Double Displacement Reactions

Summary

This educational video script details a chemistry experiment exploring double displacement reactions. Six test tubes with salt water (sodium chloride) are exposed to various reactants, including calcium hydroxide, copper sulfate, hydrochloric acid, sodium hydroxide, calcium chloride, and potassium chloride. The reactions are observed for signs of precipitate, color change, or gas release. The script explains why certain reactions occur, such as the formation of insoluble calcium sulfate from copper sulfate and calcium hydroxide, and the neutralization reaction between hydrochloric acid and sodium hydroxide, forming water and salt. The experiment highlights the conditions necessary for a double displacement reaction to take place.

Takeaways

• 🧪 The experiment involves testing double displacement reactions between salt water and six different compounds.
• 🔬 Salt water, primarily sodium chloride, is mixed with calcium hydroxide, copper sulfate, hydrochloric acid, sodium hydroxide, calcium chloride, and potassium chloride to observe reactions.
• 🌀 No visible reactions were observed initially with the addition of the second reactants to the salt water.
• 📚 Double displacement reactions occur if a gas, solid, or covalent compound like water is formed.
• 🚫 The reactions with calcium hydroxide and sodium chloride did not proceed because both resulting compounds, calcium chloride and sodium hydroxide, are soluble in water.
• 🌈 Copper sulfate and sodium hydroxide reacted to form copper hydroxide precipitate and sodium sulfate, with the former being insoluble.
• 💧 Hydrochloric acid and calcium hydroxide reacted to form water and calcium chloride, with the former being a covalent compound indicating a reaction.
• 🤔 The lack of visible reaction with sodium hydroxide and hydrochloric acid was confirmed using phenolphthalein as an indicator, revealing a neutralization reaction.
• 🧩 The experiment demonstrates the concept of solubility and reactivity in chemical reactions, showing that not all compounds will react with each other.
• 📉 Calcium chloride reacted with sodium hydroxide to form calcium hydroxide precipitate, indicating a successful double displacement reaction.
• 🔄 The experiment concludes that reactions occurred with copper sulfate and hydrochloric acid, but not with sodium, calcium, or potassium chloride due to the lack of formation of a precipitate, gas, or covalent compound.

Q & A

What is the purpose of adding different reactants to the test tubes containing salt water?

The purpose is to check for a double displacement reaction among the reactants and salt water.

Which reactants were added to the test tubes containing salt water?

Calcium hydroxide, copper sulfate, hydrochloric acid, sodium hydroxide, calcium chloride, and potassium chloride were added.

What was observed in the test tubes after adding the reactants to the salt water?

No color change, no bubbles indicating gas, and no precipitate at the bottom were observed, suggesting no reaction occurred.

Why did the reaction between sodium chloride and calcium hydroxide not proceed?

The potential products, calcium chloride and sodium hydroxide, are both water-soluble, providing no reason for the reaction to proceed.

What conditions are necessary for a double displacement reaction to occur?

A double displacement reaction will occur if a gas is formed, a solid precipitate is formed, or a covalent compound like water is formed.

What happened when copper sulfate was added to the test tubes containing calcium hydroxide?

A reaction occurred, forming a precipitate of calcium sulfate, which is insoluble in water.

What was the observed reaction when hydrochloric acid was added to calcium hydroxide?

A reaction occurred, forming calcium chloride, which is water-soluble, and water, a covalent compound.

What is the significance of the reaction between copper sulfate and sodium hydroxide?

The reaction forms copper hydroxide, which is insoluble and forms a precipitate, and sodium sulfate.

Why was there no visible reaction when hydrochloric acid was added to sodium hydroxide?

The reaction between hydrochloric acid and sodium hydroxide is a neutralization reaction forming water and sodium chloride, which may not be visibly obvious without an indicator.

How was the neutralization reaction between hydrochloric acid and sodium hydroxide confirmed?

The reaction was confirmed by using phenolphthalein as an indicator, which turned the solution pink in the presence of the base, sodium hydroxide.

What was the observed reaction when calcium chloride was added to sodium hydroxide?

A reaction occurred, forming a precipitate of calcium hydroxide, which is insoluble in water.

Why did the addition of potassium chloride to sodium hydroxide not result in a reaction?

Both potassium chloride and sodium hydroxide are chlorides, so there is no reason for the chloride ions to switch and no reaction occurs.

Outlines

00:00

🧪 Double Displacement Reactions with Salt Water

This paragraph describes an experiment involving six test tubes filled with salt water to which various reactants are added to test for double displacement reactions. The reactants include calcium hydroxide, copper sulfate, hydrochloric acid, sodium hydroxide, calcium chloride, and potassium chloride. The experiment shows no visible reaction, indicating that none of these substances react with salt water under the conditions provided. The explanation provided is that a double displacement reaction requires the formation of a gas, solid, or covalent compound like water, which did not occur in these cases.

05:03

🔬 Reaction Series with Calcium Hydroxide and Copper Sulfate

In this section, the experimenter adds different reactants to test tubes containing calcium hydroxide and copper sulfate. The addition of copper sulfate to calcium hydroxide results in the formation of calcium sulfate, which is insoluble and forms a 'snotty' precipitate. Hydrochloric acid reacts with calcium hydroxide to form calcium chloride and water, which is a covalent compound, indicating a neutralization reaction. Other reactants like sodium hydroxide, calcium chloride, and potassium chloride show no visible reaction, suggesting that no double displacement occurred due to the lack of formation of a precipitate, gas, or covalent compound.

10:11

🌀 Copper Sulfate Activity Series and Reaction Observations

The paragraph details the reactions of copper sulfate with various substances, including hydrochloric acid, sodium hydroxide, calcium chloride, and potassium chloride. Sodium hydroxide reacts with copper sulfate to form copper hydroxide precipitate and sodium sulfate. Calcium chloride also shows a reaction with copper sulfate, forming a precipitate. However, hydrochloric acid and potassium chloride do not show an immediate reaction. The use of phenolphthalein as an indicator confirms the neutralization reaction between sodium hydroxide and hydrochloric acid, despite the lack of visible change.

15:13

📉 Hydrochloric Acid and Sodium Hydroxide Neutralization

This paragraph focuses on the neutralization reaction between hydrochloric acid and sodium hydroxide, which results in the formation of water and sodium chloride. The experiment shows that calcium chloride reacts with sodium hydroxide to form calcium hydroxide precipitate. Potassium chloride does not react with sodium hydroxide, as both are already bonded to chlorine, and there is no driving force for a reaction. The use of phenolphthalein as an indicator helps to confirm the occurrence of the neutralization reaction, which was not initially visible.

Keywords

💡Double Displacement Reaction

A double displacement reaction, also known as a metathesis reaction, occurs when two compounds exchange components to form two new compounds. In the context of the video, this concept is central to understanding the experiments being conducted with various reactants in test tubes. For instance, the script describes how sodium chloride (salt water) does not react with other compounds because the resulting products would be soluble, hence no double displacement reaction occurs.

💡Reactants

Reactants are the initial substances that are combined in a chemical reaction. The video script mentions several reactants, such as calcium hydroxide, copper sulfate, and hydrochloric acid, which are added to test tubes containing salt water to observe potential reactions. The reactants are crucial to the experiments' outcomes and the demonstration of chemical principles.

💡Precipitate

A precipitate is a solid that forms in a solution when a solute becomes undissolved due to a chemical reaction. In the video, the script describes the formation of a precipitate when copper sulfate reacts with calcium hydroxide, resulting in calcium sulfate, which is insoluble and thus forms a visible solid in the test tube.

💡Soluble

Solubility refers to the ability of a substance to dissolve in a solvent. The script discusses the solubility of various compounds, such as calcium chloride and sodium hydroxide, which are both soluble in water. This property is important in determining whether a double displacement reaction will occur, as reactions are more likely when an insoluble product is formed.

💡Covalent Compound

A covalent compound is formed when two or more non-metal atoms share electrons. The video script explains that a double displacement reaction is likely to occur if a covalent compound, such as water, is formed. For example, the reaction between hydrochloric acid and calcium hydroxide produces water and calcium chloride, indicating a reaction has taken place.

💡Indicator

An indicator is a substance that changes color in response to changes in pH, helping to identify whether a reaction has occurred. In the script, phenolphthalein is used as an indicator to confirm the neutralization reaction between hydrochloric acid and sodium hydroxide, as it turns pink in basic conditions.

💡Neutralization Reaction

A neutralization reaction is a chemical reaction in which an acid and a base react to form a salt and water. The video describes this type of reaction occurring between hydrochloric acid and sodium hydroxide, resulting in the formation of sodium chloride and water, which is evidenced by the change in color of the phenolphthalein indicator.

💡Insoluble

Insoluble substances do not dissolve well in a given solvent. The script mentions calcium hydroxide as being insoluble in water, which is why it settles at the bottom of the beaker. The concept of insolubility is important for understanding which substances will form precipitates in a reaction.

💡Sodium Chloride

Sodium chloride, commonly known as table salt, is a compound consisting of sodium and chlorine. In the video, sodium chloride is used as the base substance in the test tubes. The script discusses how it does not react with certain other compounds because the potential products would also be soluble, thus not meeting the criteria for a double displacement reaction.

💡Activity Series

The activity series is a list of metals arranged in order of their reactivity. While not explicitly mentioned in the script, the concept is implied in the reactions observed, such as the reaction between copper sulfate and calcium hydroxide, where the calcium displaces the copper to form calcium sulfate. Understanding the activity series helps predict which metals will react with certain compounds.

Highlights

Experiment begins with six test tubes containing salt water and various reactants to check for double displacement reactions.

No visible reaction observed with the addition of calcium hydroxide, copper sulfate, hydrochloric acid, sodium hydroxide, calcium chloride, and potassium chloride to salt water.

Explanation of why no reaction occurred with sodium chloride and the six compounds based on solubility and the criteria for double displacement reactions.

Copper sulfate and calcium hydroxide reaction produces a precipitate, indicating a reaction between the two.

Hydrochloric acid reacts with copper sulfate, forming a precipitate almost immediately, unlike other reactants.

Sodium hydroxide and hydrochloric acid predicted to react in a neutralization reaction, forming water and sodium chloride.

Use of phenolphthalein as an indicator to confirm the neutralization reaction between sodium hydroxide and hydrochloric acid.

Observation of a precipitate forming in the reaction between copper sulfate and sodium hydroxide, indicating the formation of copper hydroxide.

No visible reaction with calcium chloride and copper sulfate initially, but a precipitate is later observed.

No reaction observed between hydrochloric acid and either calcium chloride or potassium chloride due to the lack of driving force.

Demonstration of the difficulty in observing reactions with insoluble calcium hydroxide in water.

Calcium hydroxide and copper sulfate reaction results in calcium sulfate, an insoluble compound that forms a distinct texture.

The importance of covalent compound formation, such as water, in driving double displacement reactions.

No reactions observed with sodium hydroxide, calcium chloride, and potassium chloride in the activity series.

Reaction between sodium hydroxide and calcium chloride, resulting in the formation of calcium hydroxide precipitate.

Final observation of no reaction between calcium chloride and potassium chloride due to both being chlorides.

Summary of the chemical reactions and the conditions necessary for them to occur, emphasizing the role of solubility and the formation of covalent compounds.

Transcripts

okay as you can see here we've got our

salt water so we have about somewhere

between two and three mils of salt water

in each of these six test tubes now

going along with our reaction series

we're going to add our second reactant

to each of these test tubes to check for

a double displacement reaction we've got

calcium hydroxide copper sulfate

hydrochloric acid sodium hydroxide

calcium chloride and potassium chloride

those are the six things that we're

gonna add to these test tubes which all

just contain salt water right now

sodium chloride let's begin we'll start

with our calcium hydroxide this is

barely soluble in water most of it is

settled to the bottom of the beaker so

let's sprinkle some of that it next

we'll do our copper sulfate

next our hydrochloric acid

our sodium hydroxide

calcium chloride

and potassium chloride

okay I'm looking at these test tubes

right now and I see no indication of a

reaction no color change no bubbles to

indicate a gas no precipitate at the

bottom so it appears that none of the

salt water has reacted with these other

compounds

all right so here's our saltwater and we

saw that the saltwater didn't react with

any of the six other compounds what I'm

gonna do now is explain why so in our

first speaker over here I'm sorry our

first test-tube

we've got calcium hydroxide in saltwater

so the sodium chloride could react with

the calcium hydroxide but then we'd have

calcium chloride which is water soluble

and sodium hydroxide which is also

soluble so no reason for that reaction

to go again a double displacement

reaction will only occur if a gas is

formed a solid is formed or a covalent

compound is formed such as water so that

first reaction didn't meet any of those

criterion of those criteria so no

reaction second reaction we have copper

sulfate and in salt water that could

form sodium sulfate and also copper

chloride both of those things are water

soluble so no reaction next one we have

sodium chloride and hydrochloric acid

there's no reason for this reaction to

happen right we just be trading chlorine

for chlorine so why bother same thing

over here we have sodium chloride and

sodium hydroxide both of these compounds

have sodium in them

so why would sodium switch with sodium

and when you wouldn't change anything in

the grand scheme of things

same thing with calcium chloride it's

got chloride in it same thing as sodium

chloride so chlorine wouldn't switch

with chlorine doesn't make any sense

wouldn't contribute and finally same

thing with potassium chloride chlorine

chlorine no reason for the reaction to

happen so there are the answers for our

sodium chloride series now we're looking

at our calcium hydroxide reaction series

we've got about two to three milliliters

of calcium hydroxide in each of these

test tubes calcium hydroxide is pretty

much insoluble in water so we basically

have kind of a little bit of cloudiness

in these most of the calcium hydroxide

is settle to the bottom line container

it looks like this

so we're gonna see what we can see here

we're gonna put our copper sulfate in

the first one and then hydrochloric acid

sodium hydroxide calcium chloride and

potassium chloride let's start with our

copper sulfate

hydrochloric acid

sodium hydroxide

calcium chloride

and potassium chloride

okay looking at these don't see much

indication of a reaction except looking

at our copper sulfate here let's see if

we can focus in on that there's some

cloudiness it looks like a precipitate

is forming

see what happens if we add some of our

solid to these

oh yeah if you look at the copper

sulfate it reacts pretty much instantly

it's chunky

kind of an inconsistent texture in there

all the rest of these kind of look like

we expect them to just kind of cloudy

with the possible exception of with the

HCL here with the HCL it precipitated

almost immediately right out to the

bottom so those two seem very different

from the rest so the HCL in the copper

sulfate seem to react right away the

rest of these just kind of look cloudy

and insoluble like copper sulfate

typically does this is the calcium

hydroxide up close calcium hydroxide

that was formed in the reaction between

I'm sorry not calcium hydroxide copper

sulfate that was formed in the reaction

between copper sulfate and calcium

hydroxide it formed this calcium sulfate

kind of snotty looking stuff in there

okay so here are the answers for our

calcium hydroxide activity series this

is kind of a weird one to do because the

calcium hydroxide is already insoluble

in water so it's kind of hard to see any

sort of reaction at all except in the

case of the calcium hydroxide and the

copper sulfate so in this one basically

the calcium in the copper switched place

and we end up with calcium sulfate which

is insoluble which kind of forms this

kind of like almost snot looking stuff

you can see that they're real pretty

with our hydrogen chloride or a

hydrochloric acid you can see a reaction

happen right away - and that it's

settled much faster than all of our

other ones with that particular reaction

what happens is the calcium from the

calcium hydroxide kind of gloms on to

the chlorine from the hydrochloric acid

we end up with calcium chloride which is

water-soluble and the OAH from the

calcium hydroxide gloms onto the

hydrogen from the hydrochloric acid and

we form water so what this does is it

takes a lot of the stuff out of solution

and makes it soluble and basically that

that insoluble stuff is left in the

bottom that's just unreacted calcium so

if we formed soluble compounds why do we

why did this reaction happen well it's

because water was formed as you know

water is a covalent compound and one of

the reasons for a double displacement

reaction to happen is the formation of a

covalent compound so for this activity

series we did not have any reactions

with the three on the right that's the

sodium hydroxide the calcium chloride

and the potassium chloride we did have

reactions with the copper sulfate where

a solid was formed

that's the calcium sulfate and with the

hydrochloric acid where it basically

neutralized to form water hydrochloric

acid you'll learn later is a strong acid

and the calcium hydroxide is a base so

there you go

all right next up we have our copper

sulfate activity series the copper

sulfate to begin with kind of has this

beautiful blue color

let's add our second reactants so we're

going to start with some hydrochloric

acid sodium hydroxide

some calcium chloride

and some potassium chloride

well it looks like right away we have

some reactions

the most obvious of which would be the

sodium hydroxide when the copper sulfate

reacts with the sodium hydroxide we

basically get copper hydroxide and

sodium sulfate and the copper hydroxide

is insoluble so we get this kind of

goopy looking precipitate forming up at

the top and a layer these other three

show no change really they kind of all

look the same

in fact for copper sulfate and calcium

chloride it looks just like water and

for copper sulfate and potassium

chloride again no significant change

here no significant change interesting

all right now we're looking back at our

copper sulfate samples and we can see

pretty clearly now that a reaction has

occurred with the calcium chloride we're

seeing precipitate form and start to

fall to the bottom

we already saw the reaction happen with

the sodium hydroxide we can see a little

better now but clearly that ones happen

as well we still can't see the reaction

with the hydrochloric acid we'll have to

use some sort of indicator to suss that

out okay now it's time for our

hydrochloric acid tests we got some HCL

in there so in there and

some in there so the first one we're

gonna add sodium hydroxide we predict

your reaction here so do my Drock sides

and base doesn't look like anything's

going on let's add our calcium chloride

and our potassium chloride and we see no

visible reaction all right with our

hydrochloric acid we predicted that the

sodium hydroxide would react that the

sodium would leave the hydroxide go to

the chlorine form salt sodium chloride

and we'd also get water covalent

compound but we didn't see any evidence

of that we predicted that these two both

chloride compounds wouldn't react right

because why would chlorine replace

chlorine doesn't make any sense okay

and I actually makes sure if this if

didn't reaction didn't happen let's add

a little bit of indicator so I'm gonna

put in some phenolphthalein

and in all three of these we get kind of

a milky looking solution Fila failing is

an indicator that should turn kind of

bright pink eye in the presence of a

base so let's add some base

you can see as soon as I add the sodium

hydroxide the solution turns pink but

then it quickly turns back to this kind

of milky color let's just keep adding

starting to stay pink let's see if

that's enough to make it stay nope keep

going

and now our solution has a nice rich

pink color let's see if that's true with

these other two keep adding some

chlorine so calcium chloride nope I can

add calcium chloride all day and I won't

get that reaction sans try the same with

potassium chloride nope and nope

okay so adding those two until my

heart's content I don't see the

indicator work with the addition of the

phenolphthalein it most definitely does

work

so there you go this one actually did

have a chemical reaction even though we

couldn't first see it we had to use some

other chemical means to see that

reaction and again with our sodium

hydroxide and our hydrochloric acid this

is called a neutralization reaction

you'll learn about it later basically we

take a base and an acid atom together

and you get mostly water and all water

if you do it perfectly and then some

other sort of compound in this case it's

salt sodium chloride okay there you go

so here we have some hydrochloric acid

we're gonna add some pure sodium

hydroxide and see what happens

okay now we have two test tubes filled

with our sodium hydroxide let's put in

some calcium chloride and some potassium

chloride I don't see any evidence of a

reaction right now but let's give it

some time okay now we can see that no

reaction happened with the potassium

chloride but with the calcium chloride

we have a lot of precipitate formed so

definitely a reaction happened there

with the sodium hydroxide reactions the

reason it reacted with calcium chloride

is because it forms calcium hydroxide

and calcium hydroxide is not soluble in

water so that's why we see this

precipitate form our last reaction is

calcium chloride we're gonna stick some

potassium chloride in there and we see

no reaction right both of them are

chlorides so there's no reason to trade

because they're both already bonded to

chlorine so no reaction