Chapter 4 Test Flashcards
Chemical Reaction
The changes or transformations of various kinds of matter into other substances with different compositions, structures and properties described using chemical equations
Evidence/observations of a chemical reaction
Change in temperature Evolution of a gas Formation of a Precipitate Change in colour Formation of an odour
3 Laws a Chemical Reaction Must Follow
- Conservation of Mass
- Conservation of Charge
- Conservation of Energy
Conservation of Mass
The total mass of the reactants equals the total mass of the products
balance equation
Conservation of Charge
Since the total # of electrons and protons after a chemical reaction is the same as before the reaction, the # of positive and negative charges remains constant
Charge of reactant = charge of product
Conservation of Energy
The total amount of energy after a chemical reaction equals the total amount of energy before the reaction
What does a chemical reaction require?
What is the rate of reaction determined by?
A chemical reaction requires a collision between reactant particles
The rate of a reaction is determined by measuring the amount of products formed
5 Factors Affecting the Rate of a Chemical Reaction
- Temperature
- Catalysts/Enzymes
- Concentration and Surface Area
- Pressure
- Reversiblity
Temperature
An increase causes an increase in in the rate of the chemical reaction
An increase in temperature results in an increase in the kinetic energy (movement of the particles) of the reactants; this causes the reactants to collide faster, harder and more often, increasing the chances to form bonds
Catalysts/ Enzymes
A chemical which speeds up a reaction but is itself unaffected
A catalyst lowers the initial energy “kick”/ activation energy required to start a reaction
Concentration and Surface Area
An increase in the concentration of reactants and an increase in the surface area increases the rate of reaction.
Pressure
It has no effect on the volume of a solid or liquid, therefore, no effect on the rate of the reaction
→ an increase in the pressure exerted on a gas will decrease the volume which in turn increases the concentration, therefore, an increase in the rate
Reversibility
Does not influence the rate of a chemical reaction, however, not all reactants are converted to products
Chemical equation
A shorthand description of a chemical change using symbols and formulas to indicate the substances involved in the change
Reactant
A substance that undergoes a chemical reaction
Product
A substance that is formed in a chemical reaction
Endothermic
Energy is absorbed (feels cold) +△H
Exothermic
Energy is given off (feels hot) -△H
Precipitate
An insoluble solid that forms when 2 liquids are mixed
Synthesis Reaction
A + B → AB
Atoms and molecules join together directly to produce larger molecules
Combustion and corrosion are synthesis reactions
Decomposition
AB → A + B
The exact opposite of synthesis reactions
Special Synthesis and Decomposition Reactions: metal oxide (basic oxide) + water
Metal oxide (basic oxide) + water→base
_____ hydroxide OH
Ex: MgO + H2O → Mg(OH)2
Mg(OH)2 →MgO + H2O
Special Synthesis and Decomposition Reactions:
Non-metal oxide(acidic oxide)+ water
Non-metal oxide(acidic oxide)+ water→ acid
______ic acid H oxyacid can be used too
Ex: CO2 + H2O → H2CO3(aq)
H2CO3(aq) → CO2(g) + H2O
Special Synthesis and Decomposition Reactions:
Metal oxide + Non-metal oxide
Metal oxide + non-metal oxide → metal oxyanion
EX: MgO +CO2 →MgCO3
MgCO3 → MgO + CO2
Complete Combustion:
Sufficient supply of oxygen
CH(g) + O2(g) → CO2(g) + H20(g) + energy (exothermic)
Hydrocarbon + oxygen→ carbon dioxide + water vapour + energy
Incomplete Combustion
Insufficient supply of oxygen
CH(g) + O2(g)→ CO2(g) + H2O(g) + CO(g) + C(s) + energy
Hydrocarbon + oxygen → carbon dioxide + water vapour + carbon monoxide + carbon + energy
Danger of Incomplete Combustion
Carbon monoxide gas is dangerous because of its physical properties. It is a gas, odourless and non-combustible. It has the same configuration as oxygen so it competes with oxygen to bind to the hemoglobin sites in the RBC’s. But unlike oxygen, the binding to hemoglobinis permanent. The somatic cells will eventually starve of oxygen and die. High CO in the body is lethal
Symptoms of CO poisoning
Dizziness Headache Nausea Vomiting Shortness of breath Loss of consciousness
Visible signs of incomplete combustion
Yellow flame instead of blue flame
Formation of soot
Soot
Carbon monoxide + Carbon
To determine a type of gas during gas test
OXYGEN: use a glowing splint and it will burst into flames
CARBON DIOXIDE: a burning splint will have its flame extinguish OR use limewater and the water will turn from clear→ cloudy
HYDROGEN: you will hear a ‘pop’ from a burning splint
any time carbonic acid or ammonium hydroxide is formed as a product, it decomposes further
Carbonic acid: H2CO3 (aq)
→ H2O (l) + CO2 (g)
Ammonium hydroxide:NH4OH (aq)
→H2O (l) + NH3 (g)
NO REACTION: single displacement
If the 1st metal is less reactive than the 2nd metal
Use activity series chart
NO REACTION: double displacement
If the 1st metal is less reactive than the 2nd metal
If neither soluble ionic compounds precipitates out
Group 17: if halogen (standalone) is higher than the halogen in the compound, a reaction will take place
Yes
