Question

which factor most increases the rate of dissolving?
a cooling
b reducing surface area
c increasing particle size
d stirring

Explanation:

• Cooling: Generally, cooling a solution decreases the kinetic energy of the particles, which slows down the dissolving process. For example, sugar dissolves more slowly in cold water compared to hot water.
• Reducing surface area: A smaller surface area means fewer solute particles are in contact with the solvent at a given time. So, reducing the surface area of the solute (e.g., using a large rock - like piece of salt instead of fine salt powder) slows down the dissolving rate.
• Increasing particle size: Larger particles have a smaller surface - area - to - volume ratio. Similar to reducing surface area, this leads to a slower dissolving rate as there is less contact between the solute and the solvent.
• Stirring: Stirring helps to bring fresh solvent into contact with the solute. It increases the movement of solvent molecules around the solute particles, which speeds up the dissolving process. For instance, when making a cup of coffee, stirring the coffee grounds in hot water makes them dissolve faster.

Answer:

D. Stirring