GCSE Chemistry Revision "Concentration of Solutions"

Summary

In this Free Science video, viewers learn how to calculate the concentration of a solution in grams per decimeter cubed. The lesson explains that concentration is the mass of solute per given volume of solution, with water often serving as the solvent. The video demonstrates calculations using a formula and offers practice problems. Higher-tier students also explore how changes in solute mass and solution volume affect concentration, making this an informative resource for understanding chemical solutions.

Takeaways

• 🔍 The concentration of a solution is defined as the mass of solute in a given volume of solution.
• 📚 Higher tier students will learn an additional definition of concentration later, but Foundation students only need to learn this one.
• 💧 A solute is a chemical that is dissolved in a solvent, commonly water in chemistry.
• 🔢 The unit of concentration is grams per decimeter cubed (g/dm³), which is equivalent to grams per liter.
• 📐 The concentration is calculated using the formula: concentration (g/dm³) = mass (g) / volume (dm³).
• 📈 A triangle diagram is used to help remember the formula for calculating concentration.
• 🧪 Example calculation: 200 g of a chemical dissolved in water to a final volume of 1 dm³ results in a concentration of 200 g/dm³.
• 🧐 Challenging calculation: 150 g of a chemical dissolved in water to a final volume of 0.5 dm³ results in a concentration of 300 g/dm³.
• 🔄 The equation can be rearranged to calculate either the mass of a solute or the volume of a solution given the concentration.
• 📉 If the mass of solute is increased while the volume remains constant, the concentration increases.
• 📈 If the volume of the solution is increased while the mass of solute remains constant, the concentration decreases.

Q & A

What is the definition of concentration in the context of this video?

Concentration refers to the mass of a solute in a given volume of solution, expressed in grams per decimeter cubed (g/dm³).

What is a solute in chemistry?

A solute is a chemical that is dissolved in a solvent, with water being a common solvent in chemistry.

What is the unit of concentration used in this video?

The unit of concentration used is grams per decimeter cubed (g/dm³), which is equivalent to grams per liter.

How is concentration calculated according to the video?

Concentration is calculated by dividing the mass of the solute in grams by the volume of the solution in decimeters cubed.

What is the concentration of a solution if 200 g of a chemical is dissolved in water to a final volume of 1 dm³?

The concentration would be 200 g/dm³ since the mass (200 g) divided by the volume (1 dm³) equals 200 g/dm³.

How would you calculate the concentration if 150 g of a chemical is dissolved in water to a final volume of 0.5 dm³?

The concentration would be 300 g/dm³, calculated by dividing the mass (150 g) by the volume (0.5 dm³).

What is the mass of a chemical needed to achieve a concentration of 600 g/dm³ in a final volume of 0.4 dm³?

The mass needed would be 240 g, calculated by multiplying the concentration (600 g/dm³) by the volume (0.4 dm³).

How do you find the final volume of a solution containing 200 g of a chemical with a concentration of 800 g/dm³?

The final volume would be 0.25 dm³, found by dividing the mass (200 g) by the concentration (800 g/dm³).

How does increasing the mass of the solute affect the concentration if the volume of the solution remains the same?

Increasing the mass of the solute while keeping the volume constant will increase the concentration of the solution.

What happens to the concentration if the volume of the solution is increased while the mass of the solute remains the same?

If the volume of the solution is increased and the mass of the solute remains the same, the concentration of the solution will decrease.

What additional resources are available for practicing concentration calculations as mentioned in the video?

The video mentions a revision workbook with more questions on concentration, which can be accessed by clicking on the provided link.

Outlines

00:00

🔬 Introduction to Solution Concentration

The script starts with an introduction to the concept of concentration in chemistry, specifically focusing on how it's calculated in grams per decimeter cubed (g/dm³). It clarifies that for higher tier students, there will be an additional definition of concentration in later videos, but foundation students need only learn this one. The script defines a solute as a chemical dissolved in a solvent, typically water, and explains that the concentration can be calculated using the formula: concentration (g/dm³) = mass (g) / volume (dm³). A visual aid in the form of a triangle is mentioned to help with learning this equation. The script then poses a question to calculate the concentration of a solution with 200 g of a chemical dissolved in water to a final volume of 1 dm³, resulting in a concentration of 200 g/dm³.

🧪 Calculating Concentration with Different Volumes

The script challenges viewers with a more complex question involving a chemical dissolved in water to a final volume of 0.5 dm³, asking to calculate the concentration. The correct answer, obtained by dividing 150 g by 0.5 dm³, is 300 g/dm³. The video then suggests rearranging the concentration equation to calculate either the mass of a solute or the volume of a solution. An example question is given where viewers are asked to calculate the mass of a chemical needed to achieve a concentration of 600 g/dm³ in a final volume of 0.4 dm³. The correct calculation involves multiplying the concentration by the volume, yielding a mass of 240 g.

📚 Advanced Questions on Concentration

The script presents another question for viewers to calculate the final volume of a solution containing 200 g of a chemical with a concentration of 800 g/dm³. The correct approach is to divide the mass by the concentration, resulting in a final volume of 0.25 dm³. The script then explains that higher tier students need to understand how the mass of the solute and the volume of the solution affect the concentration. Two key facts are highlighted: increasing the mass of the solute while keeping the volume constant increases the concentration, and increasing the volume of the solution while keeping the mass of the solute constant decreases the concentration. The video concludes by directing viewers to a revision workbook for more practice questions on concentration.

Keywords

💡Concentration

Concentration in chemistry refers to the amount of solute present in a given volume of solution. It is a measure of how much of a particular substance is mixed with another substance. In the context of the video, concentration is defined as the mass of solute in a given volume of solution, expressed in grams per decimeter cubed (g/dm³). The video emphasizes the importance of understanding concentration for solving chemistry problems, such as calculating the mass of a solute needed to achieve a certain concentration or determining the volume of a solution given the mass of solute and desired concentration.

💡Solute

A solute is a substance that is dissolved in a solvent to form a solution. It is the component of the mixture that is present in a smaller amount. In the video, the solute is a chemical that is dissolved in water, which acts as the solvent. The script uses the example of dissolving 200g of a chemical in water to illustrate how to calculate the concentration of the resulting solution.

💡Solvent

A solvent is a substance, usually a liquid, that has the ability to dissolve other substances (solutes). Water is commonly used as a solvent in chemistry. The video mentions water as the solvent in which the solute is dissolved, emphasizing its role in creating the solution.

💡Decimeter Cubed (dm³)

Decimeter cubed (dm³) is a unit of volume that was historically equivalent to a liter. In the video, dm³ is used to express the volume of the solution when calculating concentration. The script clarifies that scientists no longer use the term 'liter' and instead use 'decimeter cubed' or 'cubic decimeter'.

💡Mass

Mass in the context of the video refers to the amount of matter in an object, typically measured in grams (g). It is a key component in calculating the concentration of a solution, as the mass of the solute is divided by the volume of the solution to find the concentration. The video provides examples of how to calculate concentration using the mass of a solute and the volume of the solution.

💡Volume

Volume is the amount of space that a substance or object occupies, and in the video, it is crucial for calculating the concentration of a solution. The script explains how to calculate the volume of a solution given the mass of the solute and the desired concentration, using the formula volume = mass / concentration.

💡Higher Tier Students

Higher tier students, as mentioned in the video, are those studying at a more advanced level. They are expected to understand additional concepts related to concentration beyond the basic definition. The video suggests that these students will learn another definition of concentration in a later video, indicating a deeper exploration of the topic.

💡Equation

The equation mentioned in the video is used to calculate the concentration of a solution. It is expressed as concentration (g/dm³) = mass (g) / volume (dm³). The video emphasizes the importance of understanding and applying this equation to solve problems related to solution concentration.

💡Rearranging Equation

Rearranging the equation is a mathematical technique used in the video to solve for different variables involved in concentration calculations. For example, to find the mass of a solute needed for a certain concentration, the equation is rearranged to mass = concentration × volume. The video provides examples of how to rearrange the equation to solve for mass and volume.

💡Concentration Effects

The video discusses how changes in the mass of the solute and the volume of the solution affect the concentration. It explains that increasing the mass of the solute while keeping the volume constant will increase the concentration, and increasing the volume while keeping the mass constant will decrease the concentration. These effects are crucial for higher tier students to understand the dynamic nature of solution concentration.

💡Revision Workbook

The revision workbook mentioned in the video is a resource for additional practice questions on concentration. It is suggested as a tool for students to reinforce their understanding of the concept through problem-solving. The script implies that the workbook contains a variety of questions to help students apply their knowledge of concentration.

Highlights

Introduction to calculating the concentration of a solution in grams per decimeter cubed

Explanation for higher tier students about additional concentration definitions

Definition of solute and solvent in chemistry

Concentration unit is grams per decimeter cubed, formerly known as grams per liter

Concentration calculation formula: mass in grams divided by volume in decimeters cubed

Visual aid in the form of a triangle to help memorize the concentration formula

Example calculation: 200 g of a chemical dissolved in water to a final volume of 1 DM cubed

Result of the example calculation: concentration of 200 g per decimeter cubed

Challenger question: calculating concentration with 150 g of a chemical dissolved in 0.5 DM cubed

Result of the challenging calculation: concentration of 300 g per decimeter cubed

Instruction on rearranging the concentration equation to find mass or volume

Example problem: calculating the mass needed for a specific concentration and volume

Solution to the example problem: multiplying concentration by volume to find mass

Another example problem: calculating the final volume of a solution with a given mass and concentration

Solution to the volume calculation: dividing mass by concentration

Explanation for higher tier students on how mass and volume affect concentration

Two key facts for higher tier students regarding concentration changes

Availability of more concentration questions in the revision workbook

Summary of the lesson's learning objectives

Transcripts

[Music]

hi and welcome back to free science

lessons. co.uk by the end of this video

you should be able to calculate the

concentration of a solution in grams per

desm cubed higher tier students should

also be able to explain how the mass of

the solute and the volume of the

solution affect the

concentration so let's start by looking

at what's meant by concentration the

concentration tells us the mass of a

solute in a given volume of solution now

I should point out that if you're a

higher tier student you learn another

definition of concentration as well as

this one in a later video but if you're

doing Foundation then you only need to

learn this

definition so what's meant by a solute

well a solute is a chemical which is

dissolved in a solvent and in chemistry

water is often used as a

solvent the unit of concentration for

this definition is G per decim cubed a

cubed is what used to be called a liter

but scientists don't use that word

anymore now we calculate the

concentration using this equation this

equation is not in the spec but I do

think it's worth learning the

concentration in grams per decimeter

cubed is the mass in grams divided by

the volume in decimet cubed and here's a

triangle to help you learn

this so let's look at a typical question

200 g of a chemical is dissolved in

water to a final volume of 1 DM cu cubed

calculate the concentration of the

solution here's the

equation to find the concentration we

divide the mass and grams by the volume

in decimet cubed this gives us a final

concentration of 200 g per decim cubed

now that was quite an easy one so let's

look at something a bit more

challenging 150 g of a chemical is

dissolved in water to a final volume of

0.5 DM cubed calculate the concentration

of the solution pause the video and try

this

yourself okay dividing 150 G by 0.5 DM

cubed gives us a final concentration of

300 G per decim

cubed okay now in the exam you could be

asked to rearrange this equation and

calculate the mass of a solute or the

volume of a solution so here's another

question for you to

try calculate the mass of a chemical

needed to dissolve in a final volume of

0.4 DM cubed to give a concentration of

600 G per per decim cubed now to answer

this question it's worth using the

triangle pause the video and try this

yourself we're calculating Mass so we

multiply the concentration by the volume

multiplying 600 by .4 gives us a final

mass of 240

G here's one more question for you to

try calculate the final volume of a

solution containing 200 g of a chemical

with a concentration of 800 G per decim

cubed here's a triangle pause the video

and try this

yourself okay we're calculating the

volume so we need to divide the mass by

the

concentration 200 g ID 800 G per decim

cubed gives us a final volume of .25

decim

cubed now if you're a higher student you

need to be able to explain how the mass

of the solute and the volume of the

solution affect the

concentration here are the two facts

that you need to know if we increase the

mass of solute and keep the volume the

same then we increase the

concentration if we increase the volume

of the solution and keep the mass of the

solute the same then we decrease the

concentration remember that you'll find

plenty more questions on concentration

in my revision workbook which you can

get by clicking on the link

above okay so hopefully now you should

be able to calculate the concentration

of a solution and grams per decimeter

cubed and if you're a higher tier

student you should be able to explain

how the mass of the solute and the

volume of the solution affect the

[Music]

concentration