Conducting practical experiments is one of the best ways to achieve this – after all, science isn’t just about theory. Here we explain the salt-making process in more detail and provide step-by-step instructions to help you carry out your own salt experiment.
In this post:
Introduction: the chemical applications for salts
Salts have a wide range of applications. As well as being used for culinary purposes such as seasoning and food preservation, they also have a variety of industrial applications. These include manufacturing soaps, fertilisers, and pesticides.
The chemical applications for salts vary depending on the type of salt. For example, nitrate salts are commonly used to make fertilisers and explosives, where they act as oxidising agents.
What is the chemical compound for salt?
Salts are compounds with ionic bonds. They’re generally produced by the neutralisation reaction between an acid and a base. The composition of the compounds varies considerably depending on the type of reactants.
Different types of salts
Salts can be classified based on their structure and composition. For example, salts are classed as hydrated salts if they’re bonded with water molecules in their crystalline lattice structure. However, it’s usually simpler to categorise salts according to the composition of the reactants that formed them.
Chloride salts have a chlorine atom per molecule. They’re generally formed from the reaction between hydrochloric acid and a metal or a basic compound. The most common and familiar example is sodium chloride, or table salt.
Nitrate salts are generally formed from the reaction between nitric acid and a base. One common example of a nitrate salt is sodium nitrate, which is used to manufacture fertilisers. This can be derived through the reaction of nitric acid with sodium carbonate, as shown in the balanced equation below.
2 HNO3 + Na2CO3 → 2 NaNO3 + H2O + CO
Some common examples of sulphate salts include magnesium sulphate, copper sulphate, calcium sulphate dihydrate (gypsum), and sodium sulphate. Generally speaking, sulphate salts can be made through the neutralisation reaction between sulphuric acid and a base.
Learn more about the different types of salt in chemistry and their uses.
Is making salt dangerous?
Making salts through neutralisation can be dangerous because this type of reaction is exothermic. It also involves corrosive substances that are toxic if ingested.
It’s therefore important to take extra precautions and wear the appropriate PPE when making salt in the chemistry laboratory or on the factory floor.
What is the process for making salts?
There are several ways of preparing salt. Some processes, such as the evaporation of salt from seawater, involve physical changes (the chemical composition remains the same but there’s a change to its physical state).
Others involve chemical changes (the chemical bonds break and new ones are formed). Chemical changes include various neutralisation reactions involving different types of acids and bases.
Chemically speaking, salts are compounds that dissociate into positive and negative ions (cations and anions) when dissolved in water. They generally have a metallic and a non-metallic component.
Salts have a zero net charge and the vast majority of them form crystalline structures. One example of a salt that doesn’t have a crystalline structure is tin(II) diphosphate(V): Sn2P2O7.
Here’s a step-by-step experiment you can do to produce a type of salt known as zinc chloride. The balanced equation for this reaction can be written as:
Step 1: Dilute hydrochloric acid
The hydrochloric acid that’s used in laboratories and industry can be as concentrated as 38% or even 40%. At such high concentrations, the acid solution becomes too volatile and would require special containers and facilities to maintain the right temperature and pressure.
For a salt-making experiment such as this, it’s best to dilute the acid to a safe level of around 10%. This helps to reduce the risk by minimising the exothermic rate of reactions.
Step 2: Add powdered zinc carbonate to acid
Prepare powdered zinc carbonate in a beaker. Then, gradually add it to the acid solution. Slowly pour powdered zinc carbonate into the acid solution and observe if some residues are being formed.
Step 3: Continue to add powder until you have an excess amount
Continue adding zinc carbonate into the solution until the reaction is complete. When the bubbles stop and the powder becomes insoluble, the reaction is complete.
Step 4: Filter the mixture in the beaker to remove the excess zinc
Once the reaction is complete, filter the mixture using filter paper and a funnel. Pour the mixture into another beaker while filtering to remove the excess zinc carbonate.
Salts are ionic compounds with zero net charge. They’re generally formed through the neutralisation reaction between an acid and a base. Salts can be classified based on their composition and structure. There are various ways to make salts – some involve physical changes while others involve chemical changes. You can perform a simple experiment using hydrochloric acid and powdered zinc carbonate to make a salt called zinc chloride.
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