite) + O₂ (g) è CO₂ (g)  ΔH = -394 kJ 

H₂ (g) + ½ O₂ (g) è HOH (l)  ΔH = -286 kJ

Using Bond energy reference sheet to calculate Δ H for the balanced reaction below:

C₈H₁₈ (l) + 12.5 O₂ (g) è 8 CO₂ (g) + 9 HOH (g)

Determine the Molarity of a solution made by dissolving 21.6 grams of sodium carbonate, Na₂CO_3, in enough water to make 400.0 ml of solution.

How much acid and water are needed to dilute 12.0 M concentrated hydrochloric acid HCl, to make 4.00 liters of a 3.00 M solution?

How many grams of sodium bicarbonate, NaHCO₃, are needed to make 200.0 ml of a 0.250 M solution?

Calculate the freezing point of a 4.00 molal solution of methanol, CH₃OH.

Determine the boiling point of a 2.00 molal solution of potassium bromide, KBr. 

Calculate the molar mass of a nonelectrolyte if 40.0 grams of it dissolved in 200.0 grams of water lowers the freezing point to – 1.40 ° C.

Determine the Molarity of a solution made by dissolving 21.6 grams of sodium carbonate, Na₂CO_3, in enough water to make 400.0 ml of solution.

Calculate the pressure in a 212 Liter tank containing 23.3 kg of argon gas at 25°C? ( atomic weight Ar - 40 )