Chemical Reactions
What is a sign that a chemical reaction has occurred?
Gas, light, temp, new substance, color change
What is Neutralisation
Neutralisation occurs when an acid and a base react to form water and a salt. This works because hydrogen ions (H⁺) from the acid combine with hydroxide ions (OH⁻) from the base to form water.
What is an acid
An acid is a substance that reacts with a base to produce salt and water.
OR
Acids release their hydrogen ions (H+) in water and their strength depends on how completely they release hydrogen ions (H⁺) in water
Is this equation balanced?
Fe2O3 + Al → Fe + Al2O3
No --> Fe2O3 + 2Al → 2Fe + Al2O3
Exothermic reactions are where energy in the form of heat is;
released
Definition of a chemical reaction?
Reaction where a new substance is formed.
What is this compound?
H20
water
Compounds in a reaction on the left side of the arrow are the ________, on the right side of the arrow they are called the ________.
Reactants, products.
Basic principle for making sure that chemical equations and number of atoms are balanced?
Law of Conservation of Matter
Are electrons lost or gained during Oxidation
Electrons are lost
What is a Base
Bases neutralise acids and usually produce hydroxide ions (OH⁻) in solution
What is the formula for dihydrogen monoxide?
H2O
The subscripts tell you what about chemical equations?
The number of atoms of each atom or ion in a formula
The numbers that we can add into equations at the start of chemical formulas are called?
Coefficients
In both endo and exothermic reactions, energy is taken in / released in the form of;
What is the pH scale
The pH scales measures how acidic or basic a substance is. It ranges from 0 to 14.
Which element is found in NaOH?
nitrogen , nobelium, sodium, hydroxide
sodium - Na
Symbol equation for the following worded equation?
carbon monoxide + water -> carbon dioxide + hydrogen
CO + H2O -> CO2 + H
How many potassium, oxygen and hydrogen atoms, respectively, are there on the product side.
2 K (s) + 2 H2O (l) → 2 KOH (aq) + H2 (g)
2, 2, 4
During an exothermic reaction the temperature of the surroundings;
Increases
What is wrong with this equation?
3LiCl + Br2 -> LiBr + Cl2
It is unbalanced -->
2LiCl + Br2 -> 2LiBr + Cl2
A symbol stands for an element,
A formula stands for a _________
compound
What symbol means 'yields' or 'produces'?
the arrow -->
Balance this equation?
N2 + H2 -> NH3
N2 + 3H2 -> 2NH3
Energy is released when the reaction breaks --- and energy is absorbed when the reaction makes new ---.
1. Break bonds
2. Make new bonds