If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Washing soda

Let's see how is washing soda formed and what are its uses.

Want to join the conversation?

  • scuttlebug green style avatar for user Uma
    Why do we need NH4 while creating baking soda? if we don't add that, we might still get HCl.
    (3 votes)
    Default Khan Academy avatar avatar for user
  • aqualine ultimate style avatar for user Aryan Metha
    At , how does the water turn into crystals
    (1 vote)
    Default Khan Academy avatar avatar for user
    • starky seed style avatar for user Dishita
      hey hey hey,
      Let's clear this up,
      during crystallization, water does not turn into crystals
      (layman's terms- a substance which has a definite geometric structure and color)
      rather the anhydrous (water molecules-M.I.A) form of the salt which is generally powdery (amorphous) and soft transform into rigid solid structures when a specific amount of water is added
      (A.K.A Water of crystallization)
      these crystals are not wet
      (I was amazed at this observation),
      it appears that the specific amt. of water(as per formula unit of the salt) becomes part of the crystalline structure(That is why they express 'crystalline') properties!

      This explanation is how I have understood of the topic in simple terms, if I'm wrong do let me know,
      Hope this helps!
      (3 votes)
  • aqualine tree style avatar for user Faiza
    Why and how does Na2CO3.10H2O become Na2CO3.H2O
    (2 votes)
    Default Khan Academy avatar avatar for user
  • blobby green style avatar for user ARYAN WAGLE
    I have a couple of questions:

    1. Is washing soda more effective in removing stains from clothes, than bleaching powder?

    2. How does washing soda help in creating soft glass?
    (1 vote)
    Default Khan Academy avatar avatar for user
    • starky tree style avatar for user kaede
      1. It really depends on the type of stains you want to remove, if its a heavy duty washing stain or grease then washing soda is better but if its any other than bleach is better!

      2. . By adding soda (sodium carbonate), the melting point of the sand is reduced so it can be transformed into glass at lower temperatures. However, adding soda to the mixture reduces its chemical durability, making it prone to dissolve when in contact with liquids. For most applications, that’s not desirable, so limestone (calcium carbonate) is also added to the mixture, which acts as a stabilizer. Once the mixture of silica, soda, and limestone is heated, it can be cooled and molded for a variety of applications.
      (1 vote)
  • piceratops tree style avatar for user Mukund kumar
    If Question come Like write how to make washing soda So do we have to learn and write these 3steps or Just the Last Step Which is OF baking soda
    (1 vote)
    Default Khan Academy avatar avatar for user
  • blobby green style avatar for user laxmisikarwar083
    How washing soda make?please make me understand.
    (0 votes)
    Default Khan Academy avatar avatar for user
    • aqualine ultimate style avatar for user Aryan Metha
      In the following three steps, washing soda is prepared from sodium chloride or common salt.

      Firstly, a cold and concentrated sodium chloride solution is reacted with ammonia and carbon dioxide to obtain sodium hydrogen carbonate.
      The sodium hydrogen carbonate is slightly soluble in water, so it precipitates out as solid.

      NaCl +NH3 +CO2 +H2O → NaHCO3 +NH4Cl

      Secondly, now sodium hydrogen carbonate is separated by filtration, dried and heated. On heating sodium hydrogen carbonate decomposes to form sodium carbonate. This anhydrous sodium carbonate is known as soda ash.

      2NaHCO3 → Na2CO3 +H2O +CO2
      Soda ash
      The preparation of Sodium Carbonate is also known as Solvay process. But before that calcium carbonate (limestone) was heated to release carbon dioxide.

      Thirdly, anhydrous sodium carbonate or soda ash is dissolved in water and recrystallized to get washing soda crystals containing 10 molecules of water of crystallization.

      Na2CO3 + 10H2O → Na2CO3.10H2O

      (2 votes)
  • leaf blue style avatar for user Hasin Punno
    at , How sodium carbonate removes stain ?
    again, how does sodium carbonate combine with MgCO3 and CaCO3 ? is there any common ion effect?
    (0 votes)
    Default Khan Academy avatar avatar for user

Video transcript

- [Instructor] Let's talk about washing soda. You might have seen this white powder in your house. We use this to clean our clothes and remove dirty stains. And if you specifically do not have this powder then you might be using some detergent or washing soap. Which are made of our washing soda. So let's see what exactly is washing soda and how is it made and what are its uses. So washing soda it is chemically known as sodium carbonate deca hydrate. Let's write out it's chemical formula. See sodium carbonate is Na2Co3 carbonate. And deca, this means 10. And hydrate, this stands for water. So 10H2O. So NaCo3 dot 10H2O this is the chemical formula washing soda. And this 10H2O this refers to water of crystallization and don't worry if you haven't studied about this yet, we will talk about water of crystallization in a great detail in a separate video. So for now, the formula of washing soda is Na2Co3 10H2o. Now let's see how to make it. So technically speaking if you have sodium carbonate or Na2Co3 and you add 10 molecules of H2o to it so you should get your washing soda. Right? But you might be wondering how do I get Na2Co3, so for this we use baking soda. We take the help of baking soda. The formula of baking soda is NaHCO3. Sodium hydrogen carbonate. And you know when we heat it, it decomposes to give us Na2Co3. Let's heat it and the equation would look something like this. When you heat it, it decomposes to give Na2Co3 and H2o and Co2, they are equaled out. So you can use the Na2Co3 from here, add water to it and get your washing soda. So if you don't have washing soda at home but your do have baking soda. Then you know, you can heat this in your microwave and get Na2Co3. And from this you can make your own washing soda. Just be very careful of one thing, there will be a lot of carbon dioxide gas being involved. And inhaling this could be dangerous to us, right. So just be very careful while you're doing this at home. Now one more thing. See the formula of washing soda and baking soda it seems very similar, right? They both have sodium and they both have carbonate also. Its just that baking soda has an extra hydrogen and washing soda is without hydrogen. And also washing soda has extra water in it whereas baking soda doesn't. So you know, when I studied them for the first time I used to get confused between their formulas. Between washing soda and baking soda all the time. So I made up this method. I said washing soda has extra water in it because washing requires water and it does not have hydrogen. Whereas baking soda, it on the other hand does not have water but has hydrogen in it and that's how I used to remember them. Okay, now that we saw how to prepare washing soda from baking soda, I hope you also remember how to make baking soda. We saw that in the video of baking soda, right. See, well here, you can guess the reactants. Like we see over here, sodium in the formula so maybe this is coming from sodium chloride. And we see hydrogen so this could come from water, H2o. And carbon, this can come from carbon dioxide, Co2. So yes, the three reactions are NaCl, water, and carbon dioxide. But there was a fourth reaction also. Which I generally forget and that is ammonia, NH3. So the reactants will be NaCl plus H2o plus Co2 plus ammonia NH3. All of these four will react to give me baking soda. And NH4Cl will be formed. And when this baking soda is heated this will decompose to give me Na2Co3, which will combine with water to give us washing soda. And hopefully with this you can see the importance of NaCl. See NaCl, the common salt that we use in our kitchen does not only give the salty taste to our food but it is also used to prepare amazing compounds. Like baking soda and washing soda. And these compounds have many other important uses. So that's why the common salt NaCl is very important in our everyday life. Now let's look at some common uses of washing soda. So as the name suggests, washing soda, is commonly used for washing purposes. See it can remove some tough stains from your clothes and it can also reduce the hardness of water. See water can sometimes have some minerals dissolved in it like magnesium carbonate or calcium carbonate, or some other minerals. Now these minerals can make it hard for soap to show its cleaning property. Soap would not be able to make foam when mixed in hard water. And that's why it would not be able to clean properly. Now when we mix washing soda in this hard water, the molecules of this washing soda they will attach themselves. They will bind themselves to these minerals. And they will take them out and therefore the soap will be able to make a lot of foam and will be able to clean properly. Now because of these reasons, washing soda is a common ingredient for making washing soaps. Now apart from these washing soda is also used to make glass. It can be mixed with silicon and some other compounds to make soft glass. And also, since washing soda has sodium in it, it can be used as an ingredient to make some sodium compounds. So another use is to make sodium compounds. For example, borax. See borax is also used for cleaning things and it can also be used to kill some insects like ants. So these are the uses of washing soda. Now with this, let's summarize the video. So in this video we saw what is the chemical formula of washing soda and don't forget the water of crystallization in it. We will talk about that in detail in a separate video. And we also saw how to prepare washing soda from the very beginning. From NaCl in fact. NaCl to baking soda to washing soda. Remember all the steps okay. And we also saw many many uses of washing soda. I hope you are able to recall all of these things and in case you forgot any of these, you can go back and watch the video again.