Y10 Chemistry Trilogy: Organic Chemistry & Equilibrium

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Questions and Answers

Which of the following statements best describes the formation of crude oil?

Crude oil is formed from the rapid decomposition of volcanic rock under high pressure.
Crude oil is the result of the slow decomposition of marine organisms under high pressure and temperature over millions of years. (correct)
Crude oil is created from the chemical weathering of sedimentary rocks.
Crude oil is synthesized from atmospheric gases through photochemical reactions.

A hydrocarbon is a compound consisting exclusively of carbon and hydrogen atoms.

True (A)

Provide the chemical formula for butane and draw its structural formula.

Chemical formula: $C_4H_{10}$. Structural formula: A four-carbon chain with each carbon atom bonded to enough hydrogen atoms to satisfy its tetravalency.

In fractional distillation, substances are separated based on their different ______ points.

boiling Signup and view all the answers

Match each hydrocarbon trend in crude oil with its correct description:

Boiling Point = Increases with increasing molecular size due to stronger van der Waals forces. Viscosity = Increases with increasing molecular size due to greater intermolecular attractions. Flammability = Decreases with increasing molecular size due to higher energy needed for vaporization. Signup and view all the answers

When a hydrocarbon undergoes complete combustion, what are the primary products formed?

Carbon dioxide and water (C) Signup and view all the answers

Cracking is a process that converts smaller hydrocarbons into larger, less useful molecules.

False (B) Signup and view all the answers

Briefly describe the key differences in the conditions used for steam cracking and catalytic cracking.

Steam cracking uses high temperatures and steam, while catalytic cracking uses lower temperatures and catalysts. Signup and view all the answers

To test for the presence of a double bond in an alkene, you would typically use water, and a positive result is indicated by the of the solution.

bromine, discoloration Signup and view all the answers

In a chemical reaction at equilibrium, what does it mean when the forward and reverse reaction rates are equal?

The net change in concentrations of reactants and products is zero. (A) Signup and view all the answers

Adding a catalyst shifts the equilibrium position to favor the products.

False (B) Signup and view all the answers

State Le Chatelier's principle in your own words.

If a change of condition is applied to a system in equilibrium, the system will shift in a direction that relieves the stress. Signup and view all the answers

According to Le Chatelier's principle, increasing the temperature in an exothermic reaction will shift the equilibrium towards the ______ side.

reactant Signup and view all the answers

Match the change in reaction condition with its effect on the equilibrium of a reversible reaction:

Increase in Reactant Concentration = Shifts equilibrium towards products. Increase in Product Concentration = Shifts equilibrium towards reactants. Increase in Pressure (for gaseous reactions) = Shifts equilibrium towards the side with fewer moles of gas. Signup and view all the answers

For a reaction at equilibrium that produces fewer moles of gas on the product side, how will an increase in pressure affect the equilibrium position?

Shift towards the products (C) Signup and view all the answers

The rate of a chemical reaction is constant and cannot be altered by external factors.

False (B) Signup and view all the answers

Explain how to calculate the rate of a reaction from data or the gradient of a graph.

The rate of reaction can be calculated by determining the change in concentration of a reactant or product over time. This is often found by calculating the slope (gradient) of a concentration vs. time graph. Signup and view all the answers

According to collision theory, for a reaction to occur, reactant particles must collide with sufficient and proper .

energy, orientation Signup and view all the answers

Match each factor with its effect on the rate of reaction:

Increased Concentration of Reactants = Increases the rate of reaction by increasing frequency of collisions. Increased Temperature = Increases the rate of reaction by increasing the kinetic energy of particles and collision frequency. Increased Surface Area of Solid Reactants = Increases the rate of reaction by providing more area for collisions. Presence of a Catalyst = Increases the rate of reaction by lowering the activation energy. Signup and view all the answers

How does a catalyst increase the rate of a reaction?

By providing an alternate reaction pathway with a lower activation energy (A) Signup and view all the answers

The Earth's atmosphere has remained constant in composition throughout its entire history.

False (B) Signup and view all the answers

Briefly explain how the Earth's oceans were formed.

Oceans formed from water vapor released by volcanic activity, which condensed as the Earth cooled over millions of years. Signup and view all the answers

The Great Oxidation Event led to a significant in atmospheric carbon dioxide levels and an increase in atmospheric levels.

decrease, oxygen Signup and view all the answers

Match each process with its effect on carbon dioxide levels in the early Earth's atmosphere:

Photosynthesis = Decreased carbon dioxide levels by converting it into organic compounds and oxygen. Formation of Sedimentary Rocks = Decreased carbon dioxide levels through the long-term storage of carbon in minerals like limestone. Ocean Absorption = Decreased carbon dioxide levels by dissolving CO2 in seawater. Signup and view all the answers

What was the primary mechanism for the increase in oxygen levels in the Earth's atmosphere?

Photosynthesis by early cyanobacteria (B) Signup and view all the answers

Nitrogen levels in the atmosphere have decreased significantly over geological time.

False (B) Signup and view all the answers

Explain how levels of nitrogen increased in the Earth's atmosphere over time.

Nitrogen increased due to volcanic outgassing and biological processes such as denitrification. Its inert nature prevents it from being easily removed from the atmosphere. Signup and view all the answers

Which of the following is NOT a direct factor affecting chemical equilibrium?

Catalyst (A) Signup and view all the answers

According to Le Chatelier's principle, adding an inert gas at constant volume will shift the equilibrium position.

False (B) Signup and view all the answers

The rate of reaction typically with an increase in temperature because particles have more energy, leading to more effective collisions.

increases, kinetic Signup and view all the answers

Match the following descriptions with the type of cracking they describe

Steam cracking = Uses high temperatures and steam to break down hydrocarbons Catalytic cracking = Uses lower temperatures and a catalyst to break down hydrocarbons Signup and view all the answers

What best describes chemical equilibrium?

The state where the rates of the forward and reverse reactions are equal (C) Signup and view all the answers

An increase in pressure always favors the side of the equilibrium with more gas molecules.

False (B) Signup and view all the answers

What is the effect of a decrease in temperature on an endothermic reaction at equilibrium?

Decreasing the temperature will shift the equilibrium towards the reactants. Signup and view all the answers

In the early Earth's atmosphere, high levels of volcanic activity contributed primarily to increased concentrations of water and ______.

carbon dioxide Signup and view all the answers

Match the term with its description:

Cracking = A process to break big hydrocarbons into smaller ones Hydrocarbon = A compound consisting only of hydrogen and carbons Alkene = A hydrocarbon with double carbon-carbon bonds Signup and view all the answers

Photosynthesis had what effect on the atmosphere

Increased the proportion of oxygen over time (B) Signup and view all the answers

A hydrocarbon is made of what two elements?

Carbon, Hydrogen (C) Signup and view all the answers

Why did the amount of Nitrogen increase in the atmosphere?

Due to it's inertness, it built up over time (D) Signup and view all the answers

Signup and view all the answers

Flashcards

Formation of crude oil

Crude oil is formed from the remains of plants and animals, mainly plankton, that died millions of years ago and were buried under layers of sediment. Heat and pressure over millions of years transformed them into crude oil.

Hydrocarbon

A hydrocarbon is a compound made of hydrogen and carbon atoms only.

First four alkanes formulas

Methane (CH4), Ethane (C2H6), Propane (C3H8), Butane (C4H10).

Fractional distillation of crude oil

Fractional distillation separates crude oil into fractions based on boiling points. Products include: refinery gas, gasoline, kerosene, diesel, fuel oil, and bitumen.