caustic soda added in excess and slowly to the solution of ZnCl2
Answers
Answer:
All of these answers are correct but i havent seen one that helps you in the future to not have to ask questions like this in the first place.
Firstly you have given the question as a word equation so I will always answer with a word equation.
When you have a reaction like this at your level only one of two things is likely to happen when you mix together two chemicals.
They react or they do not react.
Your question explicitly asks what the reaction is, which assumes that a reaction is indeed taking place.
When you have a reaction between two chemicals like this you are likely to end up with two chemicals.
Don't think of the chemicals as a whole, but think about them as words. Chemicals, especially at your level, are cleverly named to give you max information with min words.
Think of zinc chloride as zinc and chloride chemically attached to each other.
Think of sodium hydroxide as sodium and hydroxide chemically attached to each other.
So what happens during a chemical reaction? A lot of people think chemistry is the study of atoms but it is essentially the study of electrons. Chemical bonds are just electrons arranged in particular ways. A chemical reaction normally involves breaking bonds and making new ones. This dance of electrons is chemistry. So let's break the chemical attachments I said before. Now we have
zinc and chloride.
Sodium and hydroxide.
How can we put them back together? We k ow that the atoms in our products must match the atoms in our starting chemicals. Atoms can not simply appear and disappear at will.
The most obvious way we can put them back together is to bond the zinc to chloride and the sodium to the hydroxide… but that's what we started with! We know a reaction happens so this isn't the answer.
We have two further options left to us.
The first is:
Zinc sodium and hydroxide chloride
That just doesn't sound right does it? We can't have two “-ides” together because of what “ide” means. It means that we have a negatively charged species. We can't bring two negatively charged species together and expect them to be happy. A central tenant of science is that opposite charges attract and the same ones repel each other. But let's park this possibility for now. Who knows, maybe you don't feel confident enough with chemistry to say that chloride hydroxide isn't a real thing.
Lets try the last option.
Zinc hydroxide and sodium chloride.
Aha! Even the least confident chemistry student should recognise sodium chloride! In fact, if you can make a salt (any salt) then you are laughing all the way to the bank.* Simple salts are incredibly happy chappies who will stick together and force the other chemicals to make do with whoever is left. The most common salts at your level involve a group 1 metal and a halide. Have a look at your periodic table to get a better idea but they are normally one of lithium, sodium or potassium with one of fluorine, chlorine or bromine.
So there is the answer! The reaction makes zinc hydroxide and sodium chloride.
Hopefully now you understand the method a bit more and if I asked you what the reaction was between mercury bromide and potassium hydroxide you could tell me pretty quickly what the answer was.
Have a good day!
*The same goes for water. If you can make water, usually with a hydrogen and a hydroxide then stick them together and see what is left.