Preparing a soluble salt | 14–16 Practicals
Summary
TLDRThe video demonstrates how to safely prepare copper sulfate crystals in a laboratory setting. It explains the key steps, including heating sulfuric acid, adding copper oxide, and filtering the solution. The presenter highlights safety precautions, such as using safer heating methods and wearing protective gear. The video also discusses the chemical reactions involved, particularly the neutralization of acid by a base. By following these instructions, viewers can create well-formed copper sulfate crystals and are encouraged to experiment with making other soluble salts while prioritizing safety.
Takeaways
- 🧂 Sodium chloride, or table salt, is a well-known example of a salt and has been historically used for preserving meat, cleaning wounds, and making soap.
- 🔬 In chemistry, salts are ionic compounds formed by the neutralization of an acid by a base. Sodium chloride is just one of many types of salts.
- 🧪 The process described in the script is about preparing a different salt: copper sulfate.
- 📚 The name of the salt has two parts: the first part comes from the metal, metal oxide, or metal carbonate, while the second part comes from the acid used in the reaction.
- 🛑 Safety is crucial, and the script emphasizes using safer methods, such as warming sulfuric acid in hot water instead of using a Bunsen burner.
- 🥽 Eye protection is mandatory throughout the experiment, and precise measurements are important for success.
- ⚗️ The experiment involves neutralizing sulfuric acid with copper oxide to form copper sulfate and water, ensuring the reaction is complete by adding excess copper oxide.
- 🚰 Filtration is used to separate the copper sulfate solution from the unreacted copper oxide, with fluted filter paper to improve the process.
- 🔥 Evaporation is used to concentrate the copper sulfate solution, with precautions to avoid overheating, and anti-bumping granules are added to maintain smooth boiling.
- 💎 If left to cool slowly, well-formed copper sulfate crystals can grow overnight. The experiment can be adapted to create other salts like copper chloride or zinc sulfate.
Q & A
What is the primary component of common table salt?
-The primary component of common table salt is sodium chloride.
How has salt been used by humans throughout history?
-Throughout history, humans have used salt to preserve meat, clean wounds, and make soap.
In chemistry, what does the term 'salt' refer to?
-In chemistry, the term 'salt' refers to a group of ionic compounds formed by the neutralization of an acid by a base.
What salt is being prepared in the experiment described in the video?
-In the experiment, the salt being prepared is copper sulfate.
How are the names of salts typically structured?
-The name of a salt has two parts: the first part comes from the metal, metal oxide, or metal carbonate, and the last part comes from the acid used.
Why is the method of heating sulfuric acid in hot water safer than using a Bunsen burner?
-Heating sulfuric acid in hot water is safer because it minimizes the risk of knocking over hot sulfuric acid or having it spill over during the reaction due to rapid reactions.
Why is excess copper oxide used in the reaction with sulfuric acid?
-Excess copper oxide is used to ensure the reaction is complete and that all of the acid has been neutralized.
How is copper sulfate separated from the unreacted copper oxide?
-Copper sulfate is separated from the unreacted copper oxide by filtration, using fluted filter paper.
What are anti-bumping granules used for in the experiment?
-Anti-bumping granules are used to maintain a smooth boiling action without reacting with the particles in the flask.
What should you do if the solution starts spitting or popping during evaporation?
-If the solution starts spitting or popping, you should turn off the heat immediately and never let the solution boil dry.
Outlines
🔬 Understanding Salt and Introduction to Copper Sulfate Preparation
This paragraph introduces salt as sodium chloride, an essential nutrient and a widely recognized compound. The term 'salt' in chemistry is explained as a group of ionic compounds formed by neutralizing acids with bases, with sodium chloride being just one example. The focus then shifts to the preparation of copper sulfate, describing it as a common and rewarding experiment. The salt’s name derives from its metal or acid components. While the process seems straightforward, numerous incidents are reported each year, prompting the use of safer methods in the lab. The paragraph concludes with the safety step of wearing eye protection and preparing sulfuric acid to begin the experiment.
🧪 Safer Method for Heating Sulfuric Acid and Mixing Copper Oxide
This paragraph details the safer approach to heating sulfuric acid by placing the boiling tube in hot water rather than using a Bunsen burner. It walks through the process of preparing the base by measuring copper oxide powder, gradually adding it to the acid, and stirring the mixture. The importance of this method lies in minimizing risks such as spilling hot acid or rapid reactions causing spillage. The chemical reaction is described as a neutralization where copper oxide reacts with sulfuric acid to form copper sulfate and water. Excess copper oxide ensures all the acid is neutralized.
🧹 Filtering and Removing Insoluble Copper Oxide
In this section, the unreacted copper oxide is filtered out of the copper sulfate solution using fluted filter paper. The process of folding the filter paper and setting up a filtration system with a funnel and conical flask is outlined. As the copper sulfate solution filters through, the black copper oxide remains in the paper as residue. This step is crucial to separate the soluble copper sulfate from the insoluble oxide.
🔥 Evaporation and Formation of Copper Sulfate Crystals
The focus here is on evaporating the filtered solution to concentrate the copper sulfate. Anti-bumping granules are added to ensure a smooth boiling process, and the Bunsen burner is turned on. The solution must simmer gently without boiling dry, as overheating could cause spitting or popping. The hot solution is carefully poured into an evaporating dish, and a wooden spill can be used to speed up crystal formation. The paragraph highlights the result: well-formed copper sulfate crystals. However, the crystals should not be taken home due to their hazardous nature.
🔧 Experiment Variations and Safety Precautions
This final paragraph encourages viewers to apply the same steps to create other soluble salts, such as copper chloride or zinc sulfate. The emphasis is on selecting the appropriate reactants and making a thorough risk assessment before beginning any experiment. The video ends with an invitation to use additional resources for designing experiments, reminding viewers to adhere to safety guidelines and to have fun while experimenting.
Mindmap
Keywords
💡Sodium chloride
💡Neutralization
💡Copper sulfate
💡Filtration
💡Crystallization
💡Sulfuric acid
💡Copper oxide
💡Evaporation
💡Anti-bumping granules
💡Safety precautions
Highlights
Sodium chloride, commonly known as salt, is a key nutrient and has been used throughout history for preserving food, cleaning wounds, and making soap.
In chemistry, the term 'salt' refers to a group of ionic compounds formed by the neutralization of an acid by a base, with sodium chloride being just one example.
The name of a salt has two parts: the first comes from the metal, metal oxide, or metal carbonate, while the second part comes from the acid.
This experiment involves preparing copper sulfate, a soluble salt, through a practical method that emphasizes safety and correct procedures.
Heating sulfuric acid using hot water from a kettle is a safer method compared to using a Bunsen burner, as it reduces the risk of spills and accidents.
The reaction between copper oxide and sulfuric acid produces copper sulfate and water in a neutralization reaction.
Excess copper oxide ensures complete neutralization of the acid and a full reaction, leaving some unreacted copper oxide visible after the reaction.
Fluted filter paper is used to separate the copper sulfate from unreacted copper oxide, with the copper oxide acting as residue since it is insoluble.
Anti-bumping granules are added to ensure smooth boiling during evaporation, preventing rapid or uneven boiling.
The solution should be heated gently for two minutes, avoiding any spitting or popping noises, and never allowed to boil dry.
Crystals of copper sulfate can be formed by pouring the solution into an evaporating dish and letting it cool slowly.
Using a wooden spill inside the evaporating dish can speed up crystal formation by providing a rough surface.
Copper sulfate crystals can be hazardous, so it's important not to take them home despite their appealing appearance.
The experiment provides an excellent opportunity for students to practice making other soluble salts, such as copper chloride or zinc sulfate.
Safety precautions, like using student safety sheets and performing risk assessments, are emphasized throughout the process to ensure a safe and successful experiment.
Transcripts
The product we all instantly recognise and know as salt is sodium chloride. Sodium
chloride is the source of sodium, a key nutrient in our diet. Throughout history,
humans have been using salt to preserve meat, clean wounds and make soap.
In chemistry, the term salt refers to a group of ionic compounds
formed by the neutralisation of an acid by a base. Sodium chloride is just one example
of a salt. Today I'm going to be preparing a different soluble salt: copper sulfate.
The name of the salt has two parts: the first part of the name comes from the metal,
metal oxide or metal carbonate; the last part of the name
comes from the acid. This is a very rewarding practical - especially if you get well-formed
crystals at the end - this would explain why this is such a popular experiment.
On first appearance, preparing a soluble crystal in the lab is a straightforward practical. After
all, all you need to do is follow a method. However, every year a high number of incidents
and accidents are reported. Here I'm going to show you how to prepare some copper sulfate crystals.
I'm going to point out where things could potentially go wrong
and where we're going to be using a safer method than the standard one seen in the textbooks.
But don't worry, we're going to follow all the same steps, just in a safer way.
First things first, eye protection on! I'm now going to measure out 15 centimetres-cubed
of sulfuric acid using a measuring cylinder and pour it into a boiling tube.
Next, I'm going to half fill this beaker with hot water for my ready-boiled kettle.
Now, I will gently stand the boiling tube in the hot water for about two to three minutes.
While I wait, I will prepare the base. I need to measure out between 1.8 and 2 g of
black copper oxide powder using a measuring boat. Now add half of the copper oxide to the acid...
agitate gently...
then place the boiling tube back in the water. This method of heating the
sulfuric acid is safer than heating it on a bunsen burner, because it minimises the risk,
of both knocking over hot sulfuric acid when adding the copper oxide,
and the very hot sulfuric acid spilling over the beaker when the copper oxide is added, due to a
rapid reaction taking place. When the reaction subsides add the rest of the copper oxide.
You'll notice that some of the black copper oxide powder remains. Let's take a moment to
think about what has happened here. Remember a salt has formed by the neutralisation of an acid
by a base. Copper oxide has reacted with sulfuric acid to form copper sulfate and water. This is a
neutralisation reaction because the negative sulfate ions have reacted with the positive
copper ions to form copper sulfate and water. We added an excess of copper oxide to ensure
that the reaction has completed and that all of the acid has been neutralised.
In this next step, we're going to separate the product (copper sulfate)
from the unreacted reactant (copper oxide) using filtration. We will be using fluted
filter paper. To do this we will start by folding some filter paper in half...
opening it up and folding it in half again...
opening it up, half again...
and once more in half again.
We will then start making indents between these segments.
Here is one I made earlier!
I have already placed a filter funnel in a 100 centimetre-cubed conical flask
and I will place my fluted filter paper into my funnel.
Now I'm going to pour my copper sulfate into the filter paper.
Be careful when pouring that none of the copper sulfate solution goes over the edge.
The copper sulfate solution is now dripping through the filter paper, down the filter
funnel into the conical flask. And inside the filter paper we can see some black copper oxide.
The copper oxide is insoluble so cannot go through the filter paper: this is called the residue.
Now we need to remove excess water by evaporation to make a concentrated solution of copper sulfate.
Before we start, I need to add two to three anti-bumping granules.
These will help maintain a smooth boiling action
but do not react with any of the particles in the flask.
Now, I'm going to place my conical flask on my tripod
and turn the bunsen burner to the blue roaring flame.
It's important that you let this gently simmer for two minutes only. If you hear any spitting
or popping noises you must turn the heat off immediately and never let the solution boil dry.
I'm going to use a heatproof glove to pour the hot solution into the evaporating dish or petri dish.
Pour it carefully.
If the crystals don't form quickly we can use a wooden spill
and place it inside the evaporating basin. This will speed up the reaction
as it creates a rough surface for the crystals to form on.
As you can see, we have produced some amazing copper sulfate crystals.
If you leave them to cool slowly overnight you could even end up with crystals
that look like this. It might be tempting to take them home
but it's important that you don't because they do carry three hazard warning symbols.
Now that you know how to make copper sulfate crystals, starting with an insoluble oxide,
why not use the same sequence of steps to make other soluble salts? You will need to
start by working out which reactants to use and don't forget to use the student safety
sheets to make a risk assessment before you start. Why not use the additional resources
attached to this video to design a plan to make copper chloride or zinc sulfate crystals?
Thank you for watching, have fun with your experiments!
Inspiring your teaching and learning.
تصفح المزيد من مقاطع الفيديو ذات الصلة
5.0 / 5 (0 votes)