Chemistry Chapter: Chemical Reactions

Questions and Answers

What is formed when magnesium burns in air?

Magnesium chloride

Magnesium hydroxide

Magnesium oxide (correct)

Magnesium sulfate

In a chemical equation, reactants are written on the right side.

False

What does a catalyst do in a chemical reaction?

A catalyst speeds up the rate of reaction without being consumed in the process.

The process of a chemical reaction is represented by a _____ equation.

chemical Signup and view all the answers

Match the following terms with their definitions:

Reactants = Substances that undergo a chemical change Products = Substances formed from a chemical change Catalyst = Speeds up a reaction without being consumed Chemical Equation = Representation of a chemical reaction Signup and view all the answers

Which of the following represents a chemical reaction?

Carbon + Oxygen --> Carbon Dioxide Signup and view all the answers

Hydrogen peroxide decomposes slower in the presence of manganese dioxide.

False Signup and view all the answers

Provide one example of a word equation.

Hydrogen + Oxygen --> Water Signup and view all the answers

Which of the following indicates a chemical reaction has likely occurred?

Color change Signup and view all the answers

A chemical reaction only involves physical changes in matter.

False Signup and view all the answers

What happens to copper(II) carbonate when it is heated?

It changes color from green to black and carbon dioxide gas is formed. Signup and view all the answers

A new substance is formed during a __________.

chemical reaction Signup and view all the answers

Match the observations with their implications:

Color change = Indicates a chemical reaction Gas evolution = Suggests formation of a new substance Precipitate formation = New solid substance created Heat absorption or release = Involved in the reaction process Signup and view all the answers

Which of the following indicates a chemical change?

Burning of wood Signup and view all the answers

A chemical equation is a graphical representation of a chemical reaction.

False Signup and view all the answers

What is formed when hydrogen reacts with oxygen?

Water ($H_2O$) Signup and view all the answers

A covalent bond is formed when atoms share their ________ electrons.

valence Signup and view all the answers

Match the following chemical substances with their correct chemical formulas:

Water = $H_2O$ Carbon Dioxide = $CO_2$ Oxygen = $O_2$ Hydrogen = $H_2$ Signup and view all the answers

How many covalent bonds can a carbon atom form?

4 Signup and view all the answers

Combustion of fuel is an example of a physical change.

False Signup and view all the answers

What must be done to balance a chemical equation?

Adjust the coefficients in front of each formula. Signup and view all the answers

What gas is evolved when ammonium chloride is heated with dry slaked lime?

Ammonia Signup and view all the answers

Sodium hydroxide is produced when sodium reacts with water.

True Signup and view all the answers

What happens when hydrogen is ignited?

It burns with a pop. Signup and view all the answers

Sodium carbonate reacts with hydrochloric acid to produce sodium chloride, water, and __________.

carbon dioxide Signup and view all the answers

Match the following gases with their characteristic smells:

Ammonia = Pungent smell Hydrogen sulfide = Rotten eggs smell Carbon dioxide = No distinct smell Chlorine = Strong, irritating smell Signup and view all the answers

___ are cell organelles that are involved in protein synthesis.

Ribosomes Signup and view all the answers

Which of the following organelles is responsible for respiration and energy production?

Mitochondria Signup and view all the answers

Humans are made up of prokaryotic cells.

False Signup and view all the answers

Match the following cellular structures with their functions:

Cell membrane = Protective barrier allowing selective transport Chloroplasts = Site of photosynthesis Cell wall = Provides structure and support Mitochondria = Produces energy Signup and view all the answers

What are the functional units of heredity that regulate cellular functions?

Genes Signup and view all the answers

What is formed when ammonia gas reacts with hydrogen chloride gas?

Ammonium Chloride Signup and view all the answers

The reaction of a soluble carbonate with a dilute acid results in the formation of a precipitate.

True Signup and view all the answers

What type of change occurs when a spoonful of sugar is dissolved in water?

Change in state Signup and view all the answers

When a saturated solution of sodium chloride cools, __________ of sodium chloride can be observed.

crystals Signup and view all the answers

Match the following reactions with their products:

Ammonia + Hydrogen chloride = Ammonium chloride Sodium chloride + Water = Crystals of sodium chloride Soluble carbonate + Dilute acid = Calcium carbonate precipitate Saturated solution + Cooling = Sodium chloride crystals Signup and view all the answers

Which of the following metals is known for its high tensile strength?

Copper Signup and view all the answers

Metals are poor conductors of heat and electricity.

False Signup and view all the answers

Name one property that all metals share.

They have a metallic luster. Signup and view all the answers

Iron is commonly used in construction due to its _____ strength.

tensile Signup and view all the answers

Match the following metals with their properties:

Iron = High tensile strength Aluminum = Good conductor of heat Copper = Excellent electrical conductor Gold = Reflective luster Signup and view all the answers

What is likely indicated by the presence of two tables labeled 'Specific Gravity' in the image?

They provide data or values related to specific gravity. Signup and view all the answers

The presence of an image on the page is clearly discernible.

False Signup and view all the answers

What could be the reason for having two tables on a page?

To compare different materials or provide various data on specific gravity. Signup and view all the answers

The two tables labeled Specific Gravity likely contain information about _______.

different substances or materials Signup and view all the answers

Match the following terms with their likely descriptions:

Specific Gravity = A measure of density compared to water Table = A structured arrangement of data Image = A visual representation Textbook = A book containing educational content Signup and view all the answers

What is one primary advantage of using pulleys?

They change the direction of the force applied. Signup and view all the answers

Pulleys can only be used to lift heavy objects.

False Signup and view all the answers

What are the two main functions of pulleys?

To change the direction and magnitude of the force applied. Signup and view all the answers

A pulley system can reduce the ________ required to lift a load.

effort Signup and view all the answers

Match the pulley functions with their descriptions:

Change direction = Allows pulling down instead of lifting up Reduce effort = Decreases the amount of force needed to lift a load Support weight = Holds the load steady Increase height = Lifts the load to a higher position Signup and view all the answers

Which of the following statements about catalysts is true?

Catalysts do not alter the equilibrium of a reaction. Signup and view all the answers

Endothermic reactions absorb heat from their surroundings.

True Signup and view all the answers

What happens to the solubility of salt when the temperature is increased?

The solubility of salt generally increases. Signup and view all the answers

A solution with a solute mass of 10g in a total solution mass of 150g has a percentage composition of _____%.

6.67 Signup and view all the answers

What is commonly referred to as an exothermic reaction?

Reaction that releases heat Signup and view all the answers

Match the terms with their definitions:

Acid = Substance that donates protons (H+) Base = Substance that accepts protons (H+) Endothermic = Reaction that absorbs energy Exothermic = Reaction that releases energy Signup and view all the answers

What does it mean for a reaction to be thermodynamically favored?

It means the reaction can proceed spontaneously under the given conditions. Signup and view all the answers

A violet color appearing on litmus paper indicates the presence of an acid.

False Signup and view all the answers

Study Notes

The Language of Chemistry

Chemistry uses symbols and numbers to simplify the description of chemical changes.
A chemical reaction transforms reactants into new products, indicating a chemical change.

Chemical Reactions

Burning magnesium produces magnesium oxide, represented via a chemical equation.
Chemical equations have reactants on the left, products on the right, and are separated by an arrow (→).

Reactants and Products

Reactants and products can be expressed in words, symbols, or formulas.
Example of a reaction: Carbon + Oxygen → Carbon Dioxide can also be written as C + O2 → CO2.
A word equation is a simpler term for a chemical equation.

Catalysts

Catalysts accelerate chemical reactions without being consumed or altered.
An example is the decomposition of hydrogen peroxide, which occurs faster with manganese dioxide.

Characteristics of Chemical Reactions

New substances are formed, and chemical properties differ from the original reactants.
Examples include burning wood, combustion of fuels, and rusting of iron.

Chemical Equations

Chemical equations represent reactions using symbols and coefficients indicating the number of molecules involved.

Balancing Chemical Equations

Count atoms of each element on both sides of the equation.
Adjust coefficients to ensure equal numbers of atoms for each element.

Covalent Bonds

Formed when atoms share valence electrons to achieve a stable octet.
Example: In CO2, each oxygen shares electrons with carbon to complete its octet.

Observations of Chemical Reactions

Changes in color, gas evolution, precipitate formation, and heat changes may indicate a reaction.
A color change can signal a chemical change, like copper(II) carbonate turning black when heated.

Evolution of Gases

Gases can evolve during reactions, identifiable by smell (e.g., ammonia’s pungent odor).
Effervescence example: Sodium carbonate reacting with hydrochloric acid produces carbon dioxide.

Precipitate Formation

A solid formed by a reaction in solution can indicate a chemical change, as seen with calcium carbonate formation.

Concentration and Solutions

Solutions are homogeneous mixtures of solute and solvent.
To calculate the percentage composition: (mass of solute / total mass of solution) x 100.

Reaction Rate Influencers

Reaction rate can be affected by:
- Concentration of reactants: Higher concentration typically increases reaction speed.
- Temperature: Increased temperature speeds up reactions.
- Surface area: More exposed area can enhance reaction rate.
- Catalysts: Speed up reactions without being consumed.

Exothermic vs. Endothermic Reactions

Endothermic reactions absorb heat, while exothermic reactions release heat.
Delta H for exothermic reactions is negative.

Acids and Bases

Acids turn blue litmus red; bases turn red litmus blue.
Common property: Both are capable of donating or accepting protons.
Differences: Acids release H+ ions, are sour tasting, and react with metals; bases produce OH- ions, feel slippery, and taste bitter.

Metals

Metals are hard, strong solids with a metallic luster, often excellent conductors of heat and electricity.
They possess high tensile strength, making them suitable for construction and manufacturing.

General Properties of Metals

Common properties include:
- High density and melting points.
- Shiny appearance due to light reflectivity.
- Ability to form alloys.

Summary of Observations

Changes in matter observable in chemical reactions can indicate the formation of new substances and various physical changes.

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Description

Explore the fascinating world of chemical reactions in this quiz. Test your understanding of reactants, products, and the role of catalysts in transforming substances. Learn how to represent these changes through chemical equations and discover the characteristics that define these reactions.