In our daily lives, we come across a variety of products labelled as pure. You may have noticed it on the packages of milk, butter, ghee, and so on.
For the average person, anything that is free of adulteration or foreign substances is pure, but this is not true from a scientific perspective. In science, anything made up of only one element is referred to as pure. As a result, even though the carton of milk is labelled as pure, it is not. It is not pure for scientific purposes, but it is considered a mixture.
Definition: A mixture is formed when two or more substances are combined in such a way that each substance retains its own chemical identity. Chemical bonds between the components are not formed or broken. Even if the chemical properties of the components remain unchanged, a mixture may exhibit new physical properties, such as boiling and melting points. For example, combining water and alcohol results in a mixture with a higher boiling point and a lower melting point than alcohol (lower boiling point and higher boiling point than water).
Thus, the components of a mixture do not chemically combine to form a new material. Instead, they simply mix while retaining their original characteristics.
Mixtures Chemistry Questions with Solutions
Q1. Which of the following best describes a chemical mixture?
- A compound made from different elements
- A substance made through chemical bonding
- When two substances are combined but are not chemically bonded
- All of the above
- None of the Above
Correct Answer. (c)
Q2. Which of the following is NOT a property of a mixture?
- The components can be easily separated
- The original properties of the combined substances are changed
- The proportion of the components is variable
- Two or more substances are combined
- All of the Above
Correct Answer. (b)
Q3. Which of the following is an example of a homogeneous mixture?
- Metal alloys
- All of the Above
Correct Answer. (e)
Q4. In what type of mixture are the substances evenly distributed throughout the mixture?
- All types of mixtures
- No types of mixtures
Correct Answer. (a)
Q5. What type of mixture is steel?
Correct Answer. (a)
Q6. State True or False.
Only specific compounds can be combined to form mixtures.
Q7. Define mixture.
Answer. When two or more substances mix without undergoing any chemical change, the resulting substance is referred to as a Mixture in chemistry.
The result of the combination of substances does not lose its uniqueness, nor are they chemically combined. A mixture is the end result of mechanically blending or mixing chemical substances such as elements and compounds.
Q8. Define colloid.
Answer. A colloidal solution appears homogeneous to the naked eye, but particles can be seen under a microscope. The size of the particles ranges from 1 nanometer to 1 micrometre. Colloids, like solutions, are physically stable. They demonstrate the Tyndall effect. Decantation cannot be used to separate colloid components; however, centrifugation can. Hair spray (gas), smoke (gas), whipped cream (liquid foam), and blood are all examples of colloids (liquid).
Q9. Give an example for each of the following:
- Solid-liquid homogeneous mixture
- Gas-gas homogeneous mixture
- Liquid-liquid heterogeneous mixture
- salt in water
- Water and oil
Q10. Write your observation when the following processes take place:
- An aqueous solution of sugar is heated till it gets dried up.
- A saturated solution of KCL at 60° C is allowed to cool at room temperature.
- A mixture of iron filings and sulphur powder is heated strongly.
- A beam of light is passed through a colloidal solution.
- Dilute HCI is added to a mixture of iron filings and sulphur powder.
- When a sugar aqueous solution is heated to dryness, the sugar is left behind in the container after the water vaporises.
- In the liquid solution, we would see crystals of potassium chloride forming.
- There will be the formation of iron sulphide (FeS).
- The light is scattered, and this is known as the Tyndall effect.
- It will separate S and Fe, resulting in the formation of H2S gas and iron chloride (FeCl2)
Q11. Identify the following as homogeneous or heterogeneous matter.
- Iron nail
- Aerosol spray
- Gasoline – homogeneous
- Dirt – heterogeneous
- Smog – heterogeneous
- Alcohol – homogeneous
- Iron nail – heterogeneous
- Vinegar – homogeneous
- Aerosol spray
- Air – homogeneous
- Seawater – heterogeneous
- Steel – homogeneous
Q12. What are some of the common techniques used in separating mixtures?
Answer. Some of the common techniques used in separating mixtures are as follow:
- Separating funnel
- Simple distillation
- Fractional distillation
Q13. What are the properties of mixtures?
Answer. The various properties of mixtures are discussed further below.
- A mixture’s constituents do not exist in a fixed ratio.
- Although there is no chemical force acting between the two or more substances that are mixed, they still coexist.
- They can be either heterogeneous or homogeneous.
- The proportions of the substances vary indefinitely.
- The mixture’s properties are determined by the individual components.
- Physical methods can be used to separate the mixture’s constituents.
- The boiling and melting points of the mixture are determined by the properties of the constituents.
- There is no change in energy during the formation of a mixture.
- Mixtures can be formed by combining all states of matter (solids, liquids, and gases).
Q14. Give the difference between Homogeneous and Heterogeneous mixtures.
Answer. The difference between a Homogeneous mixture and a Heterogeneous mixture is as follows-
It has a uniform composition
It has a non-uniform composition
It has only one phase
There are two or more phases
It can’t be separated out physically
It can be separated out physically
‘homo’ means the same
‘hetero’ means different
Example: a mixture of alcohol and water
Example: a mixture of sodium chloride and sand
Q15. What is the difference between mixture and solution?
Answer. The difference between mixture and solution is s follows-
In a mixture, substances are generally just mixed and are not completely dissolved.
In a solution, substances are dissolved completely and they cannot be filtered out.
The mixture comprises two or three compounds that aren’t fused chemically. They have no physical interactions.
A solution contains two substances that are chemically mixed to form a new compound.
The chemical properties of each substance are retained without change.
Chemical properties usually change.
The amount of substances in a mixture can vary and amounts don’t have a fixed ratio.
A solution usually has a fixed ratio or amount of substances.
Mixtures can be classified primarily into two groups, namely homogeneous mixtures and heterogeneous mixtures.
A solution is a type of homogeneous mixture.
Practise Questions on Mixtures
Q1. A combination of a liquid and a solid in which the solid does not dissolve:
Q2. State the separation technique used for the separation of the following:
- Ammonium chloride from a mixture containing sodium chloride and ammonium chloride
- Copper sulphate from its solution in water.
Q3. List the two conditions essential for using distillation as a method for the separation of the components from a mixture.
Q4. Seawater can be classified as homogeneous as well as a heterogeneous mixture.’ Comment.
Q5. Name the separation technique you would follow to separate
(i) Dyes from black ink.
(ii) A mixture of salt and ammonium chloride
(iii) Cream from milk
(iv) Sodium chloride from its solution in water
Click the PDF to check the answers for Practice Questions.