rate of dissolving

temperature

The temperature of the solvent is another factor that affects how fast a solute dissolves. Generally, a solute dissolves faster in a warmer solvent than it does in a cooler solvent because particles have more energy of movement. For example, if you add the same amount of sugar to a cup of hot tea and a cup of iced tea, the sugar will dissolve faster in the hot tea.

particle size

A third factor that affects the rate of dissolving is the size of solute particles. For a given amount of solute, smaller particles have greater surface area. With greater surface area, there can be more contact between particles of solute and solvent. For example, if you put granulated sugar in a glass of iced tea, it will dissolve more quickly than the same amount of sugar in a cube (see Figure 1.1). Thats because all those tiny particles of granulated sugar have greater total surface area than a single sugar cube.

textbook_image

factors that affect the rate of dissolving

Did you ever get impatient and start drinking a sweetened drink before all the sugar has dissolved? As you drink the last few drops, you notice that some of the sugar is sitting on the bottom of the container. Q: What could you do to dissolve the sugar faster? A: The rate of dissolving is influenced by several factors, including stirring, temperature of solvent, and size of solute particles.

stirring

Stirring a solute into a solvent speeds up the rate of dissolving because it helps distribute the solute particles throughout the solvent. For example, when you add sugar to iced tea and then stir the tea, the sugar will dissolve faster. If you dont stir the iced tea, the sugar may eventually dissolve, but it will take much longer.

instructional diagrams

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questions

if you stir a solute into a solvent

a) more solute will dissolve.

b) the solution will be more concentrated.

-->  c) the solute will dissolve more quickly.

d) all of the above

sugar will dissolve more quickly in ice tea than in hot tea.

a. true

-->  b. false

you could speed up the rate of salt dissolving in a bottle of water by shaking the bottle.

-->  a. true

b. false

if you stir a mixture long enough, you can dissolve any amount of solute in a given solvent.

a. true

-->  b. false

diagram questions

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