Chemistry Basics Quiz

Questions and Answers

Which of the following can a compound be separated into?

Filtration

Physical means like distillation

Sublimation

Chemical means (correct)

A mixture can be separated into its components only by chemical means.

False

In what ratio do hydrogen and oxygen combine to form water?

2:1

All things we eat are mixtures of a variety of substances like carbohydrates, proteins, vitamins, and __________.

salts Signup and view all the answers

Match the following compounds with their mass ratio:

Water = 1:8 (Hydrogen:Oxygen) Carbon Dioxide = 3:8 (Carbon:Oxygen) Signup and view all the answers

Which of the following is an example of a mixture?

Sea Water Signup and view all the answers

Pure substances are commonly found in nature without any mixing.

False Signup and view all the answers

What is the total mass of products in a chemical reaction equal to?

Total mass of reactants Signup and view all the answers

What is true about the components of a mixture?

They coexist without reacting. Signup and view all the answers

All mixtures are homogeneous and cannot be easily separated.

False Signup and view all the answers

Name a method that can be used to separate sand from salt.

Filtration Signup and view all the answers

A mixture of salt and pepper is an example of a __________ mixture.

heterogeneous Signup and view all the answers

Match the following types of mixtures with their examples:

Solid mixture = Salt and sand Liquid mixture = Oil and water Gaseous mixture = Air Solid-liquid mixture = Mud Signup and view all the answers

Which of the following statements about homogeneous mixtures is correct?

They have the same properties and composition throughout. Signup and view all the answers

The components of a mixture retain their individual properties.

True Signup and view all the answers

What is one common substance obtained from separating a mixture?

Petrol Signup and view all the answers

Which property is true for compounds?

Have a fixed mass ratio of elements. Signup and view all the answers

A molecule of ozone consists of three oxygen atoms.

True Signup and view all the answers

What is the formula that represents water?

H₂O Signup and view all the answers

The elements in a compound can only be separated by ______ means.

chemical Signup and view all the answers

Match the compounds with their formulas:

Water = H₂O Carbon dioxide = CO₂ Sulfur dioxide = SO₂ Carbon monoxide = CO Signup and view all the answers

Which of the following is an example of a diatomic molecule?

Hydrogen Signup and view all the answers

The atomicity of sulfur is eight.

True Signup and view all the answers

What does the formula CO₂ represent?

Carbon dioxide Signup and view all the answers

A molecule of ______ consists of two nitrogen atoms.

N₂ Signup and view all the answers

Which element is represented by the formula Cl₂?

Chlorine Signup and view all the answers

Which of the following can be separated by physical means?

Air Signup and view all the answers

The properties of a compound are the same as those of its constituent elements.

False Signup and view all the answers

What is the atomic ratio of hydrogen to oxygen in water?

2:1 Signup and view all the answers

A compound can only be split into its constituent elements by __________ means.

chemical Signup and view all the answers

Match the following compounds with their properties:

Water = Differs from hydrogen and oxygen Carbon dioxide = Differs from carbon and oxygen Hydrogen = Element Oxygen = Element Signup and view all the answers

Which statement about mixtures is true?

Mixtures can be separated by physical means. Signup and view all the answers

Carbon reacts with oxygen in a fixed mass ratio of 3:8 to form carbon dioxide.

True Signup and view all the answers

Give an example of a mixture found in nature.

Air Signup and view all the answers

What is the first step in obtaining common salt from sea water?

Collecting seawater in shallow pits Signup and view all the answers

Crystallisation occurs when sufficient water has evaporated from a concentrated solution.

True Signup and view all the answers

What chemical is mixed with salt to create iodised table salt?

Sodium iodate Signup and view all the answers

The process of removing the solvent from a solution to obtain a solid is called __________.

evaporation Signup and view all the answers

Match the following steps with their correct order in obtaining salt from a salt-sand mixture:

Warm the mixture = Step 1 Filter the mixture = Step 2 Obtain the sand residue = Step 3 Collect the salt solution = Step 4 Signup and view all the answers

Which method is used to separate iron filings from chalk?

Magnetic separation Signup and view all the answers

Evaporation can be used to separate a solid from its liquid solution.

True Signup and view all the answers

Name a type of mixture that involves both a solid and a gas.

Smoke Signup and view all the answers

A mixture of salt and sand can be separated by dissolving salt in water and then __________ the solution.

evaporating Signup and view all the answers

Match the following mixture types with their examples:

Solid = Brass Liquid = Spirit in water Gaseous = Air Solid-liquid = Sand + water Signup and view all the answers

What property is utilized in separating components of mixtures?

Characteristic properties like solubility and melting point Signup and view all the answers

All mixtures can be separated into their components using the same method.

False Signup and view all the answers

What is a common process to obtain drinking water from ordinary water?

Filtration or distillation Signup and view all the answers

Which of the following is a characteristic of a pure substance?

Cannot be split into simpler substances Signup and view all the answers

A compound is a mixture of two or more elements that are chemically bonded together.

True Signup and view all the answers

What is the symbol for Nitrogen?

N Signup and view all the answers

Air is a mixture of elements like ______ and compounds like carbon dioxide.

oxygen Signup and view all the answers

Match the following elements with their symbols:

Oxygen = O Hydrogen = H Carbon = C Boron = B Signup and view all the answers

Which of the following is NOT a pure substance?

Air Signup and view all the answers

A mixture can be separated into its components by physical means.

True Signup and view all the answers

What is an element?

A substance that cannot be split into simpler substances by chemical means. Signup and view all the answers

Which of the following liquids are immiscible?

Oil and water Signup and view all the answers

In sublimation, a solid directly becomes a liquid.

False Signup and view all the answers

What is the function of a separating funnel?

To separate immiscible liquids. Signup and view all the answers

_________ can be separated from sand by sublimation.

Ammonium chloride Signup and view all the answers

Match the separation technique to its description.

Sublimation = Solid to gas directly Chromatography = Separation using a solvent Separating Funnel = Separates immiscible liquids Adsorption = Substance adherence to a surface Signup and view all the answers

What happens when immiscible liquids are mixed and allowed to settle?

They form separate layers. Signup and view all the answers

Chromatography is based on the principle of adsorption.

True Signup and view all the answers

How does the separating funnel work?

By allowing the heavier liquid to be drawn off while keeping the lighter liquid above. Signup and view all the answers

What is the main purpose of filtration in the dissolution process?

To separate the soluble from the insoluble components Signup and view all the answers

In distillation, both the solid and liquid components can be separated effectively.

False Signup and view all the answers

What is the role of the Liebig condenser in the distillation process?

To cool and condense the vapor into liquid Signup and view all the answers

Fractional distillation is used for liquids that differ in their boiling points by at least __________ °C.

20 Signup and view all the answers

Match the separation method with its appropriate application:

Dissolution = Separating soluble from insoluble solids Distillation = Separating liquid from solid Fractional Distillation = Separating liquids with different boiling points Filtration = Removing solid impurities from liquids Signup and view all the answers

What is the first step in the dissolution process of salt and sand?

Add water and stir Signup and view all the answers

The residue obtained after evaporating the filtrate is salt.

True Signup and view all the answers

Describe what happens to the temperature during the fractional distillation of a mixture.

The temperature remains constant while the lower-boiling liquid distills off, then increases for the higher-boiling liquid. Signup and view all the answers

What is the primary purpose of chromatography?

To separate components of a mixture Signup and view all the answers

The adsorbent in chromatography is known as the mobile phase.

False Signup and view all the answers

What is the term used to describe the patterns of colors obtained on the chromatographic paper?

chromatogram Signup and view all the answers

In chromatography, the substance that is adsorbed is called the __________.

adsorbate Signup and view all the answers

Match the following terms with their definitions:

Stationary phase = Substance that forms a layer Mobile phase = Solution that carries the solute Adsorbent = Material that retains the adsorbate Chromatogram = Pattern of separated components Signup and view all the answers

Which substance is NOT typically used as an adsorbent in chromatography?

Copper Signup and view all the answers

The solvent does not play a significant role in the chromatography process.

False Signup and view all the answers

What is one common solvent mixture used in chromatography?

Water-alcohol mixture Signup and view all the answers

Study Notes

Elements, Compounds and Mixtures

Everything is composed of elements, which can chemically combine to form compounds.
Mixtures can be comprised of elements or compounds without any chemical reactions happening between them.

Classification of Substances

Substances are categorized into three groups: Elements, Compounds, and Mixtures.
Pure substances cannot be separated into simpler substances by physical methods.

Elements

An element is a substance that cannot be chemically broken into simpler substances.
Elements are denoted by symbols derived from their English or Latin names (e.g., H for Hydrogen, O for Oxygen).
Elements can have one or two letters in their symbols, such as He for Helium or Al for Aluminium.

Characteristics of Compounds

Compounds can only be separated into their elements by chemical means, not physical ones.
The atomic properties of elements remain, even when they form compounds (e.g., water retains properties of hydrogen and oxygen).
Elements in a compound combine in a fixed mass ratio (e.g., water has a mass ratio of 8:1 for oxygen to hydrogen).

Representation of Compounds

Compounds are represented by chemical formulas indicating the number of atoms of each element (e.g., H₂O for water).
Common compounds include:
- Water (H₂O)
- Carbon Dioxide (CO₂)
- Sulphur Dioxide (SO₂)

Molecules of Elements

Molecules consist of two or more atoms bonded together, capable of independent existence.
Examples of molecular forms include diatomic molecules like H₂ (Hydrogen) and O₂ (Oxygen) and polyatomic molecules like O₃ (Ozone), P₄ (Phosphorus), and S₈ (Sulphur).

Characteristics of Mixtures

Mixtures can be separated into pure components by physical means (e.g., filtration, distillation).
The proportions of components in a mixture can vary, and their properties are retained (e.g., sugar retains sweetness in a sugar-water mixture).

Types of Mixtures

Mixtures can be classified based on the physical state of their components, such as solid mixtures (sand and salt) and liquid mixtures (sugar solution).
Mixtures can be homogeneous (uniform composition, e.g., saltwater) or heterogeneous (distinct composition in different parts, e.g., salad).

Methods of Separation

Separation methods take advantage of the distinct properties of components, including:
- Magnetic Separation: Uses a magnet to attract magnetic components (e.g., iron filings from chalk).
- Evaporation: Removes liquid to leave behind solids (e.g., salt from saltwater).
- Distillation: Separates liquids based on boiling points, collecting vaporized liquid separately.
- Fractional Distillation: Used for liquids with significantly different boiling points.
- Sublimation: Separates substances that can change from solid to vapor without melting.
- Chromatography: Uses solvent to separate components based on their adsorption properties.

Special Techniques for Separation

Separating Funnel: Used to separate immiscible liquids that form distinct layers.
Crystallization: Forms pure crystalline substances from concentrated solutions.
Dissolution and Evaporation: Involves dissolving soluble components and then evaporating the solvent to recover the solute.

Obtaining Common Salt

Common salt is obtained by evaporating sea water, concentrating salt as water evaporates until crystallization occurs.

Logistics of Mixture Separation

Separation methods cater to the specific properties of the components to achieve purity.
Techniques are used to isolate desirable substances and remove contaminants effectively.### Immiscible Liquids
Immiscible liquids do not dissolve in one another, with oil and water being a prime example.
In an experiment, adding colored oils to water creates three distinct layers based on density: oil floats on top due to being lighter, water settles at the bottom.

Chromatography

A separation technique applied when mixture components are soluble in a solvent.
Used to segregate pigments from flowers or inks, relying on the principle of adsorption.
Adsorption involves an adsorbate (substance being adsorbed) coating the surface of an adsorbent (substance capturing the adsorbate).
Common adsorbents include alumina, silica, and cellulose in various forms.
Paper Chromatography: utilizes filter paper or chromatographic paper to separate mixtures.
As a liquid mix is placed on an adsorbent, different components adsorb to varying extents, leading to distinct movement speeds and separation.

Key Terminology

Stationary Phase: The adsorbent substance (e.g., paper) that remains fixed.
Mobile Phase: The solvent solution that moves through the stationary phase.
Chromatogram: The resulting colored bands on the paper after separation.

Activities Demonstrating Chromatography

Create a long strip of filter paper and apply ink to one end.
Hang the paper in water so the ink-soaked end touches the liquid, allowing capillary action to separate colors.
As the solvent rises, different ink colors will emerge, revealing components such as blue and yellow from green ink.

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Description

Test your knowledge on the fundamental concepts of chemistry, including the separation of compounds and mixtures. Explore the composition of water and the mass ratios of various compounds. This quiz will challenge your understanding of chemical properties and mixtures.