Chemistry Past Questions

A gas mixed with oxygen produces a highly exothermic and easily controllable flame reaching temperatures near 3000°C. What is the name of this flame and where is it primarily used?

When 12.5 g of a saturated aqueous solution is heated to complete dryness at 60°C, 2 g of an anhydrous salt residue remains behind. Calculate the solubility of this salt in grams per 100 g of water.

127 g of sodium chloride was dissolved in 1.0 dm₃ of distilled water at 25°C. Determine the solubility in mol?dm-3 of sodium chloride at that temperature. [Na = 23, Cl = 35.5]

By what amount must the temperature of 200cm₃ of Nitrogen at 27°C be increased to double the pressure if the final volume is 150cm₃ (Assume ideality)

The heat of formation of ethene, C₂H₄ is 50 kJmol-1, and that of ethane, C₂H₆ is -82kJmol-1. Calculate the heat evolved in the process: C₂H₄ + H₂ → C₂H₆

When ΔH is negative, a reaction is said to be

Consider the reaction: A + 2B(g) → 2C + D(g) (ΔH = +ve) What will be the effect of decrease in temperature on the reaction?

In the reaction: M + N → P ΔH = +Q kJ Which of the following would increase the concentration of the product?

For a chemical process where ΔG° = - ve, the reaction is deemed thermodynamically feasible and spontaneous. Under what general conditions will a reaction always display feasibility as absolute temperature increases?

For the reaction X(g) + 3Y(g) → 2Z(g) where ΔH is positive, if the process takes place at room temperature without specific magnitude values, ΔG will be:

Consider the spontaneous redox displacement reaction: Mg + Pb?? ? Mg?? + Pb. What is the correct standard cell notation for this electrochemical cell configuration?

The presence of an impurity in a substance will cause its melting point to ________.