Chemical Reactions Flashcards
What is a physical change?
A physical change is a change that does not produce any new chemical substances and is often easy to reverse.
What is a chemical change?
A chemical change is a change where new chemical substances are formed, often with very different properties from the reactants.
What indicates a chemical change has occurred?
Signs of a chemical change include colour changes, temperature changes, and effervescence (fizzing).
What is effervescence?
Effervescence is the rapid escape of gas from a liquid in which it is dissolved, causing fizzing.
What colour change occurs in the metal displacement reaction of silver nitrate and copper?
The solid changes from orange-brown to silver, and the solution changes from colourless to blue.
State one example of a physical change.
Melting
State the two types of reactions that cause a change in temperature.
Exothermic & Endothermic
What has a greater surface area, magnesium ribbon or magnesium powder?
Magnesium powder has a greater surface area.
What four factors affect the rate of a chemical reaction?
- Concentration
- Area
- Temperature
- Catalyst
A steep gradient on a rate of reaction graph indicates ……..
A steep gradient on a rate of reaction graph indicates a fast rate of reaction.
Will increasing or decreasing the temperature increase the rate of reaction?
Increasing the temperature will increase the rate of reaction.
Define the term collision theory.
A theory that explains how rates of reaction depend on the frequency and energy of collisions between reactant particles.
State the relationship between the number of collisions and the number of particles
The number of collisions is proportional to the number of particles present.
Define the term successful collision
A successful collision is a collision between reactant particles that leads to the formation of product molecules.
Define activation energy
Activation energy is the minimum energy that reacting particles must have for a reaction to occur.
How does the increasing the kinetic energy of the particles affect the number of successful collisions?
Greater kinetic energy means a greater proportion of collisions will have an energy that exceeds the activation energy.
What is a catalyst?
A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the reaction.
How is the rate of reaction measured?
Product formed or Reactant Used / Time
Give three techniques used in a lab that are used to measure the rate of a reaction.
measuring mass loss on a balance.
measuring the volume of a gas produced.
measuring a reaction where there is a colour change at the end of the reaction.
Define the term reversible reaction.
A reversible reaction is a reaction that can occur in both directions
How are reversible reactions represented in chemical equations?
⇌
When ammonium chloride is heated, what are the products of the reaction?
When ammonium chloride is heated, ammonia and hydrogen chloride are formed.
State what is observed when hydrated copper sulfate is heated.
When hydrated copper sulfate is heated the colour change is blue to white and colourless liquid (water) collects at the top of the test tube.
What is an anhydrous salt?
Anhydrous salts are those that have lost their water of crystallisation.
What is the effect of decreasing the concentration of a product?
Decreasing the concentration of a product shifts the equilibrium to the left, favouring the reactants.
If the concentration of a reactant decreases, how does the equilibrium shift?
Equilibrium shifts to the left to reduce the effect of a decrease in reactant (or an increase in the concentration of product).
Define the term dynamic equilibrium.
Dynamic equilibrium is where the rate of the forward reaction equals the rate of the reverse reaction, and the concentrations of reactants and products remain constant.
Define the term closed system.
A closed system is a system where none of the reactants or products can enter or leave the reaction vessel.
Define the term open system
An open system is a system where the reactants or products can both enter or leave the reaction vessel.
What is the Haber Process?
The Haber Process is the industrial process for manufacturing ammonia from nitrogen and hydrogen gases.
What catalyst is used in the Haber Process?
The catalyst used in the Haber Process is iron.
What is the main product of the Contact process?
The main product of the Contact process is sulfuric acid.
What is the catalyst used in the main stage of the Contact process?
The catalyst used in the main stage of the Contact process is vanadium(V) oxide, V₂O₅.
Define oxidation in terms of oxygen.
Oxidation is any reaction in which a substance gains oxygen.
Define reduction in terms of oxygen.
Reduction is a reaction in which a substance loses oxygen.
Define the term redox reaction.
A redox reaction is when oxidation and reduction take place simultaneously.
What does the Roman numeral in iron(III) oxide tell us?
The roman numeral tells us the oxidation number of the iron.
What is the charge of copper in copper(II) chloride?
The copper has a 2+ charge in copper(II) chloride.
Define oxidation in terms of electrons.
Oxidation is the loss of electrons.
Define reduction in terms of electrons.
Reduction is the gain of electrons.
Define the term oxidising agent in terms of electrons
In terms of electrons, an oxidising agent accepts electrons.
An oxidising agent is reduced.
