Indicate whether each statement is true or false: (a) If you...

Indicate whether each statement is true or false: (a) If you compare the solubility of a gas in water at two different temperatures, you find the gas is more soluble at the lower temperature. (b) The solubility of most ionic solids in water decreases as the temperature of the solution increases. (c) The solubility of most gases in water decreases as the temperature increases because water is breaking its hydrogen bonding to the gas molecules as the temperature is raised. (d) Some ionic solids become less soluble in water as the temperature is raised.

Indicate whether each statement is true or false:
(a) If you compare the solubility of a gas in water at two different temperatures, you find the gas is more soluble at the lower temperature.
(b) The solubility of most ionic solids in water decreases as the temperature of the solution increases.
(c) The solubility of most gases in water decreases as the temperature increases because water is breaking its hydrogen bonding to the gas molecules as the temperature is raised.
(d) Some ionic solids become less soluble in water as the temperature is raised.

Key Concepts

Gas Solubility in Liquids

The solubility of gases in liquids is generally dependent on temperature. Typically, gas dissolution in water is an exothermic process, meaning that lower temperatures favor the dissolution of gas molecules into the liquid, while higher temperatures tend to reduce gas solubility as the process shifts to favor the escape of gas molecules.

Ionic Solid Solubility in Water

The solubility of ionic compounds in water is influenced by the thermodynamics of the dissolution process. Depending on whether the dissolution is endothermic or exothermic, the solubility of an ionic solid may either increase or decrease with temperature changes. This variability explains why some ionic solids dissolve better at higher temperatures while others are more soluble at lower temperatures.

Thermodynamics of Dissolution

Understanding solubility involves considering the energy changes that occur during the dissolution process. Exothermic dissolution releases heat and is typically less favorable at higher temperatures, leading to decreased solubility, whereas endothermic dissolution absorbs heat and often results in increased solubility as temperature rises. This balance of enthalpy and entropy changes is key to predicting how solubility behaves with temperature.

Transcript

00:01 Hello and welcome back.

00:02 We are in chapter 13 now starting problem 36.

00:06 We're going to indicate whether a statement is true or false.

00:09 And what we're looking at is solubility today.

00:12 So a, if you compare the solubility of a gas in water at two different temperatures, you find a gas is more soluble at a lower temperature.

00:20 So let's think about that.

00:21 We have a gas going into solution.

00:32 So we need something from a gas going into a liquid phase.

00:36 So it's out here, particles in the air, and it needs to be in here.

00:39 What has to happen? if temperature goes up, what happens to liquid? liquid becomes a gas.

00:49 As temperature goes down, you've got gases becoming a liquid.

00:55 So this absolutely makes sense.

00:57 So if you compare the solubility of a gas in water at two different temperatures, we find that gas is more soluble at lower temperatures.

01:05 That's absolutely correct.

01:07 That's what we found as well.

01:08 The trend is at lower temperatures, gas is definitely more soluble.

01:16 So that's true.

01:18 Let's look our next problem now.

01:20 The solubility of most ionic solids in water decreases as the temperature of the solution increases.

01:27 So let's look at this now.

01:30 We have a solid and that solid is going into water.

01:39 Perfect.

01:40 This is like sodium hydroxide.

01:43 Any salt we want to dump into water and we want it to break down.

01:46 So let's think about temperature again.

01:48 If we boil that water, increase that temperature, is a solid going to go into solution more? absolutely.

01:55 We're going to have a lot more solids going into liquid state.

01:58 We lower that temperature.

02:01 It's going to be much more difficult for a solid to go into liquid.

02:06 Not saying it's impossible by any stretch of the imagination, just saying it's more difficult.

02:11 The solubility is going to go down as temperature goes down.

02:14 Which is the exact opposite that we found up here with a gas into liquid.

02:19 So watch out when they say these things.

02:21 You've got a solid in water and the solubility of most ionics in water decreases...

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