Solubility Calculations

Summary

This educational video script focuses on solubility calculations, emphasizing the impact of temperature on solubility. It uses sodium chloride as an example to demonstrate how to calculate molar solubility and determine if a solution is saturated or unsaturated. The script guides viewers through converting grams to moles, calculating solubility in different volumes, and comparing solubility ratios to assess solution saturation. It concludes by illustrating how to determine if additional solute can be dissolved to reach saturation.

Takeaways

• 🔍 The video focuses on solubility calculations, emphasizing the importance of understanding molar solubility and its dependence on temperature.
• ⚖️ Molar solubility is defined as the number of moles of solute that can dissolve in one liter of solvent, which is a measure of molarity.
• 🌡️ Temperature can significantly affect solubility, with some compounds becoming more soluble at higher temperatures and less soluble at lower temperatures.
• 🔢 All calculations in the video are conducted at a standard temperature of 20 degrees Celsius, where temperature's effect on solubility is neutralized.
• 🧂 The example used throughout the video is sodium chloride, with a solubility of 360 grams per liter in water.
• 🧪 To calculate molar solubility, one must convert grams of solute to moles using the molar mass, which for sodium chloride is 58.44 grams per mole.
• ➗ When determining how many grams will dissolve in a different volume, such as 300 milliliters, a proportion based on the solubility in liters is used.
• 📏 To find out the volume required to dissolve a certain mass of solute, the process involves setting up a ratio and solving for the unknown volume.
• 💧 Understanding whether a solution is saturated or unsaturated is crucial; a saturated solution contains the maximum amount of solute that can dissolve at a given temperature.
• 🔄 The video also touches on how to determine if additional solute can be dissolved in a solution to reach saturation, using solubility ratios for calculation.

Q & A

What is molar solubility?

Molar solubility is a term used to describe the solubility of a substance in terms of molarity, which is the number of moles of solute per liter of solution.

How does temperature affect solubility?

Temperature can increase or decrease the solubility of a compound. Generally, increasing the temperature can make a substance more soluble, while decreasing it can make it less soluble.

At what temperature are the calculations in the video example performed?

The calculations in the video example are performed at 20 degrees Celsius, as temperature is not a factor in these specific calculations.

What is the solubility of sodium chloride in water according to the video?

The solubility of sodium chloride in water is given as 360 grams per one liter.

How can you convert grams of sodium chloride to moles?

To convert grams of sodium chloride to moles, you divide the number of grams by the molar mass of sodium chloride, which is 58.44 grams per mole.

What is the molar solubility of sodium chloride in moles per liter?

The molar solubility of sodium chloride is 6.16 moles per liter, calculated by dividing 360 grams by the molar mass of 58.44 grams per mole.

How many grams of sodium chloride will dissolve in 300 milliliters of water?

108 grams of sodium chloride will dissolve in 300 milliliters of water, based on the solubility ratio provided.

How many milliliters of water are needed to dissolve 13.6 grams of sodium chloride?

37.78 milliliters of water are needed to dissolve 13.6 grams of sodium chloride, as calculated using the solubility ratio.

What does it mean for a solution to be saturated?

A solution is considered saturated when it contains the maximum amount of solute that can dissolve at a given temperature and pressure.

How can you determine if a solution of sodium chloride is saturated or unsaturated?

You can determine if a solution is saturated or unsaturated by comparing the ratio of grams of solute to milliliters of solvent in the solution to the solubility ratio. If the ratio is less than the solubility ratio, the solution is unsaturated; if it's equal, it's saturated.

Outlines

00:00

🧪 Understanding Molar Solubility and Temperature Effects

This paragraph introduces the concept of molar solubility, which is synonymous with molarity, and explains how it is measured in moles per liter. It emphasizes the role of temperature in affecting solubility, noting that it can either increase or decrease a compound's solubility. The video will focus on calculations at a constant temperature of 20 degrees Celsius, where temperature's impact on solubility is not a factor in the calculations. The example of sodium chloride with a solubility of 360 grams per liter in water is used to demonstrate how to calculate molar solubility by converting grams to moles using the molar mass of sodium chloride (58.44 g/mol), resulting in a molar solubility of 6.16 moles per liter or 6.16 M.

05:01

📏 Calculating Solubility in Different Volumes

The second paragraph delves into practical calculations of solubility. It demonstrates how to determine the amount of sodium chloride that will dissolve in 300 milliliters of water, using a proportion based on the solubility in one liter (360 grams). By setting up a ratio and cross-multiplying, the calculation shows that 108 grams of sodium chloride can dissolve in 300 milliliters. The paragraph then explores the inverse problem of calculating the volume of water needed to dissolve a fixed amount of solute (13.6 grams of sodium chloride), resulting in the need for 37.78 milliliters of water. Lastly, it discusses how to assess whether a solution is saturated or unsaturated by comparing the given concentration to the solubility limit, using the example of 100 grams in 600 milliliters versus the solubility of 360 grams per liter.

10:02

🔍 Advanced Solubility Calculations and Applications

The final paragraph extends the discussion on solubility calculations by considering scenarios where one might need to determine if additional solute can be dissolved to reach saturation. It suggests that the methods introduced can be used not only to identify whether a solution is saturated or unsaturated but also to calculate the exact amount of solute needed to achieve a saturated state. This paragraph reinforces the versatility of solubility calculations in understanding and manipulating chemical solutions.

Keywords

💡Molar Solubility

Molar solubility refers to the maximum amount of a solute that can be dissolved in a solvent at a given temperature to form a saturated solution, expressed in terms of moles per liter. In the video, molar solubility is used to calculate how many moles of sodium chloride can be dissolved in one liter of water, which is a key concept for understanding solubility calculations. The example given is the solubility of sodium chloride at 360 grams per liter, which is then converted into moles per liter to find the molar solubility.

💡Temperature

Temperature is a critical factor that can affect the solubility of a compound. The video mentions that temperature can either increase or decrease the solubility of a substance. While the calculations in the video are standardized at 20 degrees Celsius and temperature does not directly influence the calculations, it's important to recognize that in different contexts, temperature changes could alter the solubility, thus affecting the outcomes of solubility-related problems.

💡Molarity

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. In the context of the video, molarity is used synonymously with molar solubility, as it helps to determine the concentration of a solute in a solution. The video uses the molarity concept to calculate the molar solubility of sodium chloride, which is a fundamental step in solubility calculations.

💡Molar Mass

Molar mass is the mass of one mole of a substance, measured in grams per mole (g/mol). It is used to convert the mass of a substance into the number of moles. In the video, the molar mass of sodium chloride is calculated by adding the atomic masses of sodium (22.99 g/mol) and chlorine (35.45 g/mol) to find the total molar mass of 58.44 g/mol, which is then used to convert grams of sodium chloride into moles for solubility calculations.

💡Conversion

Conversion in the context of the video refers to the process of changing units or forms of a measurement to match the required units for a calculation. An example from the script is converting grams to moles by using the molar mass, or converting liters to milliliters to ensure consistency in volume units when calculating solubility in different volumes.

💡Ratio

A ratio is a relationship between two numbers that indicates how many times one number contains or is contained within the other. In the video, ratios are used to compare the solubility of sodium chloride in different volumes of water. For instance, the ratio of grams of sodium chloride to milliliters is used to determine how many grams will dissolve in a given volume, or how many milliliters are needed to dissolve a certain amount of grams.

💡Saturated Solution

A saturated solution is a solution in which the maximum amount of solute has been dissolved in the solvent at a given temperature. The video discusses how to determine if a solution is saturated by comparing the amount of solute present to the solubility limit. If the ratio of solute to solvent is less than the solubility ratio, the solution is unsaturated; if it's equal, the solution is saturated.

💡Unsaturated Solution

An unsaturated solution is one in which there is less solute dissolved than the maximum amount that the solvent can hold at a given temperature. The video explains how to identify an unsaturated solution by comparing the solubility of a solute in a given volume to the known solubility limit. If the solution contains less solute than the solubility limit, it is unsaturated, indicating that more solute could be dissolved.

💡Cross Multiply

Cross multiplication is a method used in solving proportions or ratios, where the products of the cross terms are set equal to each other. In the video, cross multiplication is used to solve for the unknown amount of solute or solvent in solubility problems, such as finding out how many grams of sodium chloride will dissolve in a certain volume of water or how much water is needed to dissolve a certain amount of solute.

💡Solubility

Solubility is the ability of a solid, liquid, or gaseous solute to dissolve in a solvent. In the video, solubility is the central theme, with a focus on calculating the solubility of sodium chloride in water. The script provides examples of how to calculate molar solubility, determine the amount of solute that can dissolve in a given volume, and assess whether a solution is saturated or unsaturated based on its solubility.

Highlights

Introduction to solubility calculations and the importance of understanding molar solubility and how temperature affects solubility.

Explanation that all calculations in the video will be performed at 20 degrees Celsius, where temperature's effect on solubility is neutral.

Example using sodium chloride with a solubility of 360 grams per liter in water to demonstrate molar solubility calculation.

Conversion of grams to moles using the molar mass of sodium chloride to find molar solubility.

Calculation resulting in a molar solubility of 6.16 moles per liter for sodium chloride.

How to determine the amount of sodium chloride that will dissolve in 300 milliliters of water.

Use of proportionality to calculate solubility in different volumes, resulting in 108 grams dissolving in 300 milliliters.

Method to find out how many milliliters are needed to dissolve a specific amount of solute, using 13.6 grams of sodium chloride as an example.

Cross-multiplication technique used to solve for the volume required to dissolve a given mass of solute.

Result of needing 37.78 milliliters to dissolve 13.6 grams of sodium chloride.

Discussion on determining if a solution is saturated or unsaturated by comparing the given ratio to the solubility ratio.

Calculation showing that a solution with 100 grams of sodium chloride in 600 milliliters is unsaturated.

Comparison of the solubility ratio to the given ratio to determine the solution's saturation state.

Potential to use the calculated ratios to find out how many more grams could be dissolved to reach saturation.

Summary of the different calculations that can be performed using solubility to understand solution saturation.

Transcripts

so in this video we're going to look at

solubility calculations and Before we

jump into our examples there are a

couple of things that we need to make

note of first and the first is two terms

which are molar solubility and at a

temperature so when we're looking at

salt molar solubility that's just

another way of saying molarity which

means we're gonna be looking at moles

over liters now when we say that these

things are soluble at a certain

temperature

that's because temperature can increase

or decrease the solubility of a compound

so temperature can increase or decrease

the solubility now that just means that

if you increase the temperature it can

become more soluble if you decrease the

temperature it can become less soluble

all of our calculations are going to be

at done at 20 degrees Celsius Celsius so

the temperature doesn't really matter

it's not going to play into our

calculations it's just important to note

that temperature can alter the

solubility of something so now we're

gonna come back and we're gonna look

through four different examples we're

gonna start with this one up here at the

top so this says the solubility of

sodium chloride in water is 360 grams

per one liter we're actually gonna use

sodium chloride in water as our example

for all of our calculations that we're

gonna do in this video so the first

question that we're gonna look at is

just calculating this molar solubility

so again like I said molar solubility

we're really just looking at molarity

which is moles divided by liters now if

I look at my solubility that I'm given

up here I already have liters so that's

good but I need to convert my grams into

moles so I can get my moles units that I

need for my molarity calculation so in

order to convert grams into grams into

moles I need my molar mass okay so

that's my first calculation I'm going to

do I'm gonna find my molar mass of

sodium chloride so we've done this

before we're gonna use our

ah to cable sodium is twenty two point

nine nine zero chlorine is thirty five

point four five you add those up and you

get fifty eight point four four grams

per mole now if I'm going from grams to

moles I'm gonna divide by my molar mass

so I'm going to take my three hundred

and sixty grams I'm going to divide it

by my fifty eight point four four which

is my molar mass of sodium chloride so I

do 360 divided by fifty eight point four

whoops 360 divided by fifty eight point

four four and you get six point one six

moles so when I'm asking about my molar

solubility molar solubility as moles per

liter

I converted my grams into moles so it's

six point one six moles per one liter we

could also say it's six point one six

molar so that's one way that it's

similar to concentration but molar

solubility is the same thing as moles

divided by liters so that one was pretty

easy so now we're gonna come over here

and we're gonna do example number two

so again still working with sodium

chloride so it's 360 grams in one liter

in this case in this question I want to

know how many grams are gonna dissolve

in three hundred milliliters so before I

actually answer the question I need to

look at my volume units so my solubility

is given in grams per liter my question

is asking about milliliters so I need to

make sure that those are the same so I'm

just gonna rewrite this as 360 grams per

1,000 milliliters and that's just

because one liter equals a thousand

milliliters so I'm just writing it

differently I don't have to actually

divide those numbers I'm just writing it

so that my units match now we're going

to use these as a ratio so we have X

number of grams in 300 milliliters is

equal to three

160 grams in 1,000 milliliters so our

solubility is the Maxima or what we're

looking at that's how much possible we

can dissolve in a certain volume so I

know that I can dissolve up to 360 grams

and a thousand milliliters so I want to

know how many grams I can dissolve in

300 milliliters so we can then cross

multiply so this is pretty

straightforward so we have so we have X

grams times a thousand milliliters

equals 300 milliliters times 360 grams X

grams times a thousand milliliters oops

so now I'm just solving for x so I'm

gonna do 300 times 360 and I get 108

thousand milliliters times grams so then

I'm going to divide by a thousand

milliliters on both sides and I need a

little bit more space so there we go

so one two three I get 108 grams that I

can dissolve in 300 milliliters so

that's it

pretty straightforward okay so now we're

gonna look at a different question

similar but a little bit different this

is actually kind of the opposite style

of question so still looking at

solubility of sodium chloride 360 grams

in one liter but in this case I want to

know how many milliliters is it going to

take to dissolve 13.6 grams of sodium

chloride

okay so again I need to make sure that

my volume units matched so I'm going to

rewrite this as 360 grams in a thousand

milliliters again I can do that because

one liter is the same as a thousand

milliliters and in this case I know my

grams so I have thirteen point six grams

per X milliliters and then I

360 grams per a thousand milliliters I'm

gonna cross multiply so this is the same

style of solving that we did before so

we have X milliliters times 360 grams

equals 13 point 6 grams times a thousand

milliliters so now we're just solving

for x probably don't need to type that

in my calculator but just want to make

sure I get the right numbers and then

solve for x by dividing both sides by

360 grams so I do one three six zero

zero divided by whoops top my zero there

360 gets me 37 point seven eight

milliliters so if I'm gonna dissolve

13.6 grams

I need 37 point seven eight milliliters

in order to do that so similar style as

the previous question just solving for

something different okay we have one

more problem that we're gonna look at

where's my problem there it is okay in

this question still using sodium

chloride still has a solubility of 360

grams in one liter in this case we want

to decide if something is saturated or

unsaturated so saturated meaning that we

can have the max amount of solute and

unsaturated meaning we have less than

the max

okay so if something is saturated it's

going to have the solubility of 360

grams per one liter so what we're gonna

do is we're gonna find our ratio that I

gave you in the problem so 100 grams and

600 milliliters and we're going to

compare that to our solubility ratio of

360 grams per one liter so I'm gonna do

my 100 grams in 600 milliliters so when

I do 100 divided by a 600 I get 0.16

seven grams per milliliter and then I'm

gonna do my 360 grams in a thousand

milliliters again I'm rewriting this

just because one liter equals a thousand

milliliters

oops keep dropping my zeros so if I do

360 divided by 1,000 I get 0.36 zero

grams per milliliter so I'm gonna

compare these two numbers since the

amount given in the problem is less than

the max so it's less than the solubility

it means it is unsaturated if it was the

same as the solubility that means it

would be saturated so since this is

unsaturated it's less than our

solubility and we could also use this to

figure out how many more grams we could

dissolve if that was something that the

question asks this question just asked

is it saturated or unsaturated but from

here we could determine how many more

grams we would need to dissolve in order

to reach a saturated solution so those

are just several different ways that we

can use solubility to do a variety of

different calculations