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Questions and Answers
What fundamental change occurs during a chemical reaction?
What fundamental change occurs during a chemical reaction?
- The way atoms and molecules of pure substances are bonded changes. (correct)
- Atoms of one element transform into another element.
- New elements are created from the existing ones.
- The total number of atoms increases.
In a chemical reaction, what distinguishes reactants from products?
In a chemical reaction, what distinguishes reactants from products?
- Reactants are always simpler molecules than products.
- Products are always in a gaseous state, whereas reactants are liquid.
- Reactants are the starting substances, while products are the substances formed after the reaction. (correct)
- Reactants contain more energy than products.
What principle is demonstrated by the fact that the same atoms present in the reactants of a chemical reaction must also be present in the products?
What principle is demonstrated by the fact that the same atoms present in the reactants of a chemical reaction must also be present in the products?
- The Law of Definite Proportions
- The principle of entropy
- The ideal gas law
- The Law of Conservation of Mass (correct)
In a reaction equation, what is the significance of the arrow?
In a reaction equation, what is the significance of the arrow?
Consider the reaction: $NH_3 + HCl \rightarrow NH_4Cl$. What are the reactants in this equation?
Consider the reaction: $NH_3 + HCl \rightarrow NH_4Cl$. What are the reactants in this equation?
Magnesium reacts with hydrochloric acid ($2HCl$) to produce magnesium chloride ($MgCl_2$) and hydrogen gas ($H_2$). In this reaction, what state of matter is magnesium?
Magnesium reacts with hydrochloric acid ($2HCl$) to produce magnesium chloride ($MgCl_2$) and hydrogen gas ($H_2$). In this reaction, what state of matter is magnesium?
Hydrogen ($H_2$) and Oxygen ($O_2$) react to form water ($H_2O$). What best describes the element or compound of water?
Hydrogen ($H_2$) and Oxygen ($O_2$) react to form water ($H_2O$). What best describes the element or compound of water?
When methane ($CH_4$) reacts with oxygen ($O_2$) in a gas stove, what are the products of this chemical reaction?
When methane ($CH_4$) reacts with oxygen ($O_2$) in a gas stove, what are the products of this chemical reaction?
Methane ($CH_4$) reacts with oxygen. How many molecules of oxygen ($O_2$) does each molecule of methane react with?
Methane ($CH_4$) reacts with oxygen. How many molecules of oxygen ($O_2$) does each molecule of methane react with?
Which of the following is NOT a sign of a chemical reaction?
Which of the following is NOT a sign of a chemical reaction?
In a reaction where citric acid and baking soda are mixed, the bottom of the beaker becomes very cold. What does this indicate about the reaction?
In a reaction where citric acid and baking soda are mixed, the bottom of the beaker becomes very cold. What does this indicate about the reaction?
Hydrogen peroxide reacts with potassium iodide and releases energy, resulting in the release of heat. What type of reaction is this?
Hydrogen peroxide reacts with potassium iodide and releases energy, resulting in the release of heat. What type of reaction is this?
When silver nitrate and sodium chloride solutions are mixed, a white solid forms and drops to the bottom of the beaker. What is this solid called?
When silver nitrate and sodium chloride solutions are mixed, a white solid forms and drops to the bottom of the beaker. What is this solid called?
In the reaction $NaOH + HCl \rightarrow NaCl + H_2O$, what type of substance is $NaCl$?
In the reaction $NaOH + HCl \rightarrow NaCl + H_2O$, what type of substance is $NaCl$?
Given the reaction $2Mg + O_2 \rightarrow 2MgO$, what is the element present in the reaction?
Given the reaction $2Mg + O_2 \rightarrow 2MgO$, what is the element present in the reaction?
If silver nitrate ($AgNO_3$) reacts with sodium chloride ($NaCl$) to produce sodium nitrate ($NaNO_3$) and silver chloride ($AgCl$), what type of substance is silver chloride ($AgCl$)?
If silver nitrate ($AgNO_3$) reacts with sodium chloride ($NaCl$) to produce sodium nitrate ($NaNO_3$) and silver chloride ($AgCl$), what type of substance is silver chloride ($AgCl$)?
In the reaction $2H_2O_2 \rightarrow 2H_2O + O_2$, what is hydrogen peroxide ($H_2O_2$)?
In the reaction $2H_2O_2 \rightarrow 2H_2O + O_2$, what is hydrogen peroxide ($H_2O_2$)?
What determines the rate of a chemical reaction?
What determines the rate of a chemical reaction?
According to collision theory, what are the necessary conditions for a chemical reaction to occur?
According to collision theory, what are the necessary conditions for a chemical reaction to occur?
How does temperature influence the rate of a chemical reaction?
How does temperature influence the rate of a chemical reaction?
Why does increasing the concentration of reactants generally speed up a chemical reaction?
Why does increasing the concentration of reactants generally speed up a chemical reaction?
How does increasing the surface area of a solid reactant affect the rate of a chemical reaction?
How does increasing the surface area of a solid reactant affect the rate of a chemical reaction?
What role does a catalyst play in a chemical reaction?
What role does a catalyst play in a chemical reaction?
What is the effect of using boiling water instead of cold water when reacting citric acid with calcium carbonate?
What is the effect of using boiling water instead of cold water when reacting citric acid with calcium carbonate?
Why does powdered calcium carbonate react faster with citric acid than rocks of calcium carbonate?
Why does powdered calcium carbonate react faster with citric acid than rocks of calcium carbonate?
In the 'elephant toothpaste' reaction, hydrogen peroxide breaks down with the help of what catalyst?
In the 'elephant toothpaste' reaction, hydrogen peroxide breaks down with the help of what catalyst?
During a chemical reaction, the observation of a change in color best suggests that:
During a chemical reaction, the observation of a change in color best suggests that:
If a chemical reaction involves the release of gas, what visual evidence would you most likely observe?
If a chemical reaction involves the release of gas, what visual evidence would you most likely observe?
A test tube containing reactants is placed in boiling water, accelerating the reaction. The increase in reaction rate is best attributed to?
A test tube containing reactants is placed in boiling water, accelerating the reaction. The increase in reaction rate is best attributed to?
An experiment is conducted where a solid dissolves faster in a liquid when the solid is crushed into a powder. This observation best demonstrates the effect of:
An experiment is conducted where a solid dissolves faster in a liquid when the solid is crushed into a powder. This observation best demonstrates the effect of:
Which of the following best describes the role of sodium iodide in the 'elephant toothpaste' reaction?
Which of the following best describes the role of sodium iodide in the 'elephant toothpaste' reaction?
Consider a scenario where two clear solutions are mixed in a beaker, and a cloudy, white substance immediately forms. This is what best suggests the:
Consider a scenario where two clear solutions are mixed in a beaker, and a cloudy, white substance immediately forms. This is what best suggests the:
Which statement best describes a catalyst in a chemical reaction?
Which statement best describes a catalyst in a chemical reaction?
Flashcards
What is a chemical reaction?
What is a chemical reaction?
A process that involves the rearrangement of atoms and molecules to form new substances.
What are reactants?
What are reactants?
The substances that are present at the beginning of a chemical reaction.
What are products?
What are products?
The substances that are formed as a result of a chemical reaction.
What is a reaction equation?
What is a reaction equation?
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Fe + S → FeS
Fe + S → FeS
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Mg + 2 HCl → MgCl₂ + H₂
Mg + 2 HCl → MgCl₂ + H₂
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2 H₂ + O₂ → 2 H₂O
2 H₂ + O₂ → 2 H₂O
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CH₄ + 2O₂ → CO₂ + 2 H₂O
CH₄ + 2O₂ → CO₂ + 2 H₂O
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Signs of a chemical reaction?
Signs of a chemical reaction?
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What is the rate of a chemical reaction?
What is the rate of a chemical reaction?
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What is Collision Theory?
What is Collision Theory?
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How does temperature affect reaction rate?
How does temperature affect reaction rate?
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How does concentration affect reaction rate?
How does concentration affect reaction rate?
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How does surface area affect reaction rate?
How does surface area affect reaction rate?
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What is a catalyst?
What is a catalyst?
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Study Notes
Chemical Reactions
- A chemical reaction occurs when the atoms and molecules of pure substances change their bonding.
Chemical Bonds Breaking
- During a chemical reaction, the initial substances break down.
- New substances are made during a chemical reaction.
Reactants and Products
- Reactants are the substances present at the beginning of a reaction.
- Products are the substances that remain after the reaction is complete.
- Atoms are not created or destroyed in a chemical reaction.
- The atoms in the reactants must be present in the products.
Reaction Equations
- Chemists use reaction equations to represent chemical reactions.
- Reaction equations use symbols and formulas to represent elements and compounds.
- An arrow separates the reactants and products.
- A plus sign separates each reactant and product.
- As an example, the reaction of iron with sulphur is: Fe + S -> FeS.
Reaction of Magnesium and Hydrochloric Acid
- Reactants include magnesium, hydrochloric acid and water.
- Products include hydrogen gas, magnesium chloride and water.
- The formula for this reaction is Mg + 2HCI -> MgClâ‚‚ + Hâ‚‚
- In this reaction, Magnesium is an element that is solid.
- In this reaction, hydrochloric acid is a compound that is dissolved in water.
- In this reaction, magnesium chloride is a compound that is dissolved in water.
- In this reaction, hydrogen is an element that is a gas.
Reaction of Hydrogen and Oxygen
- The formula for the reaction of hydrogen and oxygen is 2Hâ‚‚ + Oâ‚‚ -> 2Hâ‚‚O
- Hydrogen and oxygen are elements that are gasses.
- Water is a compound that is a liquid.
Gas Stove
- Natural gas is mostly methane (CHâ‚„).
- Using a gas stove involves a chemical reaction where methane reacts with oxygen (Oâ‚‚) in the air.
- The products of the reaction are carbon dioxide (COâ‚‚) and water vapor (Hâ‚‚O).
- Each methane molecule reacts with two oxygen molecules, represented as CH₄ + 2O₂ → CO₂ + 2H₂O.
Signs of a Chemical Reaction
- Change of temperature can be a sign of a chemical reaction.
- Change of color can be a sign of a chemical reaction.
- Release of light can be a sign of a chemical reaction.
- Release of gas can be a sign of a chemical reaction.
- Formation of a precipitate can be a sign of a chemical reaction.
Change of Temperature
- The reaction between citric acid and baking soda absorbs energy, causing the beaker to become very cold.
- The reaction of hydrogen peroxide with potassium iodide releases energy, and the foam becomes very hot.
Formation of a Precipitate
- Silver nitrate and sodium chloride solutions are colorless.
- When mixed, the solution becomes white.
- White flakes of a white solid fall to the bottom of the beaker.
- Precipitation is when a solid separates out of a solution with flakes falling to the bottom of the beaker.
Station 1
- NaOH + HCl -> NaCl + Hâ‚‚O
- Sodium hydroxide, hydrochloric acid, sodium chloride, and water are all compounds.
Station 2
- 2Mg + O2 -> 2MgO
- Magnesium and Oxygen and elements
- Magnesium oxide is a compound.
Station 4
- NaCl + AgNO₃ -> NaNO₃ + AgCl
- Names: sodium chloride, silver nitrate, sodium nitrate, silver chloride.
- All the reactants and products are compounds.
Station 5
- 2Hâ‚‚Oâ‚‚ -> 2Hâ‚‚O + Oâ‚‚
- Hydrogen peroxide, water, and oxygen are names for each step.
- All the reactants and products are compounds except oxygen which is an element.
Rate of a Chemical Reaction
- The rate of a chemical reaction refers to the speed at which the reaction happens.
- It is determined by the speed at which reactants are used and products are formed.
Temperature
- Temperature measures the average energy of moving particles.
- Higher temperature means particles have more energy and move faster.
- This increases the chance of collision leading to a reaction.
- Faster movement means more collisions which will lead to a faster reaction.
- More energy means a better chance of starting a reaction.
- Citric acid reacts with calcium carbonate faster in boiling water than in cold water.
Concentration
- Concentration is the amount of a substance in a certain space.
- For solutions, concentration is the amount of solute dissolved in a certain amount of solution.
- If 1 mL of citric acid is dissolved in 10 mL of water, the concentration is 1 mL/10 mL, or 10%.
- Increasing the concentration means there are more particles in the same space.
- More particles result in more collisions, which leads to a faster reaction.
- Concentrated citric acid reacts with calcium carbonate faster than diluted citric acid.
Surface Area
- Surface area refers to the area on the surface (outside) of a solid.
- Particles on the surface are immediately available to react if the solid is placed in a liquid.
- Increasing the surface area means more particles are exposed to the reactants.
- More particles lead to more collisions, which results in a faster reaction.
- Powdered calcium carbonate reacts faster with citric acid than rocks of calcium carbonate.
Catalyst
- Is a substance that helps a chemical reaction occur without being consumed in the reaction itself.
- It reduces the amount of energy required by bringing particles together in the correct orientation.
- Less energy required leads to a better chance of starting a reaction.
- Correct orientation leads to a better chance of starting a reaction.
- Enzymes are catalysts in biology.
- The reaction for elephant toothpaste is 2 H₂O₂ + NaI → 2 H₂O + O₂ + NaI, where sodium iodide is the catalyst.
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