Questions and Answers
What is formed when magnesium burns in air?
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.
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Match the following terms with their definitions:
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Which of the following represents a chemical reaction?
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Hydrogen peroxide decomposes slower in the presence of manganese dioxide.
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Provide one example of a word equation.
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Which of the following indicates a chemical reaction has likely occurred?
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A chemical reaction only involves physical changes in matter.
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What happens to copper(II) carbonate when it is heated?
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A new substance is formed during a __________.
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Match the observations with their implications:
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Which of the following indicates a chemical change?
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A chemical equation is a graphical representation of a chemical reaction.
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What is formed when hydrogen reacts with oxygen?
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A covalent bond is formed when atoms share their ________ electrons.
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Match the following chemical substances with their correct chemical formulas:
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How many covalent bonds can a carbon atom form?
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Combustion of fuel is an example of a physical change.
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What must be done to balance a chemical equation?
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What gas is evolved when ammonium chloride is heated with dry slaked lime?
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Sodium hydroxide is produced when sodium reacts with water.
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What happens when hydrogen is ignited?
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Sodium carbonate reacts with hydrochloric acid to produce sodium chloride, water, and __________.
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Match the following gases with their characteristic smells:
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___ are cell organelles that are involved in protein synthesis.
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Which of the following organelles is responsible for respiration and energy production?
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Humans are made up of prokaryotic cells.
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Match the following cellular structures with their functions:
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What are the functional units of heredity that regulate cellular functions?
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What is formed when ammonia gas reacts with hydrogen chloride gas?
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The reaction of a soluble carbonate with a dilute acid results in the formation of a precipitate.
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What type of change occurs when a spoonful of sugar is dissolved in water?
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When a saturated solution of sodium chloride cools, __________ of sodium chloride can be observed.
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Match the following reactions with their products:
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Which of the following metals is known for its high tensile strength?
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Metals are poor conductors of heat and electricity.
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Name one property that all metals share.
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Iron is commonly used in construction due to its _____ strength.
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Match the following metals with their properties:
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What is likely indicated by the presence of two tables labeled 'Specific Gravity' in the image?
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The presence of an image on the page is clearly discernible.
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What could be the reason for having two tables on a page?
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The two tables labeled Specific Gravity likely contain information about _______.
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Match the following terms with their likely descriptions:
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What is one primary advantage of using pulleys?
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Pulleys can only be used to lift heavy objects.
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What are the two main functions of pulleys?
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A pulley system can reduce the ________ required to lift a load.
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Match the pulley functions with their descriptions:
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Which of the following statements about catalysts is true?
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Endothermic reactions absorb heat from their surroundings.
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What happens to the solubility of salt when the temperature is increased?
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A solution with a solute mass of 10g in a total solution mass of 150g has a percentage composition of _____%.
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What is commonly referred to as an exothermic reaction?
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Match the terms with their definitions:
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What does it mean for a reaction to be thermodynamically favored?
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A violet color appearing on litmus paper indicates the presence of an acid.
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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.