Chemistry Compounds

Questions and Answers

What does a chemical formula denote?

The number of atoms of each element present in a compound

How many atoms of nitrogen are present in Lead Nitrate?

What is the symbol for calcium?

What is the valency of sulphur in Iron (III) Sulphate?

3 Signup and view all the answers

Which of the following symbols represents the phosphate radical?

PO43- Signup and view all the answers

How many atoms of oxygen are present in water?

1 Signup and view all the answers

Which of the following is an example of a mixture of two elements?

Iron & sulphur Signup and view all the answers

What is the valency of chlorine?

1 Signup and view all the answers

What element is represented by the symbol 'O'?

Oxygen Signup and view all the answers

What is the correct chemical formula for aluminum phosphate?

Al2(PO4)3 Signup and view all the answers

Which of the following mixtures is commonly found in daily life?

Air Signup and view all the answers

How many atoms of oxygen are in Iron (III) Sulphate?

12 Signup and view all the answers

What percentage of oxygen is present in air as mentioned in the content?

21% Signup and view all the answers

What is the chemical formula for zinc hydroxide?

Zn(OH)2 Signup and view all the answers

Which is the correct formula for magnesium oxide?

MgO Signup and view all the answers

Which of these substances is a mixture of elements and a compound?

Charcoal, sulfur, and potassium nitrate Signup and view all the answers

Which of these elements has a positive valency?

Iron Signup and view all the answers

Determine the correct formula for calcium nitrate.

Ca(NO3)2 Signup and view all the answers

Which of the following is NOT a mixture?

Water Signup and view all the answers

How can the components of a mixture generally be separated?

By simple mechanical or physical means Signup and view all the answers

What is the chemical formula for potassium bromide?

KBr Signup and view all the answers

Identify the chemical formula for sodium carbonate.

Na2CO3 Signup and view all the answers

Which of the following is an example of a homogeneous mixture?

Air Signup and view all the answers

What distinguishes a heterogeneous mixture from a homogeneous mixture?

Heterogeneous mixtures have different compositions and properties throughout. Signup and view all the answers

Which mixture can be classified as a solid-liquid mixture?

Chuck and water Signup and view all the answers

Which of the following is NOT an example of a solid-solid mixture?

Sugar dissolved in water Signup and view all the answers

Which example is an incorrect pairing of a mixture type?

Heterogeneous mixture: sugar dissolved in water Signup and view all the answers

What type of mixture is formed when charcoal is added to water?

Solid-Liquid mixture Signup and view all the answers

Which of the following is a property of compounds?

Compounds have a definite set of properties. Signup and view all the answers

How can components in a mixture be separated?

By physical methods only Signup and view all the answers

Which of the following examples is a mixture?

Air Signup and view all the answers

What defines an element as opposed to a compound?

An element is made up of one kind of atom only. Signup and view all the answers

Which statement about elements is correct?

Elements retain their own properties. Signup and view all the answers

Which of the following substances is a compound?

Iron sulphide Signup and view all the answers

Which of the following statements is true about compounds?

Compounds contain two or more kinds of atoms. Signup and view all the answers

What is a characteristic feature that distinguishes a compound from an element?

A compound has a characteristic melting and boiling point. Signup and view all the answers

Which of the following is NOT true about the properties of compounds?

The elements within compounds retain their original properties. Signup and view all the answers

Which elements combine to form the compound carbon dioxide (CO₂)?

Carbon and Oxygen Signup and view all the answers

How can elements in a compound be separated?

By chemical means only Signup and view all the answers

Which of the following is an example of a compound?

Water (H₂O) Signup and view all the answers

Which property is NOT a characteristic of compounds?

They retain the properties of their constituent elements. Signup and view all the answers

Which statement correctly compares an element and a compound?

An element contains only one kind of atom, while a compound contains two or more kinds of atoms. Signup and view all the answers

Which technique is used to separate a mixture by heating it so that a sublimable solid turns to vapour?

Sublimation Signup and view all the answers

In which technique does the lighter liquid stay in the separating funnel while the heavier liquid is removed from below?

Separating Funnel Signup and view all the answers

Which of these substances is an example of a non-sublimable solid?

Sodium chloride Signup and view all the answers

In the method of distillation, what remains in the flask after heating?

Soluble impurities Signup and view all the answers

What is collected in the receiver during fractional distillation?

Lower boiling point liquid Signup and view all the answers

Which solid, when mixed with water, can be separated using evaporation?

Sodium chloride Signup and view all the answers

Which separation technique involves solid constituents being adsorbed on an absorbent?

Chromatography Signup and view all the answers

Which method would be most suitable for separating alcohol and water?

Fractional Distillation Signup and view all the answers

What is the principle behind the separation of solid-solid mixtures by sublimation?

Difference in sublimable and non-sublimable nature of solids Signup and view all the answers

What happens to sublimable solids when they are heated?

They turn into vapor Signup and view all the answers

Which substance remains behind in the container during the sublimation process?

Non-sublimable solid Signup and view all the answers

Sodium chloride (NaCl) can be separated from ammonium chloride (NH4Cl) using sublimation because:

Ammonium chloride is sublimable while sodium chloride is not Signup and view all the answers

Which of the following is an example of a sublimable substance?

Iodine Signup and view all the answers

During the sublimation process, where is the sublimable solid collected after condensing?

On the inner side of the funnel Signup and view all the answers

In the example given, what is the purpose of the cotton plug in the funnel during the sublimation process?

To prevent vapors from escaping Signup and view all the answers

Which of the following pairs can be separated by sublimation?

Ammonium chloride and sand Signup and view all the answers

What is the process of converting a liquid into a vapour and back into a liquid?

Distillation Signup and view all the answers

Which impurity is left behind in the distillation flask when distilling impure water?

Solid impurities Signup and view all the answers

Which method is used to separate pure water from impure water?

Distillation Signup and view all the answers

Which one of the following is an example of a soluble solid-liquid mixture separated by distillation?

Potassium chloride and water Signup and view all the answers

In the distillation process, where is the vaporized liquid collected?

Receiver Signup and view all the answers

Which compound is paired correctly with water in the technique of distillation?

Lead nitrate Signup and view all the answers

What is the main principle behind the evaporation method for separating a soluble solid-liquid mixture?

Evaporation of the liquid component Signup and view all the answers

Which apparatus is commonly used for smoother steady heating in the evaporation method?

Sand bath Signup and view all the answers

What happens to the liquid component in the evaporation method?

It is lost to the atmosphere Signup and view all the answers

Which of the following is an example of a separation that can be achieved by evaporation?

Common salt (sodium chloride) and water Signup and view all the answers

Which of the following pairs is similar to the example of salt and water separation by evaporation?

Potassium nitrate and water Signup and view all the answers

What is the role of the porcelain crucible in the evaporation method?

To provide a container for heating the mixture Signup and view all the answers

Study Notes

Here are the study notes for the provided text:

Compounds

A compound is a pure substance made up of two or more elements combined chemically in a fixed proportion.
Elements in a compound always retain their original properties.
Compounds can be broken down into elements by chemical means.
Examples of compounds include carbon dioxide (CO2), water (H2O), and lead nitrate (Pb(NO3)2).

Characteristics of Compounds

Compounds are pure substances.
Compounds are always homogeneous, meaning they have a uniform composition.
Compounds have a definite set of properties.
Compounds have a characteristic melting and boiling point.

Comparison of Elements and Compounds

Elements are made up of one kind of atom, whereas compounds are made up of two or more kinds of atoms.
Elements cannot be broken down into simpler substances by physical or chemical means, whereas compounds can be broken down into elements by chemical means.
Properties of compounds differ from those of their elements.

Formula of a Compound

A formula of a compound denotes the number of atoms of each element present in the compound.
The formula of a compound states the types of elements present in the compound and the number of elements present.
Examples of formulas include H2O (water), Pb(NO3)2 (lead nitrate), and Fe2(SO4)3 (iron(III) sulphate).

Writing a Chemical Formula

To write a chemical formula, the symbols and valencies of the elements or radicals must be known.
Valency is the number of hydrogen atoms that can combine with or displace one atom of the element or radical.
The method of writing a chemical formula involves writing the symbols of the elements or radicals with their valencies, interchanging the valencies, and writing the interchanged numbers.

Types of Mixtures

Mixtures are divided into two categories: homogeneous and heterogeneous.
Homogeneous mixtures have the same composition and properties throughout the mixture, and components are uniformly mixed.
Heterogeneous mixtures have different compositions and properties throughout the mixture, and components are not uniformly mixed.
Examples of homogeneous mixtures include salt dissolved in water and air, while examples of heterogeneous mixtures include sand and sugar, and kerosene and water.

Separation of Mixtures

Techniques of separation of mixtures include sublimation, evaporation, distillation, and chromatography.
Sublimation is the process of converting a solid directly into vapor and back to solid without passing through the liquid state.
Evaporation is the process of converting a liquid into a vapor by heating, and back into the liquid.
Distillation is the process of converting a liquid into a vapor by heating, and back into the liquid.
Chromatography is a technique of separating the solid constituents in a liquid constituent.

Separation of Mixtures by Sublimation

Sublimation is used to separate a sublimable solid from a non-sublimable solid.
Sublimable solids turn directly into vapor on heating and back to pure solid on cooling the vapor.
Non-sublimable solids in the mixture remain behind.

Separation of Mixtures by Evaporation

Evaporation is used to separate a soluble solid from its liquid component.
The liquid component evaporates, and the soluble solid remains behind.
Examples of separation by evaporation include separating salt from water and sugar from water.

Separation of Mixtures by Distillation

Distillation is used to separate a liquid from a soluble solid or pure liquid from impure liquid.
The liquid component vaporizes, and the solid or solid impurities remain behind.
Examples of separation by distillation include separating pure water from impure water and lead nitrate from water.

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Description

Learn about the definition and characteristics of compounds, including their composition and properties. Understand how elements combine to form compounds and their chemical breakdown.